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2017MNRAS.464..946S

Assisted inspirals of stellar mass black holes embedded in AGN discs: solving the `final au problem'

2017-01-01

['gravitational waves', 'galaxies nuclei', 'galaxies quasars', 'galaxies quasars', '-', '-', '-', '-']

[]

We explore the evolution of stellar mass black hole binaries (BHBs) which are formed in the self-gravitating discs of active galactic nuclei (AGN). Hardening due to three-body scattering and gaseous drag are effective mechanisms that reduce the semimajor axis of a BHB to radii where gravitational waves take over, on time-scales shorter than the typical lifetime of the AGN disc. Taking observationally motivated assumptions for the rate of star formation in AGN discs, we find a rate of disc-induced BHB mergers (R ∼ 3 yr^{-1} Gpc^{-3}, but with large uncertainties) that is comparable with existing estimates of the field rate of BHB mergers, and the approximate BHB merger rate implied by the recent Advanced LIGO detection of GW150914. BHBs formed thorough this channel will frequently be associated with luminous AGN, which are relatively rare within the sky error regions of future gravitational wave detector arrays. This channel could also possess a (potentially transient) electromagnetic counterpart due to super-Eddington accretion on to the stellar mass black hole following the merger.

[]

https://arxiv.org/pdf/1602.04226.pdf

1997PhRvL..78.3606B

A Simple Construction of Initial Data for Multiple Black Holes

1997-01-01

['-']

[]

We consider the initial data problem for several black holes in vacuum with arbitrary momenta and spins on a three space with punctures. We compactify the internal asymptotically flat regions to obtain a computational domain without inner boundaries. When treated numerically, this leads to a significant simplification over the conventional approach which is based on throats and isometry conditions. In this new setting it is possible to obtain existence and uniqueness of solutions to the Hamiltonian constraint.

[]

https://arxiv.org/pdf/gr-qc/9703066.pdf

2012MNRAS.426.3241N

GRMHD simulations of magnetized advection-dominated accretion on a non-spinning black hole: role of outflows

2012-01-01

['accretion', 'accretion disks', 'black hole physics', 'atmosphere', 'methods numerical', 'stars binaries close', 'galaxies jets', '-']

[]

We present results from two long-duration general relativistic magneto-hydrodynamic (GRMHD) simulations of advection-dominated accretion around a non-spinning black hole. The first simulation was designed to avoid significant accumulation of magnetic flux around the black hole. This simulation was run for a time of 200 000 GM/c<SUP>3</SUP> and achieved inflow equilibrium out to a radius ∼90 GM/c<SUP>2</SUP>. Even at this relatively large radius, the mass outflow rate M⊙ out is found to be only 60 per cent of the net mass inflow rate M⊙ BH into the black hole. The second simulation was designed to achieve substantial magnetic flux accumulation around the black hole in a magnetically arrested disc. This simulation was run for a shorter time of 100 000 GM/c<SUP>3</SUP>. Nevertheless, because the mean radial velocity was several times larger than in the first simulation, it reached inflow equilibrium out to a radius ∼170 GM/c<SUP>2</SUP>. Here, M⊙ out becomes equal to M⊙ BH at r ∼ 160 GM/c<SUP>2</SUP>. Since the mass outflow rates in the two simulations do not show robust convergence with time, it is likely that the true outflow rates are lower than our estimates. The effect of black hole spin on mass outflow remains to be explored. Neither simulation shows strong evidence for convection, though a complete analysis including the effect of magnetic fields is left for the future.

[]

https://arxiv.org/pdf/1206.1213.pdf

2015Sci...349.1522S

Gravitational waves from binary supermassive black holes missing in pulsar observations

2015-01-01

['-', '-', '-', '-', '-']

[]

Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems would modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrained the characteristic amplitude of this background, A<SUB>c,yr</SUB>, to be &lt;1.0 × 10<SUP>-15</SUP> with 95% confidence. This limit excludes predicted ranges for A<SUB>c,yr</SUB> from current models with 91 to 99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments and that higher-cadence and shorter-wavelength observations would be more sensitive to gravitational waves.

[]

https://arxiv.org/pdf/1509.07320.pdf

2008MNRAS.390..192S

The stochastic gravitational-wave background from massive black hole binary systems: implications for observations with Pulsar Timing Arrays

2008-01-01

['black hole physics', 'gravitational waves', '-', 'cosmology theory', 'astrophysics', '-']

[]

Massive black hole binary systems, with masses in the range ~10<SUP>4</SUP>-10<SUP>10</SUP>M<SUB>solar</SUB>, are among the primary sources of gravitational waves in the frequency window ~10<SUP>-9</SUP>-0.1Hz. Pulsar Timing Arrays (PTAs) and the Laser Interferometer Space Antenna (LISA) are the observational means by which we will be able to observe gravitational radiation from these systems. We carry out a systematic study of the generation of the stochastic gravitational-wave background from the cosmic population of massive black hole binaries. We consider a wide variety of assembly scenarios and we estimate the range of signal strength in the frequency band accessible to PTAs. We show that regardless of the specific model of massive black hole binaries formation and evolution, the characteristic amplitude h<SUB>c</SUB> of the gravitational-wave stochastic background at 10<SUP>-8</SUP> Hz varies by less than a factor of 2. However, taking into account the uncertainties surrounding the actual key model parameters, the amplitude lies in the interval h<SUB>c</SUB>(f = 10<SUP>-8</SUP>Hz) ~ 5 × 10<SUP>-16</SUP>-8 × 10<SUP>-15</SUP>. The most optimistic predictions place the signal level at a factor of ~3 below the current sensitivity of PTAs, but within the detection range of the complete Parkes PTA for a wide variety of models, and of the future Square-Kilometer Array PTA for all the models considered here. We also show that at frequencies &gt;~10<SUP>-8</SUP> Hz, the frequency dependency of the generated background follows a power law significantly steeper than h<SUB>c</SUB> ~ f<SUP>-2/3</SUP>, which has been considered so far; the value of the spectral index depends on the actual assembly scenario and provides therefore an additional opportunity to extract astrophysical information about the cosmic population of massive black holes. Finally, we show that LISA observations of individual resolvable massive black hole binaries are complementary and orthogonal to PTA observations of a stochastic background from the whole population in the Universe. In fact, the detection of gravitational radiation in both frequency windows will enable us to fully characterize the cosmic history of massive black holes.

[]

https://arxiv.org/pdf/0804.4476.pdf

2012LRR....15....7C

Stationary Black Holes: Uniqueness and Beyond

2012-01-01

['-', '-', 'black hole physics', '-', '-', '-', '-', '-', '-']

[]

The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.

[]

https://arxiv.org/pdf/1205.6112.pdf

2013EPJC...73.2487T

Black hole thermodynamical entropy

2013-01-01

['-']

[]

As early as 1902, Gibbs pointed out that systems whose partition function diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs (BG) theory. Consistently, since the pioneering Bekenstein-Hawking results, physically meaningful evidence (e.g., the holographic principle) has accumulated that the BG entropy S <SUB>BG</SUB> of a (3+1) black hole is proportional to its area L <SUP>2</SUP> ( L being a characteristic linear length), and not to its volume L <SUP>3</SUP>. Similarly it exists the area law, so named because, for a wide class of strongly quantum-entangled d-dimensional systems, S <SUB>BG</SUB> is proportional to ln L if d=1, and to L <SUP> d-1</SUP> if d&gt;1, instead of being proportional to L <SUP> d </SUP> ( d≥1). These results violate the extensivity of the thermodynamical entropy of a d-dimensional system. This thermodynamical inconsistency disappears if we realize that the thermodynamical entropy of such nonstandard systems is not to be identified with the BG additive entropy but with appropriately generalized nonadditive entropies. Indeed, the celebrated usefulness of the BG entropy is founded on hypothesis such as relatively weak probabilistic correlations (and their connections to ergodicity, which by no means can be assumed as a general rule of nature). Here we introduce a generalized entropy which, for the Schwarzschild black hole and the area law, can solve the thermodynamic puzzle.

[]

https://arxiv.org/pdf/1202.2154.pdf

1999PhRvL..82.2828C

Black Hole Entropy from Conformal Field Theory in Any Dimension

1999-01-01

['-', '-']

[]

Restricted to a black hole horizon, the ``gauge'' algebra of surface deformations in general relativity contains a Virasoro subalgebra with a calculable central charge. The fields in any quantum theory of gravity must transform accordingly, i.e., they must admit a conformal field theory description. Applying Cardy's formula for the asymptotic density of states, I use this result to derive the Bekenstein-Hawking entropy. This method is universal-it holds for any black hole, and requires no details of quantum gravity-but it is also explicitly statistical mechanical, based on counting microscopic states.

[]

https://arxiv.org/pdf/hep-th/9812013.pdf

1998ApJ...492..554N

Advection-dominated accretion model of Sagittarius A<SUP>*</SUP>: evidence for a black hole at the Galactic center.

1998-01-01

['galaxies nuclei', 'black hole physics', 'accretion disks', 'galaxies nuclei', 'accretion', 'accretion disks', 'black hole physics', 'galaxy center', 'radiation', 'astrophysics']

[]

Sagittarius A<SUP>*</SUP>, which is located at the Galactic center, is a puzzling source. It has a mass of M = (2.5 +/- 0.4) × 10<SUP>6</SUP> M<SUB>⊙</SUB>, which makes it an excellent black hole candidate. Observations of stellar winds and other gas flows in its vicinity suggest a mass accretion rate of Ṁ&gt;~few×10<SUP>-6</SUP> M<SUB>⊙</SUB> yr<SUP>-1</SUP>. However, such an accretion rate would imply a luminosity greater than 10<SUP>40</SUP> ergs<SUP>-1</SUP> if the radiative efficiency is the usual 10%, whereas observations indicate a bolometric luminosity less than 10<SUP>37</SUP> ergs<SUP>-1</SUP>. The spectrum of Sgr A<SUP>*</SUP> is unusual, with emission extending over many decades of wavelength. We present a model of Sgr A<SUP>*</SUP> that is based on a two-temperature optically thin advection-dominated accretion flow. The model is consistent with the estimated M and Ṁ and fits the observed fluxes in the centimeter/millimeter and X-ray bands, as well as upper limits in the submillimeter and infrared bands; the fit is less good in the radio spectrum below 86 GHz and in γ-rays above 100 MeV. The very low luminosity of Sgr A<SUP>*</SUP> is explained naturally in the model by means of advection. Most of the viscously dissipated energy is advected into the central mass by the accreting gas, and therefore the radiative efficiency is extremely low, ~5 × 10<SUP>-6</SUP>. A critical element of the model is the presence of an event horizon at the center that swallows the advected energy. The success of the model could thus be viewed as confirmation that Sgr A<SUP>*</SUP> is a black hole.

[]

https://arxiv.org/pdf/astro-ph/9706112.pdf

1995PhRvD..51.4302H

Entropy, area, and black hole pairs

1995-01-01

['-', '-', '-', '-', '-', '-', '-']

[]

We clarify the relation between gravitational entropy and the area of horizons. We first show that the entropy of an extreme Reissner-Nordström black hole is zero, despite the fact that its horizon has nonzero area. Next, we consider the pair creation of extremal and nonextremal black holes. It is shown that the action which governs the rate of this pair creation is directly related to the area of the acceleration horizon and (in the nonextremal case) the area of the black hole event horizon. This provides a simple explanation of the result that the rate of pair creation of nonextreme black holes is enhanced by precisely the black hole entropy. Finally, we discuss black hole annihilation, and argue that Planck scale remnants are not sufficient to preserve unitarity in quantum gravity.

[]

https://arxiv.org/pdf/gr-qc/9409013.pdf

2016PhRvD..93l2003A

GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

2016-01-01

['-', '-', '-']

[]

On September 14, 2015, at 09∶50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015 GW150914 was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ .

[]

https://arxiv.org/pdf/1602.03839.pdf

2004IJMPA..19.4899K

Black Holes in Theories with Large Extra Dimensions:

2004-01-01

['black hole physics', '-', '-', '-', 'astrophysics', '-', '-']

[]

We start by reviewing the existing literature on the creation of black holes during high-energy particle collisions, both in the absence and in the presence of extra, compact, spacelike dimensions. Then, we discuss in detail the properties of the produced higher-dimensional black holes, namely the horizon radius, temperature and life-time, as well as the physics that governs the evaporation of these objects, through the emission of Hawking radiation. We first study the emission of visible Hawking radiation on the brane: we derive a master equation for the propagation of fields with arbitrary spin in the induced-on-the-brane black hole background, and we review all existing results in the literature for the emission of scalars, fermions and gauge bosons during the spin-down and Schwarzschild phases of the life of the black hole. Both analytical and numerical results for the graybody factors and radiation spectra are reviewed and exact results for the number and type of fields emitted on the brane as a function of the dimensionality of space-time are discussed. We finally study the emission of Hawking radiation in the bulk: graybody factors and radiation spectra are presented for the emission of scalar modes, and the ratio of the missing energy over the visible one is calculated for different values of the number of extra dimensions.

[]

https://arxiv.org/pdf/hep-ph/0402168.pdf

1995PhLB..360....7B

Spectroscopy of the quantum black hole

1995-01-01

['-', '-', '-']

[]

We develop the idea that, in quantum gravity where the horizon fluctuates, a black hole should have a discrete mass spectrum with concomitant line emission. Simple arguments fix the spacing of the lines, which should be broad but unblended. Assuming uniformity of the matrix elements for quantum transitions between near levels, we work out the probabilities for the emission of a specified series of quanta andtthe intensities of the spectral lines. The thermal character of the radiation is entirely due to the degeneracy of the levels, the same degeneracy that becomes manifest as black hole entropy. One prediction is that there should be no lines with wavelength of the order of the black hole size or larger. This makes it possible to test quantum gravity with black holes well above Planck scale.

[]

https://arxiv.org/pdf/gr-qc/9505012.pdf

1997ApJ...489..579M

The Supermassive Black Hole of M87 and the Kinematics of Its Associated Gaseous Disk

1997-01-01

['black hole physics', 'galaxies', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'astrophysics']

[]

We have obtained long-slit observations of the circumnuclear region of M87 at three different locations, with a spatial sampling of 0.028" using the Faint Object Camera f/48 spectrograph on board HST. These data allow us to determine the rotation curve of the inner ~1" of the ionized gas disk in [O II] λ3727 to a distance as close as 0.07" (~=5 pc) to the dynamic center, thereby significantly improving on both the spatial resolution and coverage of previous FOS observations. We have modeled the kinematics of the gas under the assumption of the existence of both a central black hole and an extended central mass distribution, taking into account the effects of the instrumental PSF, the intrinsic luminosity distribution of the line, and the finite size of the slit. We find that the central mass must be concentrated within a sphere whose maximum radius is 0.05" (~=3.5 pc) and show that both the observed rotation curve and line profiles are consistent with a thin disk in Keplerian motion. We conclude that the most likely explanation for the observed motions is the presence of a supermassive black hole and derive a value of M<SUB>BH</SUB> = (3.2 +/- 0.9) × 10<SUP>9</SUP> M<SUB>⊙</SUB> for its mass. <P />Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555 and by STScI grant GO-3594.01-91A.

[]

https://arxiv.org/pdf/astro-ph/9706252.pdf

2017PhRvD..95d3534A

Cosmic microwave background limits on accreting primordial black holes

2017-01-01

['-', '-']

[]

Interest in the idea that primordial black holes (PBHs) might comprise some or all of the dark matter has recently been rekindled following LIGO's first direct detection of a binary-black-hole merger. Here we revisit the effect of accreting PBHs on the cosmic microwave background (CMB) frequency spectrum and the angular temperature and polarization power spectra. We compute the accretion rate and luminosity of PBHs, accounting for their suppression by Compton drag and Compton cooling by CMB photons. We estimate the gas temperature near the Schwarzschild radius and, hence, the free-free luminosity, accounting for the cooling resulting from collisional ionization when the background gas is mostly neutral. We account approximately for the velocities of PBHs with respect to the background gas. We provide a simple analytic estimate of the efficiency of energy deposition in the plasma. We find that the spectral distortions generated by accreting PBHs are too small to be detected by FIRAS, as well as by future experiments now being considered. We analyze Planck CMB temperature and polarization data and find, under our most conservative hypotheses, and at the order-of-magnitude level, that they rule out PBHs with masses ≳1 0<SUP>2</SUP> M<SUB>⊙</SUB> as the dominant component of dark matter.

[]

https://arxiv.org/pdf/1612.05644.pdf

2000CQGra..17.4175C

Logarithmic corrections to black hole entropy, from the Cardy formula

2000-01-01

['-', '-']

[]

Many recent attempts to calculate black hole entropy from first principles rely on conformal field theory techniques. By examining the logarithmic corrections to the Cardy formula, I compute the first-order quantum correction to the Bekenstein-Hawking entropy in several models, including those based on asymptotic symmetries, horizon symmetries and certain string theories. Despite very different physical assumptions, these models all give a correction proportional to the logarithm of the horizon size, and agree qualitatively with recent results from `quantum geometry' in 3 + 1 dimensions. There are some indications that even the coefficient of the correction may be universal, up to differences that depend on the treatment of angular momentum and conserved charges.

[]

https://arxiv.org/pdf/gr-qc/0005017.pdf

2002MNRAS.337..109M

Measuring the black hole masses of high-redshift quasars

2002-01-01

['galaxies active', 'galaxies fundamental parameters', 'galaxies photometry', 'galaxies nuclei', 'galaxies quasars', 'galaxies quasars', 'astrophysics']

[]

A new technique is presented for determining the black hole masses of high-redshift quasars from optical spectroscopy. The new method utilizes the full-width at half-maximum (FWHM) of the low-ionization MgII emission line and the correlation between the broad-line region (BLR) radius and the continuum luminosity at 3000 Å. Using archival ultraviolet (UV) spectra it is found that the correlation between BLR radius and 3000-Å luminosity is tighter than the established correlation with 5100-Å luminosity. Furthermore, it is found that the correlation between BLR radius and 3000-Å continuum luminosity is consistent with a relation of the form R<SUB>BLR</SUB>~λL<SUP>1/2</SUP><SUB>λ</SUB>, as expected for a constant ionization parameter. Using a sample of objects with broad-line radii determined from reverberation mapping it is shown that the FWHM of MgII and Hβ are consistent with following an exact one-to-one relation, as expected if both Hβ and MgII are emitted at the same radius from the central ionizing source. The resulting virial black hole mass estimator based on rest-frame UV observables is shown to reproduce black hole mass measurements based on reverberation mapping to within a factor of 2.5 (1σ). Finally, the new UV black hole mass estimator is shown to produce identical results to the established optical (Hβ) estimator when applied to 128 intermediate-redshift (0.3 &lt; z &lt; 0.9) quasars drawn from the Large Bright Quasar Survey and the radio-selected Molonglo quasar sample. We therefore conclude that the new UV virial black hole mass estimator can be reliably used to estimate the black hole masses of quasars from z~ 0.25 through to the peak epoch of quasar activity at z~ 2.5 via optical spectroscopy alone.

[]

https://arxiv.org/pdf/astro-ph/0204473.pdf

2003ApJ...595..614W

Self-regulated Growth of Supermassive Black Holes in Galaxies as the Origin of the Optical and X-Ray Luminosity Functions of Quasars

2003-01-01

['black hole physics', 'astrophysics']

[]

We postulate that supermassive black holes grow in the centers of galaxies until they unbind the galactic gas that feeds them. We show that the corresponding self-regulation condition yields a correlation between black hole mass (M<SUB>bh</SUB>) and galaxy velocity dispersion (σ) as inferred in the local universe and recovers the observed optical and X-ray luminosity functions of quasars at redshifts up to z~6 based on the hierarchical evolution of galaxy halos in a Λ-dominated cold dark matter cosmology. With only one free parameter and a simple algorithm, our model yields the observed evolution in the number density of optically bright or X-ray-faint quasars with 2&lt;~z&lt;~6 across 3 orders of magnitude in bolometric luminosity and 3 orders of magnitude in comoving density per logarithm of luminosity. The self-regulation condition identifies the dynamical time of galactic disks during the epoch of peak quasar activity (z~2.5) as the origin of the inferred characteristic quasar lifetime of ~10<SUP>7</SUP> yr. Since the lifetime becomes comparable to the Salpeter e-folding time at this epoch, the model also implies that the M<SUB>bh</SUB>-σ relation is a product of feedback-regulated accretion during the peak of quasar activity. The mass density in black holes accreted by that time is consistent with the local black hole mass density ρ<SUB>bh</SUB>~(2.3<SUP>+4.0</SUP><SUB>-1.5</SUB>)×10<SUP>5</SUP> M<SUB>solar</SUB> Mpc<SUP>-3</SUP>, which we have computed by combining the M<SUB>bh</SUB>-σ relation with the measured velocity dispersion function of Sloan Digital Sky Survey galaxies. Comparison of the local black hole mass function with that inferred from combining the feedback relation with the halo mass function suggests that most massive (&gt;10<SUP>9</SUP> M<SUB>solar</SUB>) black holes may have already been in place by z~6. Applying a similar self-regulation principle to supernova-driven winds from starbursts, we find that the local ratio between the black hole mass and the stellar mass of galactic spheroids should be ~0.001, independent of mass and in agreement with observations. This ratio increases with redshift, although the M<SUB>bh</SUB>-σ relation is redshift-independent.

[]

https://arxiv.org/pdf/astro-ph/0304156.pdf

2007PhRvD..75l4018B

Inspiral, merger, and ring-down of equal-mass black-hole binaries

2007-01-01

['-', '-', '-', '-', 'methods numerical', '-', 'perturbation theory', '-', 'waves', '-', '-', 'astrophysics']

[]

We investigate the dynamics and gravitational-wave (GW) emission in the binary merger of equal-mass black holes as obtained from numerical relativity simulations. The simulations were performed with an evolution code based on generalized harmonic coordinates developed by Pretorius, and used quasiequilibrium initial-data sets constructed by Cook and Pfeiffer. Results from the evolution of three sets of initial data are explored in detail, corresponding to different initial separations of the black holes, and exhibit between 2 8 GW cycles before coalescence. We find that to a good approximation the inspiral phase of the evolution is quasicircular, followed by a “blurred, quasicircular plunge” lasting for about 1 1.5 GW cycles. After this plunge the GW frequency decouples from the orbital frequency, and we define this time to be the start of the merger phase. Roughly 10 15 M separates the time between the beginning of the merger phase and when we are able to extract quasinormal ring-down modes from gravitational waves emitted by the newly formed black hole. This suggests that the merger lasts for a correspondingly short amount of time, approximately 0.5 0.75 of a full GW cycle. We present first-order comparisons between analytical models of the various stages of the merger and the numerical results—more detailed and accurate comparisons will need to await numerical simulations with higher accuracy, better control of systemic errors (including coordinate artifacts), and initial configurations where the binaries are further separated. During the inspiral, we find that if the orbital phase is well modeled, the leading order Newtonian quadrupole formula is able to match both the amplitude and phase of the numerical GW quite accurately until close to the point of merger. We provide comparisons between the numerical results and analytical predictions based on the adiabatic post-Newtonian (PN) and nonadiabatic resummed-PN models (effective-one-body and Padé models). For all models considered, 3PN and 3.5PN orders match the inspiral numerical data the best. From the ring-down portion of the GW, we extract the fundamental quasinormal mode and several of the overtones. Finally, we estimate the optimal signal-to-noise ratio (SNR) for typical binaries detectable by GW experiments. We find that, when the merger and ring-down phases are included, binaries with total mass larger than 40M<SUB>⊙</SUB> (sources for ground-based detectors) are brought in band and can be detected with signal-to-noise up to ≈15 at 100 Mpc, whereas for binaries with total mass larger than 2×10<SUP>6</SUP>M<SUB>⊙</SUB> (sources for space-based detectors) the SNR can be ≈10<SUP>4</SUP> at 1 Gpc.

[]

https://arxiv.org/pdf/gr-qc/0610122.pdf

2010PhRvD..82f4016S

Matching post-Newtonian and numerical relativity waveforms: Systematic errors and a new phenomenological model for nonprecessing black hole binaries

2010-01-01

['-', '-', '-', '-', 'waves', 'methods numerical', '-', 'perturbation theory', '-', '-', '-']

[]

We present a new phenomenological gravitational waveform model for the inspiral and coalescence of nonprecessing spinning black hole binaries. Our approach is based on a frequency-domain matching of post-Newtonian inspiral waveforms with numerical relativity based binary black hole coalescence waveforms. We quantify the various possible sources of systematic errors that arise in matching post-Newtonian and numerical relativity waveforms, and we use a matching criteria based on minimizing these errors; we find that the dominant source of errors are those in the post-Newtonian waveforms near the merger. An analytical formula for the dominant mode of the gravitational radiation of nonprecessing black hole binaries is presented that captures the phenomenology of the hybrid waveforms. Its implementation in the current searches for gravitational waves should allow cross-checks of other inspiral-merger-ringdown waveform families and improve the reach of gravitational-wave searches.

[]

https://arxiv.org/pdf/1005.3306.pdf

2012ApJ...757...27A

Secular Evolution of Compact Binaries near Massive Black Holes: Gravitational Wave Sources and Other Exotica

2012-01-01

['stars binaries close', 'galaxy center', 'gravitational waves', 'stars kinematics and dynamics', '-', '-']

[]

The environment near supermassive black holes (SMBHs) in galactic nuclei contains a large number of stars and compact objects. A fraction of these are likely to be members of binaries. Here we discuss the binary population of stellar black holes and neutron stars near SMBHs and focus on the secular evolution of such binaries, due to the perturbation by the SMBH. Binaries with highly inclined orbits with respect to their orbit around the SMBH are strongly affected by secular Kozai processes, which periodically change their eccentricities and inclinations (Kozai cycles). During periapsis approach, at the highest eccentricities during the Kozai cycles, gravitational wave (GW) emission becomes highly efficient. Some binaries in this environment can inspiral and coalesce at timescales much shorter than a Hubble time and much shorter than similar binaries that do not reside near an SMBH. The close environment of SMBHs could therefore serve as a catalyst for the inspiral and coalescence of binaries and strongly affect their orbital properties. Such compact binaries would be detectable as GW sources by the next generation of GW detectors (e.g., advanced-LIGO). Our analysis shows that ~0.5% of such nuclear merging binaries will enter the LIGO observational window while on orbits that are still very eccentric (e &gt;~ 0.5). The efficient GW analysis for such systems would therefore require the use of eccentric templates. We also find that binaries very close to the SMBH could evolve through a complex dynamical (non-secular) evolution, leading to emission of several GW pulses during only a few years (though these are likely to be rare). Finally, we note that the formation of close stellar binaries, X-ray binaries, and their merger products could be induced by similar secular processes, combined with tidal friction rather than GW emission as in the case of compact object binaries.

[]

https://arxiv.org/pdf/1203.2938.pdf

2001ARA&A..39..309M

The Supermassive Black Hole at the Galactic Center

2001-01-01

['accretion', 'black hole physics', 'gas', 'gas', 'mhd', 'astronomy radio', 'astronomy radio', 'stars kinematics and dynamics', 'astrophysics']

[]

The inner few parsecs at the Galactic Center have come under intense scrutiny in recent years, in part due to the exciting broad-band observations of this region, but also because of the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The Galactic Center is now known to contain arguably the most compelling supermassive black hole candidate, weighing in at a little over 2.6 million suns. Its interaction with the nearby environment, comprised of clusters of evolved and young stars, a molecular dusty ring, ionized gas streamers, diffuse hot gas, and a hypernova remnant, is providing a wealth of accretion phenomenology and high-energy processes for detailed modeling. In this review, we summarize the latest observational results and focus on the physical interpretation of the most intriguing object in this region-the compact radio source Sgr A*, thought to be the radiative manifestation of the supermassive black hole.

[]

https://arxiv.org/pdf/astro-ph/0106162.pdf

2002CQGra..19.2355D

General logarithmic corrections to black-hole entropy

2002-01-01

['-', '-']

[]

We compute leading-order corrections to the entropy of any thermodynamic system due to small statistical fluctuations around equilibrium. When applied to black holes, these corrections are shown to be of the form -k ln(Area). For BTZ black holes, k = 3/2, as found earlier. We extend the result to anti-de Sitter Schwarzschild and Reissner-Nordström black holes in arbitrary dimensions. Finally we examine the role of conformal field theory in black-hole entropy and its corrections.

[]

https://arxiv.org/pdf/hep-th/0111001.pdf

2004PhRvL..93b1102B

Black Hole Mass Decreasing due to Phantom Energy Accretion

2004-01-01

['-', '-', '-', '-', '-', '-', 'cosmology dark matter', 'particles', 'astrophysics', '-']

[]

Solution for a stationary spherically symmetric accretion of the relativistic perfect fluid with an equation of state p(ρ) onto the Schwarzschild black hole is presented. This solution is a generalization of Michel solution and applicable to the problem of dark energy accretion. It is shown that accretion of phantom energy is accompanied by the gradual decrease of the black hole mass. Masses of all black holes tend to zero in the phantom energy Universe approaching the Big Rip.

[]

https://arxiv.org/pdf/gr-qc/0402089.pdf

2008GReGr..40.2249S

Black hole entropy function, attractors and precision counting of microstates

2008-01-01

['string theory', '-', 'thermodynamics', '-', '-']

[]

In these lecture notes we describe recent progress in our understanding of attractor mechanism and entropy of extremal black holes based on the entropy function formalism. We also describe precise computation of the microscopic degeneracy of a class of quarter BPS dyons in {mathcal{N}=4} supersymmetric string theories, and compare the statistical entropy of these dyons, expanded in inverse powers of electric and magnetic charges, with a similar expansion of the corresponding black hole entropy. This comparison is extended to include the contribution to the entropy from multi-centred black holes as well.

[]

https://arxiv.org/pdf/0708.1270.pdf

1995PhLB..353...46L

Three dimensional black holes and cylindrical general relativity

1995-01-01

['-']

[]

A black string solution of the four dimensional Einstein-Hilbert action, S = 1/(16πG) ∫d<SUP>4</SUP>x√-g (R - 2Λ), in a cylindrical spacetime is found. The three dimensional dilaton-gravity theory obtained through dimensional reduction, with action S =1/(2π) ∫ d<SUP>3</SUP>x√-ge<SUP>-2φ</SUP> (R - 2Λ), contains the corresponding three dimensional black hole solution. In this three dimensional theory one is able to define mass and angular momentum for the black hole using the Hamiltonian formulation. The causal structure is analyzed and the temperature of the black hole is computed.

[]

https://arxiv.org/pdf/gr-qc/9404041.pdf

1995MPLA...10.2081S

Extremal Black Holes and Elementary String States

1995-01-01

['-', '-']

[]

Some of the extremal black hole solutions in string theory have the same quantum numbers as the Bogomol’nyi saturated elementary string states. We explore the possibility that these black holes can be identified with elementary string excitations. It is shown that stringy effects could correct the Bekenstein-Hawking formula for the black hole entropy in such a way that it correctly reproduces the logarithm of the density of elementary string states. In particular, this entropy has the correct dependence on three independent parameters, the mass and the left-handed charge of the black hole, and the string coupling constant.

[]

https://arxiv.org/pdf/hep-th/9504147.pdf

2005Ap&SS.300..107H

The Evolution of Black Hole States

2005-01-01

['accretion', 'accretion disks', 'black hole physics', 'astronomy x rays', 'astronomy x rays', 'astrophysics']

[]

We discuss the evolution of black hole transients on the basis of a few systems that were intensively observed with the Rossi X-ray Timing Explorer (rxte). We focus on the global evolution and the observed state transitions. Rather than giving a numerical recipe for classifying observations, we try to identify times during outbursts at which clear changes occur in the X-ray variability, X-ray spectral, or multi-wavelength properties.

[]

https://arxiv.org/pdf/astro-ph/0412597.pdf

2008PhRvD..77l4014V

Time delay and magnification centroid due to gravitational lensing by black holes and naked singularities

2008-01-01

['-', '-', '-', '-', '-', '-', 'black hole physics', '-', '-', 'astrophysics', '-', '-']

[]

We model the massive dark object at the center of the Galaxy as a Schwarzschild black hole as well as Janis-Newman-Winicour naked singularities, characterized by the mass and scalar charge parameters, and study gravitational lensing (particularly time delay, magnification centroid, and total magnification) by them. We find that the lensing features are qualitatively similar (though quantitatively different) for Schwarzschild black holes, weakly naked, and marginally strongly naked singularities. However, the lensing characteristics of strongly naked singularities are qualitatively very different from those due to Schwarzschild black holes. The images produced by Schwarzschild black hole lenses and weakly naked and marginally strongly naked singularity lenses always have positive time delays. On the other hand, strongly naked singularity lenses can give rise to images with positive, zero, or negative time delays. In particular, for a large angular source position the direct image (the outermost image on the same side as the source) due to strongly naked singularity lensing always has a negative time delay. We also found that the scalar field decreases the time delay and increases the total magnification of images; this result could have important implications for cosmology. As the Janis-Newman-Winicour metric also describes the exterior gravitational field of a scalar star, naked singularities as well as scalar star lenses, if these exist in nature, will serve as more efficient cosmic telescopes than regular gravitational lenses.

[]

https://arxiv.org/pdf/0710.2333.pdf

2020A&A...636A.104B

Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes

2020-01-01

['-', 'black hole physics', 'gravitational waves', '-', '-']

[]

All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported following the O1/O2 runs have near-zero effective spins. There are only three potential explanations for this. If the BH spin magnitudes are large, then: (i) either both BH spin vectors must be nearly in the orbital plane or (ii) the spin angular momenta of the BHs must be oppositely directed and similar in magnitude. Then there is also the possibility that (iii) the BH spin magnitudes are small. We consider the third hypothesis within the framework of the classical isolated binary evolution scenario of the BH-BH merger formation. We test three models of angular momentum transport in massive stars: a mildly efficient transport by meridional currents (as employed in the Geneva code), an efficient transport by the Tayler-Spruit magnetic dynamo (as implemented in the MESA code), and a very-efficient transport (as proposed by Fuller et al.) to calculate natal BH spins. We allow for binary evolution to increase the BH spins through accretion and account for the potential spin-up of stars through tidal interactions. Additionally, we update the calculations of the stellar-origin BH masses, including revisions to the history of star formation and to the chemical evolution across cosmic time. We find that we can simultaneously match the observed BH-BH merger rate density and BH masses and BH-BH effective spins. Models with efficient angular momentum transport are favored. The updated stellar-mass weighted gas-phase metallicity evolution now used in our models appears to be key for obtaining an improved reproduction of the LIGO/Virgo merger rate estimate. Mass losses during the pair-instability pulsation supernova phase are likely to be overestimated if the merger GW170729 hosts a BH more massive than 50 M<SUB>⊙</SUB>. We also estimate rates of black hole-neutron star (BH-NS) mergers from recent LIGO/Virgo observations. If, in fact. angular momentum transport in massive stars is efficient, then any (electromagnetic or gravitational wave) observation of a rapidly spinning BH would indicate either a very effective tidal spin up of the progenitor star (homogeneous evolution, high-mass X-ray binary formation through case A mass transfer, or a spin- up of a Wolf-Rayet star in a close binary by a close companion), significant mass accretion by the hole, or a BH formation through the merger of two or more BHs (in a dense stellar cluster). <P />Our updated models of BH-BH, BH-NS and NS-NS mergers are now publicly available at <A href="http://www.syntheticuniverse.org">http://www.syntheticuniverse.org</A> under the tab "Download/2020: Double Compact Objects/&lt;xref ref-type="bibr" rid="R29"&gt;http://Belczynski et al. 2020&lt;/xref&gt;http://"

[]

https://arxiv.org/pdf/1706.07053.pdf

2014SSRv..183..277R

Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy

2014-01-01

['accretion disks', 'black hole physics', 'astronomy x rays', '-', '-']

[]

I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on "best practices" that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high ( M&gt;5×10<SUP>7</SUP> M <SUB>⊙</SUB>) and low ( M&lt;2×10<SUP>6</SUP> M <SUB>⊙</SUB>) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GRO J1655-40 and 4U 1543-475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC 4151, NGC 7314 and MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.

[]

https://arxiv.org/pdf/1302.3260.pdf

2014PhRvD..89f1502T

Effective-one-body model for black-hole binaries with generic mass ratios and spins

2014-01-01

['-', '-', '-', '-', 'methods numerical', 'methods numerical', '-', 'perturbation theory', '-', '-', '-']

[]

Gravitational waves emitted by black-hole binary systems have the highest signal-to-noise ratio in LIGO and Virgo detectors when black-hole spins are aligned with the orbital angular momentum and extremal. For such systems, we extend the effective-one-body inspiral-merger-ringdown waveforms to generic mass ratios and spins calibrating them to 38 numerical-relativity nonprecessing waveforms produced by the SXS Collaboration. The numerical-relativity simulations span mass ratios from 1 to 8, spin magnitudes up to 98% of extremality, and last for 40 to 60 gravitational-wave cycles. When the total mass of the binary is between 20 and 200M<SUB>⊙</SUB>, the effective-one-body nonprecessing (dominant mode) waveforms have overlap above 99% (using the advanced-LIGO design noise spectral density) with all of the 38 nonprecessing numerical waveforms, when maximizing only on initial phase and time. This implies a negligible loss in event rate due to modeling. We also show that—without further calibration— the precessing effective-one-body (dominant mode) waveforms have overlap above 97% with two very long, strongly precessing numerical-relativity waveforms, when maximizing only on the initial phase and time.

[]

https://arxiv.org/pdf/1311.2544.pdf

2021PhRvD.103j4056P

Computationally efficient models for the dominant and subdominant harmonic modes of precessing binary black holes

2021-01-01

['-']

[]

We present IMRPhenomXPHM, a phenomenological frequency-domain model for the gravitational-wave signal emitted by quasicircular precessing binary black holes, which incorporates multipoles beyond the dominant quadrupole in the precessing frame. The model is a precessing extension of IMRPhenomXHM, [C. García-Quirós et al., Phys. Rev. D 102, 064002 (2020), 10.1103/PhysRevD.102.064002] based on approximate maps between aligned-spin waveform modes in the coprecessing frame and precessing waveform modes in the inertial frame, which is commonly referred to as "twisting up" the nonprecessing waveforms. IMRPhenomXHXPHMncludes IMRPhenomXP as a special case, the restriction to the dominant quadrupole contribution in the coprecessing frame. We implement two alternative mappings, one based on a single-spin post-Newtonian approximation, as used in IMRPhenomPv2 [M. Hannam et al., Phys. Rev. Lett. 113, 151101 (2014)., 10.1103/PhysRevLett.113.151101], and one based on the double-spin multiple scale analysis approach of [K. Chatziioannou et al., Phys. Rev. D 95, 104004 (2017)., 10.1103/PhysRevD.95.104004]. We include a detailed discussion of conventions used in the description of precessing binaries and of all choices made in constructing the model. The computational cost of IMRPhenomXPHM is further reduced by extending the interpolation technique of [C. García-Quirós et al., Classical Quant. Grav. 38, 015006 (2021)., 10.1088/1361-6382/abc36e] to the Euler angles. The accuracy, speed, robustness, and modularity of the IMRPhenomX family will make these models productive tools for gravitational wave astronomy in the current era of greatly increased number and diversity of detected events.

[]

https://arxiv.org/pdf/2004.06503.pdf

1992PhRvL..69.1006S

Rotating charged black hole solution in heterotic string theory.

1992-01-01

['black hole physics', 'theory', '-', 'string theory', 'angular momentum', 'charge', '-', 'stars luminosity function;mass function', '-', '-', '-', '-', 'black hole physics', '-']

[]

The author constructs a solution of the classical equations of motion arising in the low-energy effective field theory for heterotic string theory. This solution describes a black hole in four dimensions carrying mass M, charge Q, and angular momentum J. The extremal limit of the solution is discussed.

[]

https://arxiv.org/pdf/hep-th/9204046.pdf

1998tbha.conf..148N

Advection-dominated accretion around black holes

1998-01-01

['black hole physics', 'astronomy x rays', 'galaxies active', 'astrophysics', '-']

[]

This article reviews the physics of advection-dominated accretion flows (ADAFs) and describes applications to several black hole X-ray binaries and galactic nulcei. The possibility of using ADAFs to explore the event horizons of black holes is highlighted.

[]

https://arxiv.org/pdf/astro-ph/9803141.pdf

1999PhR...319....1V

Gravitating non-Abelian solitons and black holes with Yang-Mills fields

1999-01-01

['-', '-', '-']

[]

We present a review of gravitating particle-like and black hole solutions with non-Abelian gauge fields. The emphasis is given to the description of the structure of the solutions and to the connection with the results of flat space soliton physics. We describe the Bartnik-McKinnon solitons and the non-Abelian black holes arising in the Einstein-Yang-Mills theory, and consider their various generalizations. These include axially symmetric and slowly rotating configurations, solutions with higher gauge groups, Λ-term, dilaton, and higher curvature corrections. The stability issue is discussed as well. We also describe the gravitating generalizations for flat space monopoles, sphalerons, and Skyrmions.

[]

https://arxiv.org/pdf/hep-th/9810070.pdf

2002ApJ...571..733V

Determining Central Black Hole Masses in Distant Active Galaxies

2002-01-01

['galaxies active', 'galaxies fundamental parameters', 'galaxies photometry', 'galaxies seyfert', 'galaxies quasars', 'astronomy uv', 'astrophysics']

[]

An empirical relationship, of particular interest for studies of high-redshift active galactic nuclei (AGNs) and quasars, between the masses of their central black holes and rest-frame ultraviolet (UV) parameters measured in single-epoch AGN spectra is presented. This relationship is calibrated to recently measured reverberation masses of low-redshift AGNs and quasars. An empirical relationship between single-epoch rest-frame optical spectrophotometric measurements and the central masses is also presented. The UV relationship allows reasonable estimates of the central masses to be made for high-redshift AGNs and quasars for which these masses cannot be directly or easily measured by the techniques applicable to the lower luminosity, nearby AGNs. The central mass obtained by this method can be estimated to within a factor of ~3 for most objects. This is reasonable given the intrinsic uncertainty of a factor of less than 2 in the primary methods used to measure the central masses of nearby inactive and active galaxies, namely, resolved gas and stellar kinematics in the underlying host galaxy and reverberation-mapping techniques. The UV relationship holds good potential for being a powerful tool for studying black hole demographics at high redshift as well as statistically studying the fundamental properties of AGNs. The broad-line region size-luminosity relationship is key to the calibrations presented here. The fact that its intrinsic scatter is also the main source of uncertainty in the calibrations stresses the need for better observational constraints to be placed on this relationship. The empirically calibrated relationships presented here will be applied to quasar samples in forthcoming work.

[]

https://arxiv.org/pdf/astro-ph/0204106.pdf

2009ApJ...705..199B

The Lick AGN Monitoring Project: Broad-line Region Radii and Black Hole Masses from Reverberation Mapping of Hβ

2009-01-01

['galaxies active', 'galaxies nuclei', 'galaxies seyfert', '-']

[]

We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z &lt; 0.05) Seyfert 1 galaxies with expected masses in the range ~10<SUP>6</SUP>-10<SUP>7</SUP> M <SUB>sun</SUB> and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hβ emission. We present here the light curves for all the objects in this sample and the subsequent Hβ time lags for the nine objects where these measurements were possible. The Hβ lag time is directly related to the size of the broad-line region (BLR) in AGNs, and by combining the Hβ lag time with the measured width of the Hβ emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local M <SUB>BH</SUB>-σ<SUB>sstarf</SUB>relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hβ line profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting BLR clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on the physical models of the BLR by the velocity-resolved response in these objects.

[]

https://arxiv.org/pdf/0908.0003.pdf

2000PhRvL..85..499E

Black Holes Radiate Mainly on the Brane

2000-01-01

['-', '-', '-']

[]

We examine the evaporation of a small black hole on a brane in a world with large extra dimensions. Since the masses of many Kaluza-Klein modes are much smaller than the Hawking temperature of the black hole, it has been claimed that most of the energy is radiated into these modes. We show that this is incorrect. Most of the energy goes into the modes on the brane. This raises the possibility of observing Hawking radiation in future high energy colliders if there are large extra dimensions.

[]

https://arxiv.org/pdf/hep-th/0003118.pdf

2011ApJ...729..119G

The Black Hole Mass in M87 from Gemini/NIFS Adaptive Optics Observations

2011-01-01

['galaxies elliptical lenticular;cd', 'cd', 'galaxies', 'galaxies kinematics and dynamics', '-']

[]

We present the stellar kinematics in the central 2'' of the luminous elliptical galaxy M87 (NGC 4486), using laser adaptive optics to feed the Gemini telescope integral-field spectrograph, Near-infrared Integral Field Spectrograph (NIFS). The velocity dispersion rises to 480 km s<SUP>-1</SUP> at 0farcs2. We combine these data with extensive stellar kinematics out to large radii to derive a black hole mass equal to (6.6 ± 0.4) × 10<SUP>9</SUP> M <SUB>sun</SUB>, using orbit-based axisymmetric models and including only the NIFS data in the central region. Including previously reported ground-based data in the central region drops the uncertainty to 0.25 × 10<SUP>9</SUP> M <SUB>sun</SUB> with no change in the best-fit mass; however, we rely on the values derived from the NIFS-only data in the central region in order to limit systematic differences. The best-fit model shows a significant increase in the tangential velocity anisotropy of stars orbiting in the central region with decreasing radius, similar to that seen at the centers of other core galaxies. The black hole mass is insensitive to the inclusion of a dark halo in the models—the high angular resolution provided by the adaptive optics breaks the degeneracy between black hole mass and stellar mass-to-light ratio. The present black hole mass is in excellent agreement with the Gebhardt &amp; Thomas value, implying that the dark halo must be included when the kinematic influence of the black hole is poorly resolved. This degeneracy implies that the black hole masses of luminous core galaxies, where this effect is important, may need to be re-evaluated. The present value exceeds the prediction of the black hole-dispersion and black hole-luminosity relations, both of which predict about 1 × 10<SUP>9</SUP> M <SUB>sun</SUB> for M87, by close to twice the intrinsic scatter in the relations. The high end of the black hole correlations may be poorly determined at present.

[]

https://arxiv.org/pdf/1101.1954.pdf

2007PhRvL..98i1101G

Maximum Kick from Nonspinning Black-Hole Binary Inspiral

2007-01-01

['-', '-', '-', '-', 'methods numerical', 'waves', '-', '-', '-', 'astrophysics']

[]

When unequal-mass black holes merge, the final black hole receives a kick due to the asymmetric loss of linear momentum in the gravitational radiation emitted during the merger. The magnitude of this kick has important astrophysical consequences. Recent breakthroughs in numerical relativity allow us to perform the largest parameter study undertaken to date in numerical simulations of binary black-hole inspirals. We study nonspinning black-hole binaries with mass ratios from q=M<SUB>1</SUB>/M<SUB>2</SUB>=1 to q=0.25 (η=q/(1+q)<SUP>2</SUP> from 0.25 to 0.16). We accurately calculate the velocity of the kick to within 6%, and the final spin of the black holes to within 2%. A maximum kick of 175.2±11kms<SUP>-1</SUP> is achieved for η=0.195±0.005.

[]

https://arxiv.org/pdf/gr-qc/0610154.pdf

2004JHEP...04..048G

General supersymmetric AdS<SUB>5</SUB> black holes

2004-01-01

['black hole physics', '-', '-']

[]

Supersymmetric, asymptotically AdS<SUB>5</SUB>, black hole solutions of five dimensional gauged supergravity coupled to arbitrarily many abelian vector multiplets are presented. The general nature of supersymmetric solutions of this theory is discussed. All maximally supersymmetric solutions of this theory (with or without gauging) are obtained.

[]

https://arxiv.org/pdf/hep-th/0401129.pdf

2009PhRvD..79h3004V

Relativistic images of Schwarzschild black hole lensing

2009-01-01

['-', '-', '-', '-', '-', '-', '-', 'astrophysics', '-']

[]

We model massive dark objects at centers of many galaxies as Schwarzschild black hole lenses and study gravitational lensing by them in detail. We show that the ratio of mass of a Schwarzschild lens to the differential time delay between outermost two relativistic images (both of them either on the primary or on the secondary image side) is extremely insensitive to changes in the angular source position as well as the lens-source and lens-observer distances. Therefore, this ratio can be used to obtain very accurate values for masses of black holes at centers of galaxies. Similarly, angular separations between any two relativistic images are also extremely insensitive to changes in the angular source position and the lens-source distance. Therefore, with the known value of mass of a black hole, angular separation between two relativistic images would give a very accurate result for the distance of the black hole. Accuracies in determination of masses and distances of black holes would however depend on accuracies in measurements of differential time delays and angular separations between images. Deflection angles of primary and secondary images as well as effective deflection angles of relativistic images on the secondary image side are always positive. However, the effective deflection angles of relativistic images on the primary image side may be positive, zero, or negative depending on the value of angular source position and the ratio of mass of the lens to its distance. We show that effective deflection angles of relativistic images play significant role in analyzing and understanding strong gravitational field lensing.

[]

https://arxiv.org/pdf/0810.2109.pdf

2013Natur.501..391E

A strong magnetic field around the supermassive black hole at the centre of the Galaxy

2013-01-01

['-', '-']

[]

Earth's nearest candidate supermassive black hole lies at the centre of the Milky Way. Its electromagnetic emission is thought to be powered by radiatively inefficient accretion of gas from its environment, which is a standard mode of energy supply for most galactic nuclei. X-ray measurements have already resolved a tenuous hot gas component from which the black hole can be fed. The magnetization of the gas, however, which is a crucial parameter determining the structure of the accretion flow, remains unknown. Strong magnetic fields can influence the dynamics of accretion, remove angular momentum from the infalling gas, expel matter through relativistic jets and lead to synchrotron emission such as that previously observed. Here we report multi-frequency radio measurements of a newly discovered pulsar close to the Galactic Centre and show that the pulsar's unusually large Faraday rotation (the rotation of the plane of polarization of the emission in the presence of an external magnetic field) indicates that there is a dynamically important magnetic field near the black hole. If this field is accreted down to the event horizon it provides enough magnetic flux to explain the observed emission--from radio to X-ray wavelengths--from the black hole.

[]

https://arxiv.org/pdf/1308.3147.pdf

2013PhLB..721..329B

Rotating regular black holes

2013-01-01

['-', '-']

[]

The formation of spacetime singularities is a quite common phenomenon in General Relativity and it is regulated by specific theorems. It is widely believed that spacetime singularities do not exist in Nature, but that they represent a limitation of the classical theory. While we do not yet have any solid theory of quantum gravity, toy models of black hole solutions without singularities have been proposed. So far, there are only non-rotating regular black holes in the literature. These metrics can be hardly tested by astrophysical observations, as the black hole spin plays a fundamental role in any astrophysical process. In this Letter, we apply the Newman-Janis algorithm to the Hayward and to the Bardeen black hole metrics. In both cases, we obtain a family of rotating solutions. Every solution corresponds to a different matter configuration. Each family has one solution with special properties, which can be written in Kerr-like form in Boyer-Lindquist coordinates. These special solutions are of Petrov type D, they are singularity free, but they violate the weak energy condition for a non-vanishing spin and their curvature invariants have different values at r=0 depending on the way one approaches the origin. We propose a natural prescription to have rotating solutions with a minimal violation of the weak energy condition and without the questionable property of the curvature invariants at the origin.

[]

https://arxiv.org/pdf/1302.6075.pdf

1994PhRvD..50.6394B

Temperature, energy, and heat capacity of asymptotically anti-de Sitter black holes

1994-01-01

['-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-']

[]

We investigate the thermodynamical properties of black holes in (3+1)- and (2+1)-dimensional Einstein gravity with a negative cosmological constant. In each case, ther thermodynamic internal energy is computed for a finite spatial region that contains the black hole. The temperature at the boundary of this regoin is defined by differentiating the energy with respect to entropy, and is equal to the product of the surface gravity (divided by 2π) and the Tolman redshift factor for temperature in a stationary gravitational field. We also compute the thermodynamic surface pressure and, in the case of the 2+1 black hole, show that the chemical potential conjugate to angular momentum is equal to the proper angular velocity of the black hole with respect to observers who are at rest in the stationary time slices. In 3+1 dimensions, a calculation of the heat capacity reveals the existence of a thermodynamically stable black hole solution and a negative heat capacity instanton. This result holds in the limit that the spatial boundary tends to infinity only if the cosmological constant is negative; if the cosmological constant vanishes, the stable black hole solution is lost. In 2+1 dimensions, a calculation of the heat capacity reveals the existence of a thermodynamically stable black hole solution, but no negative heat capacity instanton.

[]

https://arxiv.org/pdf/gr-qc/9405007.pdf

2008NewAR..51..733N

Advection-dominated accretion and the black hole event horizon

2008-01-01

['astrophysics']

[]

As the luminosity of an accreting black hole drops to a few percent of Eddington, the spectrum switches from the familiar soft state to a hard state that is well-described by a distended and tenuous advection-dominated accretion flow (ADAF). An ADAF is a poor radiator, and the ion temperature can approach 10<SUP>12</SUP> K near the center, although the electrons are cooler, with their temperature typically capped at ∼10 K. The foundational papers predicted that the large thermal energy in an ADAF would drive strong winds and jets, as later observed and also confirmed in computer simulations. Of chief interest, however, is the accreting gas that races inward. It carries the bulk of the accretion energy as stored thermal energy, which vanishes without a trace as the gas passes through the hole's event horizon. One thus expects black holes in the ADAF regime to be unusually faint. Indeed, this is confirmed by a comparison of accreting stellar-mass black holes and neutron stars, which reside in very similar transient X-ray binary systems. The black holes are on average observed to be fainter by a factor of ∼100-1000. The natural explanation is that a neutron star must radiate the advected thermal energy from its surface, whereas a black hole can hide the energy behind its event horizon. The case for an event horizon in Sagittarius A <SUP>∗</SUP>, which is immune to caveats on jet outflows and is furthermore independent of the ADAF model, is especially compelling. These two lines of evidence for event horizons are impervious to counterarguments that invoke strong gravity or exotic stars.

[]

https://arxiv.org/pdf/0803.0322.pdf

2004CQGra..21.1135V

Stable gravastars—an alternative to black holes?

2004-01-01

['-', 'astrophysics', '-']

[]

The 'gravastar' picture developed by Mazur and Mottola is one of a very small number of serious challenges to our usual conception of a 'black hole'. In the gravastar picture there is effectively a phase transition at/near where the event horizon would have been expected to form, and the interior of what would have been the black hole is replaced by a segment of de Sitter space. While Mazur and Mottola were able to argue for the thermodynamic stability of their configuration, the question of dynamic stability against spherically symmetric perturbations of the matter or gravity fields remains somewhat obscure. In this paper we construct a model that shares the key features of the Mazur Mottola scenario, and which is sufficiently simple for a full dynamical analysis. We find that there are some physically reasonable equations of state for the transition layer that lead to stability.

[]

https://arxiv.org/pdf/gr-qc/0310107.pdf

1995PhRvD..52.4430I

Comparison of the Noether charge and Euclidean methods for computing the entropy of stationary black holes

1995-01-01

['-', '-', '-', 'black hole physics', '-', '-']

[]

The entropy of stationary black holes has recently been calculated by a number of different approaches. Here we compare the Noether charge approach (defined for any diffeomorphism invariant Lagrangian theory) with various Euclidean methods, specifically, (i) the microcanonical ensemble approach of Brown and York, (ii) the closely related approach of Bañados, Teitelboim, and Zanelli which ultimately expresses black hole entropy in terms of the Hilbert action surface term, (iii) another formula of Bañados, Tetelboim, and Zanelli (also used by Susskind and Uglum) which views black hole entropy as conjugate to a conical deficit angle, and (iv) the pair creation approach of Garfinkle, Giddings, and Strominger. All of these approaches have a more restrictive domain of applicability than the Noether charge approach. Specifically, approaches (i) and (ii) appear to be restricted to a class of theories satisfying certain properties litsed in Sec. II; approach (iii) appears to require the choice of a ``regularizing'' scheme to deal with curvature singularities (except in the case of Lovelock gravity theories), and approach (iv) requires the existence of suitable instanton solutions. However, we show that within their domains of applicability, all of these approaches yield results in agreement with the Noether charge approach. In the course of our analysis we generalize the definition of the Brown-York quasilocal energy to a much more general class of diffeomorphism invariant, Lagrangian theories of gravity. In an appendix we show that in an arbitrary diffeomorphism invariant theory of gravity the ``volume term'' in the ``off-shell'' Hamiltonian associated with a time evolution vector field t<SUP>a</SUP> always can be expressed as the spatial integral of t<SUP>a</SUP>scrC<SUB>a</SUB>, where scrC<SUB>a</SUB>=0 are the constraints associated with the diffeomorphism invariance.

[]

https://arxiv.org/pdf/gr-qc/9503052.pdf

2006ApJ...648..128K

Black Hole Masses and Eddington Ratios at 0.3 &lt; z &lt; 4

2006-01-01

['galaxies active', 'galaxies nuclei', 'surveys', 'astrophysics']

[]

We study the distribution of Eddington luminosity ratios, L<SUB>bol</SUB>/L<SUB>Edd</SUB>, of active galactic nuclei (AGNs) discovered in the AGN and Galaxy Evolution Survey (AGES). We combine Hβ, Mg II, and C IV line widths with continuum luminosities to estimate black hole (BH) masses in 407 AGNs, covering the redshift range z~0.3-4 and the bolometric luminosity range L<SUB>bol</SUB>~10<SUP>45</SUP>-10<SUP>47</SUP> ergs s<SUP>-1</SUP>. The sample consists of X-ray or mid-infrared (24 μm) point sources with optical magnitude R&lt;=21.5 mag and optical emission-line spectra characteristic of AGNs. For the range of luminosity and redshift probed by AGES, the distribution of estimated Eddington ratios is well described as log-normal, with a peak at L<SUB>bol</SUB>/L<SUB>Edd</SUB>~=1/4 and a dispersion of 0.3 dex. Since additional sources of scatter are minimal, this dispersion must account for contributions from the scatter between estimated and true BH mass and the scatter between estimated and true bolometric luminosity. Therefore, we conclude that (1) neither of these sources of error can contribute more than ~0.3 dex rms, and (2) the true Eddington ratios of optically luminous AGNs are even more sharply peaked. Because the mass estimation errors must be smaller than ~0.3 dex, we can also investigate the distribution of Eddington ratios at fixed BH mass. We show for the first time that the distribution of Eddington ratios at fixed BH mass is peaked, and that the dearth of AGNs at a factor of ~10 below Eddington is real and not an artifact of sample selection. These results provide strong evidence that supermassive BHs gain most of their mass while radiating close to the Eddington limit, and they suggest that the fueling rates in luminous AGNs are ultimately determined by BH self-regulation of the accretion flow rather than galactic-scale dynamical disturbances. <P />Observations reported here were obtained at the MMT Observatory (MMTO), a joint facility of the University of Arizona and the Smithsonian Institution.

[]

https://arxiv.org/pdf/astro-ph/0508657.pdf

2007ApJ...662..808L

The Masses of Nuclear Black Holes in Luminous Elliptical Galaxies and Implications for the Space Density of the Most Massive Black Holes

2007-01-01

['black hole physics', 'galaxies nuclei', 'galaxies structure', 'astrophysics']

[]

Black hole (BH) masses predicted from the M<SUB>•</SUB>-σ relationship conflict with predictions from the M<SUB>•</SUB>-L relationship for high-luminosity galaxies, such as brightest cluster galaxies (BCGs). The M<SUB>•</SUB>-L relationship predicts that some BCGs may harbor BHs with M<SUB>•</SUB> approaching 10<SUP>10</SUP> M<SUB>solar</SUB>, while the M<SUB>•</SUB>-σ relationship always predicts M<SUB>•</SUB>&lt;3×10<SUP>9</SUP> M<SUB>solar</SUB>. We argue that the M<SUB>•</SUB>-L relationship is a plausible description for galaxies of high luminosity. If the cores in central stellar density are formed by binary BHs, the inner core cusp radius, r<SUB>γ</SUB>, may be an independent witness of M<SUB>•</SUB>. Using central structural parameters derived from a large sample of early-type galaxies observed by HST, we argue that L is superior to σ as an indicator of r<SUB>γ</SUB>. Further, the r<SUB>γ</SUB>-M<SUB>•</SUB> relationship for 11 core galaxies with measured M<SUB>•</SUB> appears to be consistent with the M<SUB>•</SUB>-L relationship for BCGs. BCGs have large cores appropriate for their large luminosities that may be difficult to generate with the more modest BH masses inferred from the M<SUB>•</SUB>-σ relationship. M<SUB>•</SUB>~M would be expected for BCGs, if they were formed in dissipationless mergers, which should preserve the ratio of BH to stellar mass, M. This scenario appears to be consistent with the slow increase in σ with L and the more rapid increase in effective radii with L seen in BCGs as compared to less luminous galaxies. If BCGs have large BHs commensurate with their luminosities, then the local BH mass function for M<SUB>•</SUB>&gt;3×10<SUP>9</SUP> M<SUB>solar</SUB> would be nearly an order of magnitude richer than that inferred from the M<SUB>•</SUB>-σ relationship. The volume density of the most luminous QSOs may favor the M<SUB>•</SUB>-L relationship. <P />Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with GO and GTO proposals 5236, 5446, 5454, 5512, 5943, 5990, 5999, 6099, 6386, 6554, 6587, 6633, 7468, 8683, and 9107.

[]

https://arxiv.org/pdf/astro-ph/0606739.pdf

2019PhRvD.100b4018G

Black hole shadows, photon rings, and lensing rings

2019-01-01

['-', '-']

[]

The presence of a bright "photon ring" surrounding a dark "black hole shadow" has been discussed as an important feature of the observational appearance of emission originating near a black hole. We clarify the meaning and relevance of these heuristics with analytic calculations and numerical toy models. The standard usage of the term "shadow" describes the appearance of a black hole illuminated from all directions, including from behind the observer. A backlit black hole casts a somewhat larger shadow. Neither "shadow" heuristic is particularly relevant to understanding the appearance of emission originating near the black hole, where the emission profile and gravitational redshift play the dominant roles in determining the observed size of the central dark area. A photon ring results from light rays that orbit around the black hole in the near-field region before escaping to infinity, where they arrive near a ring-shaped "critical curve" on the image plane. Although the brightness can become arbitrarily large near this critical curve in the case of optically thin emitting matter near the black hole, we show that the enhancement is only logarithmic, and hence is of no relevance to present observations. For optically thin emission from a geometrically thin or thick disk, photons that make only a fraction of an orbit will generically give rise to a much wider "lensing ring," which is a demagnified image of the back of the disk, superimposed on top of the direct emission. For nearly face-on viewing, the lensing ring is centered at a radius ∼5 % larger than the photon ring and, depending on the details of the emission, its width is ∼0.5 - 1 M (where M is the mass of the black hole). It can be relatively brighter by a factor of 2-3, as compared to the surrounding parts of the image, and thus could provide a significant feature in high-resolution images. Nevertheless, the characteristic features of the observed image are dominated by the location and properties of the emitting matter near the black hole. We comment on the recent M87* Event Horizon Telescope observations and mass measurement.

[]

https://arxiv.org/pdf/1906.00873.pdf

1997ApJ...482L..29M

Poynting Jets from Black Holes and Cosmological Gamma-Ray Bursts

1997-01-01

['gamma rays', 'black hole physics', 'stars magnetic fields', 'black hole physics', 'gamma rays', 'stars magnetic fields', 'astrophysics']

[]

We discuss the properties of magnetically dominated jetlike outflows from stellar mass black holes surrounded by debris tori resulting from neutron star disruption. These jets may have narrow cores (along the rotation axis) that are almost free of baryons and attain very high bulk Lorentz factors &gt;~10<SUP>6</SUP>. The jets give rise to a characteristic MeV to TeV emission as well as to relativistic shocks producing the usual MeV bursts. Because the outflow is highly directional, the properties of the observed gamma rays would depend on the viewing angle relative to the rotation axis. Even for the most intense bursts, which under the assumption of isotropic emission and substantial redshifts would be inferred to emit 10<SUP>52</SUP>-10<SUP>53</SUP> ergs, the efficiencies required are only 10<SUP>-2</SUP> to 10<SUP>-4</SUP>.

[]

https://arxiv.org/pdf/astro-ph/9609065.pdf

1999MNRAS.309..447M

Rates of tidal disruption of stars by massive central black holes

1999-01-01

['astrophysics']

[]

There is strong evidence for some kind of massive dark object in the centres of many galaxy bulges. The detection of flares from tidally disrupted stars could confirm that these objects are black holes (BHs). Here we present calculations of the stellar disruption rates in detailed dynamical models of real galaxies, taking into account the refilling of the loss cone of stars on disruptable orbits by two-body relaxation and tidal forces in non-spherical galaxies. The highest disruption rates (one star per 10<SUP>4</SUP>yr) occur in faint (L&lt;~10<SUP>10</SUP>L<SUB>solar</SUB>) galaxies, which have steep central density cusps. More luminous galaxies are less dense and have much longer relaxation times and more massive BHs. Dwarf stars in such galaxies are swallowed whole by the BH and hence do not emit flares; giant stars could produce flares as often as every 10<SUP>5</SUP>yr, although the rate depends sensitively on the shape of the stellar distribution function. We discuss the possibility of detecting disruption flares in current supernova searches. The total mass of stars consumed over the lifetime of the galaxy is of the order of 10<SUP>6</SUP>M<SUB>solar</SUB>, independent of galaxy luminosity; thus, disrupted stars may contribute significantly to the present BH mass in galaxies fainter than ~10<SUP>9</SUP>L<SUB>solar</SUB>.

[]

https://arxiv.org/pdf/astro-ph/9902032.pdf

2008PhRvD..77j4017A

Template bank for gravitational waveforms from coalescing binary black holes: Nonspinning binaries

2008-01-01

['-', '-', '-', 'methods numerical', '-', 'perturbation theory', '-', 'waves', '-', 'astrophysics']

[]

Gravitational waveforms from the inspiral and ring-down stages of the binary black-hole coalescences can be modeled accurately by approximation/perturbation techniques in general relativity. Recent progress in numerical relativity has enabled us to model also the nonperturbative merger phase of the binary black-hole coalescence problem. This enables us to coherently search for all three stages of the coalescence of nonspinning binary black holes using a single template bank. Taking our motivation from these results, we propose a family of template waveforms which can model the inspiral, merger, and ring-down stages of the coalescence of nonspinning binary black holes that follow quasicircular inspiral. This two-dimensional template family is explicitly parametrized by the physical parameters of the binary. We show that the template family is not only effectual in detecting the signals from black-hole coalescences, but also faithful in estimating the parameters of the binary. We compare the sensitivity of a search (in the context of different ground-based interferometers) using all three stages of the black-hole coalescence with other template-based searches which look for individual stages separately. We find that the proposed search is significantly more sensitive than other template-based searches for a substantial mass range, potentially bringing about remarkable improvement in the event rate of ground-based interferometers. As part of this work, we also prescribe a general procedure to construct interpolated template banks using nonspinning black-hole waveforms produced by numerical relativity.

[]

https://arxiv.org/pdf/0710.2335.pdf

2017PhRvD..96b3514C

Primordial black hole constraints for extended mass functions

2017-01-01

['-', '-']

[]

We revisit the cosmological and astrophysical constraints on the fraction of the dark matter in primordial black holes (PBHs) with an extended mass function. We consider a variety of mass functions, all of which are described by three parameters: a characteristic mass and width and a dark matter fraction. Various observations then impose constraints on the dark matter fraction as a function of the first two parameters. We show how these constraints relate to those for a monochromatic mass function, demonstrating that they usually become more stringent in the extended case than the monochromatic one. Considering only the well-established bounds, and neglecting the ones that depend on additional astrophysical assumptions, we find that there are three mass windows, around 5 ×10<SUP>-16</SUP>M<SUB>⊙</SUB> , 2 ×10<SUP>-14</SUP>M<SUB>⊙</SUB> and 25 - 100 M<SUB>⊙</SUB> , where PBHs can constitute all the dark matter. However, if one includes all the bounds, PBHs can only constitute of order 10% of the dark matter.

[]

https://arxiv.org/pdf/1705.05567.pdf

2007ARA&A..45..441M

Relativistic X-Ray Lines from the Inner Accretion Disks Around Black Holes

2007-01-01

['astrophysics']

[]

Relativistic X-ray emission lines from the inner accretion disks around black holes are reviewed. Recent observations with the Chandra X-ray Observatory, X-ray Multi-Mirror Mission-Newton, and Suzaku are revealing these lines to be good probes of strong gravitational effects. A number of important observational and theoretical developments are highlighted, including evidence of black hole spin and effects such as gravitational light bending, the detection of relativistic lines in stellar-mass black holes, and evidence of orbital-timescale line flux variability. In addition, the robustness of the relativistic disk lines against absorption, scattering, and continuum effects is discussed. Finally, prospects for improved measures of black hole spin and understanding the spin history of supermassive black holes in the context of black hole galaxy coevolution are presented. The best data and most rigorous results strongly suggest that relativistic X-ray disk lines can drive new explorations of General Relativity and disk physics in the future.

[]

https://arxiv.org/pdf/0705.0540.pdf

1994ApJ...432L..95H

A Model for the X-Ray and Ultraviolet Emission from Seyfert Galaxies and Galactic Black Holes

1994-01-01

['accretion disks', 'galaxies active', 'models', 'black hole physics', 'atoms', 'plasmas', 'galaxies seyfert', 'astronomy uv', 'astronomy uv', 'astronomy x rays', 'astronomy x rays', '-', 'atoms', 'gravitation', 'lightcurve', 'stars luminosity function;mass function', 'size determination', '-', 'accretion', 'accretion disks', 'plasmas', 'radiation', 'galaxies seyfert', 'astronomy x rays', 'astrophysics']

[]

We propose that the X-ray emission from radio-quiet active galactic nuclei and galactic black holes is due to Comptonization of soft thermal photons emitted by the underlying accretion disk in localized structures (blobs). The power per unit area produced by the blobs, impinging on the disk, can easily dominate the radiation internally produced by the disk. In this case the electron temperature and the high-energy spectrum can be determined in a similar way to that used in the previously studied homogeneous model (Haardt &amp; Maraschi 1991). However, in the present model, (a) the emitted spectrum is largely independent of the fraction of gravitational power dissipated in the blobs; (b) the X-ray spectrum can be harder depending on a form factor of the blobs; (c) the UV (or soft X- ray for galactic objects) luminosity that is not intercepted by the blobs can be larger than the X-ray luminosity. In the framework of a simplified accretion disk α<SUB>OMEGA</SUB> dynamo model, we make order-of-magnitude estimates of the number of active blobs, their size, their luminosity, and hence their compactness, finding values in agreement with what is observed. The expected UV to X-ray spectra and correlations of X-ray and UV light curves are discussed.

[]

https://arxiv.org/pdf/astro-ph/9405059.pdf

2006ApJ...649..616P

Probing the Coevolution of Supermassive Black Holes and Galaxies Using Gravitationally Lensed Quasar Hosts

2006-01-01

['black hole physics', 'galaxies bulges', 'galaxies evolution', 'galaxies fundamental parameters', 'galaxies structure', 'gravitational lensing', 'galaxies quasars', 'astrophysics']

[]

In the present-day universe, supermassive black hole masses (M<SUB>BH</SUB>) appear to be strongly correlated with their galaxy's bulge luminosity, among other properties. In this study we explore the analogous relationship between M<SUB>BH</SUB>, derived using the virial method, and the stellar R-band bulge luminosity (L<SUB>R</SUB>) or stellar bulge mass (M<SUB>*</SUB>) at epochs of 1&lt;~z&lt;~4.5, using a sample of 31 gravitationally lensed AGNs and 20 nonlensed AGNs. At redshifts z&gt;1.7 (10-12 Gyr ago), we find that the observed M<SUB>BH</SUB>-L<SUB>R</SUB> relation is nearly the same (to within ~0.3 mag) as it is today. When the observed L<SUB>R</SUB> are corrected for luminosity evolution, this means that the black holes grew in mass faster than their hosts, with the M<SUB>BH</SUB>/M<SUB>*</SUB> mass ratio being a factor of &gt;~4<SUP>+2</SUP><SUB>-1</SUB> times larger at z&gt;1.7 than it is today. By the redshift range 1&lt;~z&lt;~1.7 (8-10 Gyr ago), the M<SUB>BH</SUB>/M<SUB>*</SUB> ratio is at most 2 times higher than today, but it may be consistent with no evolution. Combining the results, we conclude that the ratio M<SUB>BH</SUB>/M<SUB>*</SUB> rises with look-back time, although it may saturate at ~6 times the local value. Scenarios in which moderately luminous quasar hosts at z&gt;~1.7 were fully formed bulges that passively faded to the present epoch are ruled out. <P />Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

[]

https://arxiv.org/pdf/astro-ph/0603248.pdf

1998MNRAS.300..817H

High-redshift galaxies, their active nuclei and central black holes

1998-01-01

['black hole physics', 'galaxies formation', 'galaxies nuclei', 'galaxies quasars', 'astrophysics']

[]

We demonstrate that the luminosity function of the recently detected population of actively star-forming galaxies at redshift z=3 and the B-band luminosity function of quasi-stellar objects (QSOs) at the same redshift can both be matched with the mass function of dark matter haloes predicted by standard variants of hierarchical cosmogonies for lifetimes of optically bright QSOs anywhere in the range 10^6 to 10^8yr. There is a strong correlation between the lifetime and the required degree of non-linearity in the relation between black hole and halo mass. We suggest that the mass of supermassive black holes may be limited by the back-reaction of the emitted energy on the accretion flow in a self-gravitating disc. This would imply a relation of black hole to halo mass of the form M_bh~v^5_halo~M^5/3_halo and a typical duration of the optically bright QSO phase of a few times 10^7yr. The high integrated mass density of black holes inferred from recent black hole mass estimates in nearby galaxies may indicate that the overall efficiency of supermassive black holes for producing blue light is smaller than previously assumed. We discuss three possible accretion modes with low optical emission efficiency: (i) accretion at far above the Eddington rate, (ii) accretion obscured by dust, and (iii) accretion below the critical rate leading to an advection-dominated accretion flow lasting for a Hubble time. We further argue that accretion with low optical efficiency might be closely related to the origin of the hard X-ray background and that the ionizing background might be progressively dominated by stars rather than QSOs at higher redshift.

[]

https://arxiv.org/pdf/astro-ph/9712259.pdf

2008CQGra..25i5014K

Fermions tunnelling from black holes

2008-01-01

['-']

[]

We investigate the tunnelling of spin-1/2 particles through event horizons. We first apply the tunnelling method to Rindler spacetime and obtain the Unruh temperature. We then apply fermion tunnelling to a general non-rotating black hole metric and show that the Hawking temperature is recovered.

[]

https://arxiv.org/pdf/0710.0612.pdf

2019JHEP...10..206B

Black hole binary dynamics from the double copy and effective theory

2019-01-01

['black hole physics', '-', '-', 'scattering', '-', '-', '-']

[]

We describe a systematic framework for computing the conservative potential of a compact binary system using modern tools from scattering amplitudes and effective field theory. Our approach combines methods for integration and matching adapted from effective field theory, generalized unitarity, and the double-copy construction, which relates gravity integrands to simpler gauge-theory expressions. With these methods we derive the third post-Minkowskian correction to the conservative two-body Hamiltonian for spinless black holes. We describe in some detail various checks of our integration methods and the resulting Hamiltonian.

[]

https://arxiv.org/pdf/1908.01493.pdf

1994PhRvD..50.3961K

Geometrodynamics of Schwarzschild black holes

1994-01-01

['-', '-', '-', '-', '-', 'black hole physics', '-']

[]

The curvature coordinates T, R of a Schwarzschild spacetime are turned into canonical coordinates T(r), ssR(r) on the phase space of spherically symmetric black holes. The entire dynamical content of the Hamiltonian theory is reduced to the constraints requiring that the momenta P<SUB>T</SUB>(r), P<SUB>ssR</SUB>(r) vanish. What remains is a conjugate pair of canonical variables m and p whose values are the same on every embedding. The coordinate m is the Schwarzschild mass and the momentum p the difference of parametrization times at right and left infinities. The Dirac constraint quantization in the new representation leads to the state functional Ψ(mT,ssR]=Ψ(m) which describes an unchanging superposition of black holes with different masses. The new canonical variables may be employed in the study of collapsing matter systems.

[]

https://arxiv.org/pdf/gr-qc/9403003.pdf

2003PThPh.110..701K

A Master Equation for Gravitational Perturbations of Maximally Symmetric Black Holes in Higher Dimensions

2003-01-01

['-', '-']

[]

We show that in four or more spacetime dimensions, the Einstein equations for gravitational perturbations of maximally symmetric vacuum black holes can be reduced to a single second-order wave equation in a two-dimensional static spacetime, irrespective of the mode of perturbations. Our starting point is the gauge-invariant formalism for perturbations in an arbitrary number of dimensions developed by the present authors, and the variable for the final second-order master equation is given by a simple combination of gauge-invariant variables in this formalism. Our formulation applies to the case of non-vanishing as well as vanishing cosmological constant Λ. The sign of the sectional curvature k of each spatial section of equipotential surfaces is also kept general. In the four-dimensional Schwarzschild background with Λ = 0 and k = 1, the master equation for a scalar perturbation is identical to the Zerilli equation for the polar mode and the master equation for a vector perturbation is identical to the Regge-Wheeler equation for the axial mode. Furthermore, in the four-dimensional Schwarzschild-anti-de Sitter background with Λ &lt; 0 and k = 0,1, our equation coincides with those recently derived by Cardoso and Lemos. As a simple application, we prove the perturbative stability and uniqueness of four-dimensional non-extremal spherically symmetric black holes for any Λ. We also point out that there exists no simple relation between scalar-type and vector-type perturbations in higher dimensions, unlike in four dimension. Although in the present paper we treat only the case in which the horizon geometry is maximally symmetric, the final master equations are valid even when the horizon geometry is described by a generic Einstein manifold, if we employ an appropriate reinterpretation of the curvature k and the eigenvalues for harmonic tensors.

[]

https://arxiv.org/pdf/hep-th/0305147.pdf

2013PhRvD..88j1502A

Reentrant phase transitions in rotating anti-de Sitter black holes

2013-01-01

['-', '-', '-', '-', '-', 'thermodynamics', '-', '-']

[]

We study the thermodynamics of higher-dimensional singly spinning asymptotically AdS black holes in the canonical (fixed J) ensemble of extended phase space, where the cosmological constant is treated as pressure and the corresponding conjugate quantity is interpreted as thermodynamic volume. Along with the usual small/large black hole phase transition, we find a new phenomenon of reentrant phase transitions for all d≥6 dimensions, in which a monotonic variation of the temperature yields two phase transitions from large to small and back to large black holes. This situation is similar to that seen in multicomponent liquids.

[]

https://arxiv.org/pdf/1306.5756.pdf

2017PhRvD..96l3523A

Merger rate of primordial black-hole binaries

2017-01-01

['-', '-', '-']

[]

Primordial black holes (PBHs) have long been a candidate for the elusive dark matter (DM), and remain poorly constrained in the ∼20 - 100 M<SUB>⊙</SUB> mass range. PBH binaries were recently suggested as the possible source of LIGO's first detections. In this paper, we thoroughly revisit existing estimates of the merger rate of PBH binaries. We compute the probability distribution of orbital parameters for PBH binaries formed in the early Universe, accounting for tidal torquing by all other PBHs, as well as standard large-scale adiabatic perturbations. We then check whether the orbital parameters of PBH binaries formed in the early Universe can be significantly affected between formation and merger. Our analytic estimates indicate that the tidal field of halos and interactions with other PBHs, as well as dynamical friction by unbound standard DM particles, do not do significant work on nor torque PBH binaries. We estimate the torque due to baryon accretion to be much weaker than previous calculations, albeit possibly large enough to significantly affect the eccentricity of typical PBH binaries. We also revisit the PBH-binary merger rate resulting from gravitational capture in present-day halos, accounting for Poisson fluctuations. If binaries formed in the early Universe survive to the present time, as suggested by our analytic estimates, they dominate the total PBH merger rate. Moreover, this merger rate would be orders of magnitude larger than LIGO's current upper limits if PBHs make a significant fraction of the dark matter. As a consequence, LIGO would constrain ∼10 - 300 M<SUB>⊙</SUB> PBHs to constitute no more than ∼1 % of the dark matter. To make this conclusion fully robust, though, numerical study of several complex astrophysical processes—such as the formation of the first PBH halos and how they may affect PBH binaries, as well as the accretion of gas onto an extremely eccentric binary—is needed.

[]

https://arxiv.org/pdf/1709.06576.pdf

2006ApJ...646...49R

A Compact Supermassive Binary Black Hole System

2006-01-01

['galaxies active', 'galaxies', 'astronomy radio', 'astronomy radio', 'astrophysics']

[]

We report on the discovery of a supermassive binary black hole system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the closest black hole pair yet found by more than 2 orders of magnitude. These results are based on recent multifrequency observations using the Very Long Baseline Array (VLBA), which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity systems with a combined mass of the two black holes of ~1.5×10<SUP>8</SUP> M<SUB>solar</SUB>. The two nuclei appear stationary, while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close binary black holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting system are also presented.

[]

https://arxiv.org/pdf/astro-ph/0604042.pdf

1994CQGra..11..621S

Black hole evaporation without information loss

1994-01-01

['-', '-']

[]

An approach to black hole quantization is proposed wherein it is assumed that quantum coherence is preserved. A consequence of this is that the Penrose diagram describing gravitational collapse will show the same topological structure as flat Minkowski space. After giving our motivations for such a quantization procedure we formulate the background field approximation, in which particles are divided into "hard" particles and "soft" particles. The background space-time metric depends both on the in-states and on the out-states. We present some model calculations and extensive discussions. In particular, we show, in the context of a toy model, that the $S$-matrix describing soft particles in the hard particle background of a collapsing star is unitary, nevertheless, the spectrum of particles is shown to be approximately thermal. We also conclude that there is an important topological constraint on functional integrals.

[]

https://arxiv.org/pdf/gr-qc/9310006.pdf

2016A&A...587A..61C

BlackCAT: A catalogue of stellar-mass black holes in X-ray transients

2016-01-01

['astronomy x rays', 'stars black holes', 'catalogs', '-', '-']

[]

<BR /> Aims: During the last ~50 years, the population of black hole candidates in X-ray binaries has increased considerably, with 59 Galactic objects being detected in transient low-mass X-ray binaries, as well as a few in persistent systems (including ~5 extragalactic binaries). <BR /> Methods: We collect near-infrared, optical, and X-ray information spread over hundreds of references to study the population of black holes in X-ray transients as a whole. <BR /> Results: We present the most updated catalogue of black hole transients. This contains X-ray, optical, and near-infrared observations, together with their astrometric and dynamical properties. The catalogue provides new and useful information in both statistical and observational parameters and provides a thorough and complete overview of the black hole population in the Milky Way. Analysing the distances and spatial distribution of the observed systems, we estimate a total population of ~1300 Galactic black hole transients. This means that we have only discovered less than ~5% of the total Galactic distribution. <P />The complete version of this catalogue will be continuously updated at <A href="https://www.astro.puc.cl/BlackCAT">https://www.astro.puc.cl/BlackCAT</A> and in the Virtual Observatory, including finding charts and data in other wavelengths.Tables A.1 to A.4 are also available in electronic form at the CDS via anonymous ftp to (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A61">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A61</A>

[]

https://arxiv.org/pdf/1510.08869.pdf

1993PhRvL..70.3684J

Black hole entropy and higher curvature interactions.

1993-01-01

['black hole physics', 'thermodynamics', 'theory', 'quantum theory', 'thermodynamics', 'scattering', '-', 'gravitation', '-', 'black hole physics', '-', '-', '-', '-', '-', 'thermodynamics', 'black hole physics', '-', '-']

[]

A general formula for the entropy of stationary black holes in Lovelock higher curvature gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.

[]

https://arxiv.org/pdf/hep-th/9305016.pdf

2004CQGra..21.5233D

Black-hole entropy from quantum geometry

2004-01-01

['-', '-']

[]

Quantum geometry (the modern loop quantum gravity involving graphs and spin-networks instead of the loops) provides microscopic degrees of freedom that account for black-hole entropy. However, the procedure for state counting used in the literature contains an error and the number of the relevant horizon states is underestimated. In our paper a correct method of counting is presented. Our results lead to a revision of the literature of the subject. It turns out that the contribution of spins greater than 1/2 to the entropy is not negligible. Hence, the value of the Barbero Immirzi parameter involved in the spectra of all the geometric and physical operators in this theory is different than previously derived. Also, the conjectured relation between quantum geometry and the black-hole quasi-normal modes should be understood again.

[]

https://arxiv.org/pdf/gr-qc/0407051.pdf

1996NuPhB.475..164K

Entropy of near-extremal black p-branes

1996-01-01

['-']

[]

We carry out a thorough survey of entropy for a large class of p-branes in various dimensions. We find that the Bekenstein-Hawking entropy may be given a simple world volume interpretation only for the non-dilatonic p-branes, those with the dilaton constant throughout spacetime. The entropy of extremal non-dilatonic p-branes is non-vanishing only for solutions preserving {1}/{8} of the original supersymmetries. Upon toroidal compactification these reduce to dyonic black holes in 4 and 5 dimensions. For the self-dual string in 6 dimensions, which preserves {1}/{4} of the original supersymmetries, the near-extremal entropy is found to agree with a world sheet calculation, in support of the existing literature. The remaining 3 interesting cases preserve {1}/{2} of the original supersymmetries. These are the self-dual 3-brave in 10 dimensions, and the 2- and 5-braves in 11 dimensions. For all of them the scaling of the near-extremal Bekenstein-Hawking entropy with the Hawking temperature is in agreement with a statistical description in terms of free massless fields on the world volume.

[]

https://arxiv.org/pdf/hep-th/9604089.pdf

2009PhRvL.102p1101S

Gravitational-Wave Background as a Probe of the Primordial Black-Hole Abundance

2009-01-01

['-', '-', '-', '-', 'waves', '-', 'background', 'cosmology miscellaneous', 'astrophysics', '-', '-']

[]

The formation of a significant number of black holes (PBHs) is realized if and only if primordial density fluctuations have a large amplitude, which means that tensor perturbations generated from these scalar perturbations as a second-order effect are also large and comparable to the observational data. We show that pulsar timing data essentially rule out PBHs with 10<SUP>2</SUP>-10<SUP>4</SUP>M<SUB>⊙</SUB>, which were previously considered as a candidate of intermediate-mass black holes, and that PBHs with a mass range of 10<SUP>20</SUP> to 10<SUP>26</SUP>g, which serves as a candidate of dark matter, may be probed by future space-based laser interferometers and atomic interferometers.

[]

https://arxiv.org/pdf/0812.4339.pdf

2003Natur.422..871U

First-generation black-hole-forming supernovae and the metal abundance pattern of a very iron-poor star

2003-01-01

['astrophysics']

[]

It has been proposed theoretically that the first generation of stars in the Universe (population III) would be as massive as 100 solar masses (100M<SUB>⊙</SUB>), because of inefficient cooling of the precursor gas clouds. Recently, the most iron-deficient (but still carbon-rich) low-mass star-HE0107-5240-was discovered. If this is a population III star that gained its metals (elements heavier than helium) after its formation, it would challenge the theoretical picture of the formation of the first stars. Here we report that the patterns of elemental abundance in HE0107-5240 (and other extremely metal-poor stars) are in good accord with the nucleosynthesis that occurs in stars with masses of 20-130M<SUB>⊙</SUB> when they become supernovae if, during the explosions, the ejecta undergo substantial mixing and fallback to form massive black holes. Such supernovae have been observed. The abundance patterns are not, however, consistent with enrichment by supernovae from stars in the range 130-300M<SUB>⊙</SUB>. We accordingly infer that the first-generation supernovae came mostly from explosions of ~20-130M<SUB>⊙</SUB> stars; some of these produced iron-poor but carbon- and oxygen-rich ejecta. Low-mass second-generation stars, like HE0107-5240, could form because the carbon and oxygen provided pathways for the gas to cool.

[]

https://arxiv.org/pdf/astro-ph/0301315.pdf

2001MNRAS.320L..30M

Black hole demographics from the M<SUB>•</SUB>-σ relation

2001-01-01

['galaxies active', 'galaxies fundamental parameters', 'galaxies kinematics and dynamics', 'astrophysics']

[]

We analyse a sample of 32 galaxies for which a dynamical estimate of the mass of the hot stellar component, M<SUB>bulge</SUB>, is available. For each of these galaxies, we calculate the mass of the central black hole, M<SUB>•</SUB>, using the tight empirical correlation between M<SUB>•</SUB> and bulge stellar velocity dispersion. The frequency function N[log(M<SUB>•</SUB>M<SUB>bulge</SUB>)] is reasonably well described as a Gaussian with &lt;log(M<SUB>•</SUB>M<SUB>bulge</SUB>)&gt;~-2.90 and standard deviation ~0.45 the implied mean ratio of black hole mass to bulge mass is a factor of ~5 smaller than generally quoted in the literature. We present marginal evidence for a lower, average black hole mass fraction in more massive galaxies. The total mass density in black holes in the local Universe is estimated to be ~ 5×10<SUP>5</SUP>M<SUB>solar</SUB>Mpc<SUP>-3</SUP>, consistent with that inferred from high-redshift (z~2) active galactic nuclei.

[]

https://arxiv.org/pdf/astro-ph/0009076.pdf

2016RvMP...88a5002H

Jerusalem lectures on black holes and quantum information

2016-01-01

['-', '-', '-']

[]

These lectures give an introduction to the quantum physics of black holes, including recent developments based on quantum information theory such as the firewall paradox and its various cousins. An introduction is also given to holography and the anti-de Sitter/conformal field theory (AdS/CFT) correspondence, focusing on those aspects which are relevant for the black hole information problem.

[]

https://arxiv.org/pdf/1409.1231.pdf

2003ApJ...583..616J

Gravitational Waves Probe the Coalescence Rate of Massive Black Hole Binaries

2003-01-01

['black hole physics', 'galaxies interactions', 'gravitational waves', 'astrophysics']

[]

We calculate the expected nHz-μHz gravitational wave (GW) spectrum from coalescing massive black hole (MBH) binaries resulting from mergers of their host galaxies. We consider detection of this spectrum by precision pulsar timing and a future pulsar timing array. The spectrum depends on the merger rate of massive galaxies, the demographics of MBHs at low and high redshift, and the dynamics of MBH binaries. We apply recent theoretical and observational work on all of these fronts. The spectrum has a characteristic strain h<SUB>c</SUB>(f)~10<SUP>-15</SUP>(f/yr<SUP>-1</SUP>)<SUP>-2/3</SUP>, just below the detection limit from recent analysis of precision pulsar timing measurements. However, the amplitude of the spectrum is still very uncertain owing to approximations in the theoretical formulation of the model, to our lack of knowledge of the merger rate and MBH population at high redshift, and to the dynamical problem of removing enough angular momentum from the MBH binary to reach a GW-dominated regime.

[]

https://arxiv.org/pdf/astro-ph/0210148.pdf

2005ApJ...628..368O

Supercritical Accretion Flows around Black Holes: Two-dimensional, Radiation Pressure-dominated Disks with Photon Trapping

2005-01-01

['accretion', 'accretion disks', 'black hole physics', 'hydrodynamics', 'methods numerical', 'radiative transfer', 'astrophysics']

[]

The quasi-steady structure of supercritical accretion flows around a black hole is studied based on two-dimensional radiation-hydrodynamic (2D-RHD) simulations. The supercritical flow is composed of two parts: the disk region and the outflow regions above and below the disk. Within the disk region the circular motion and the patchy density structure are observed, which is caused by Kelvin-Helmholtz instability and probably by convection. The mass accretion rate decreases inward, roughly in proportion to the radius, and the remaining part of the disk material leaves the disk to form the outflow because of the strong radiation pressure force. We confirm that photon trapping plays an important role within the disk. Thus, matter can fall onto the black hole at a rate exceeding the Eddington rate. The emission is highly anisotropic and moderately collimated so that the apparent luminosity can exceed the Eddington luminosity by a factor of a few in the face-on view. The mass accretion rate onto the black hole increases with the absorption opacity (metallicity) of the accreting matter. This implies that the black hole tends to grow faster in metal-rich regions, such as in starburst galaxies or star-forming regions.

[]

https://arxiv.org/pdf/astro-ph/0504168.pdf

2003MNRAS.345..657K

Black hole winds

2003-01-01

['accretion', 'accretion disks', 'black hole physics', 'galaxies quasars', 'astronomy x rays', 'astronomy x rays', 'astrophysics']

[]

We show that black holes accreting at or above the Eddington rate probably produce winds that are optically thick in the continuum, whether in quasars or in X-ray binaries. The photospheric radius and outflow speed are proportional to and respectively, where is the mass outflow rate. The momentum outflow rate is always of the order of L<SUB>Edd</SUB>/c. Blackbody emission from these winds may provide the big blue bump in some quasars and active galactic nuclei, as well as ultrasoft X-ray components in ultraluminous X-ray sources.

[]

https://arxiv.org/pdf/astro-ph/0305541.pdf

1996ApJ...457..834T

The Neutron Star and Black Hole Initial Mass Function

1996-01-01

['black hole physics', '-', 'stars luminosity function;mass function', 'stars luminosity function;mass function', '-', '-', 'astrophysics']

[]

Using recently calculated models for massive stellar evolution and supernovae coupled to a model for Galactic chemical evolution, neutron star and black hole birth functions (number of neutron stars and black holes as a function of their mass) are determined for the Milky Way galaxy. For those stars that explode as Type II supernovae, the models give birth functions that are bimodal with peaks at 1.27 and 1.76 M<SUB>sun</SUB> and average masses within those peaks of 1.28 and 1.73 M<SUB>0</SUB>. For these stars that explode as Type Ib there is a narrower spread of remnant masses, the average being 1.32 M<SUB>sun</SUB>, and less evidence for bimodality. These values will be increased, especially in the more massive Type II supernovae, if significant accretion continues during the initial launching of the shock, and the number of heavier neutron stars could be depleted by black hole formation. The principal reason for the dichotomy in remnant masses for Type II is the difference in the presupernova structure of stars above and below 19 M<SUB>sun</SUB>, the mass separating stars that burn carbon convectively from those that produce less carbon and burn radiatively. The Type Ib's and the lower mass group of the Type II's compare favorably with measured neutron star masses, and in particular to the Thorsett et al. (1993) determination of the average neutron star mass in 17 systems 1.35±0.27 M<SUB>sun</SUB>. Variations in the exponent of a Salpeter initial mass function are shown not to affect the locations of the two peaks in the distribution function, but do affect their relative amplitudes. Sources of uncertainty, in particular placement of the mass cut and sensitivity to the explosion energy, are discussed, and estimates of the total number of neutron stars and black holes in the Galaxy are given. Accretion-induced collapse should give a unique gravitational mass of 1.27 M<SUB>sun</SUB>, although this could increase if accretion onto the newly formed star continues. A similar mass will typify stars in the 8-11 M<SUB>sun</SUB> range (e.g., the Crab pulsar). The lightest neutron star produced is 1.15 M<SUB>sun</SUB> for the Type II models and 1.22 M<SUB>sun</SUB> for the Type Ib models. Altogether there are about 10<SUP>9</SUP> neutron stars in our Galaxy and a comparable number of black holes.

[]

https://arxiv.org/pdf/astro-ph/9510136.pdf

2005ApJS..157..335L

Multitemperature Blackbody Spectrum of a Thin Accretion Disk around a Kerr Black Hole: Model Computations and Comparison with Observations

2005-01-01

['accretion', 'accretion disks', 'black hole physics', 'radiation', 'astronomy x rays', 'astrophysics']

[]

We use a ray-tracing technique to compute the observed spectrum of a thin accretion disk around a Kerr black hole. We include all relativistic effects such as frame-dragging, Doppler boost, gravitational redshift, and bending of light by the gravity of the black hole. We also include self-irradiation of the disk as a result of light deflection. Assuming that the disk emission is locally blackbody, we show how the observed spectrum depends on the spin of the black hole, the inclination of the disk, and the torque at the inner edge of the disk. We find that the effect of a nonzero torque on the spectrum can, to a good approximation, be absorbed into a zero-torque model by adjusting the mass accretion rate and the normalization. We describe a computer model, called KERRBB, which we have developed for fitting the spectra of black hole X-ray binaries. Using KERRBB within the X-ray data reduction package XSPEC, and assuming a spectral hardening factor f<SUB>col</SUB>=1.7, we analyze the spectra of three black hole X-ray binaries: 4U 1543-47, XTE J1550-564, and GRO J1655-40. We estimate the spin parameters of the black holes in 4U 1543-47 and GRO J1655-40 to be a/M~0.6 and ~0.6-0.7, respectively. If f<SUB>col</SUB>~1.5-1.6, as in a recent study, then we find a/M~0.7-0.8 and ~0.8-0.9, respectively. These estimates are subject to additional uncertainties in the assumed black hole masses, distances, and disk inclinations.

[]

https://arxiv.org/pdf/astro-ph/0411583.pdf

2014A&ARv..22...72U

X-ray reverberation around accreting black holes

2014-01-01

['accretion', 'accretion disks', 'black hole physics', 'galaxies active', 'galaxies seyfert', 'astronomy x rays', '-', '-', '-']

[]

Luminous accreting stellar mass and supermassive black holes produce power-law continuum X-ray emission from a compact central corona. Reverberation time lags occur due to light travel time delays between changes in the direct coronal emission and corresponding variations in its reflection from the accretion flow. Reverberation is detectable using light curves made in different X-ray energy bands, since the direct and reflected components have different spectral shapes. Larger, lower frequency, lags are also seen and are identified with propagation of fluctuations through the accretion flow and associated corona. We review the evidence for X-ray reverberation in active galactic nuclei and black hole X-ray binaries, showing how it can be best measured and how it may be modelled. The timescales and energy dependence of the high-frequency reverberation lags show that much of the signal is originating from very close to the black hole in some objects, within a few gravitational radii of the event horizon. We consider how these signals can be studied in the future to carry out X-ray reverberation mapping of the regions closest to black holes.

[]

https://arxiv.org/pdf/1405.6575.pdf

2018MNRAS.479.4056W

Supermassive black holes and their feedback effects in the IllustrisTNG simulation

2018-01-01

['methods numerical', 'galaxies active', 'galaxies evolution', 'galaxies general', 'galaxies seyfert', '-', '-']

[]

We study the population of supermassive black holes (SMBHs) and their effects on massive central galaxies in the IllustrisTNG cosmological hydrodynamical simulations of galaxy formation. The employed model for SMBH growth and feedback assumes a two-mode scenario in which the feedback from active galactic nuclei occurs through a kinetic, comparatively efficient mode at low accretion rates relative to the Eddington limit, and in the form of a thermal, less efficient mode at high accretion rates. We show that the quenching of massive central galaxies happens coincidently with kinetic-mode feedback, consistent with the notion that active supermassive black holes cause the low specific star formation rates observed in massive galaxies. However, major galaxy mergers are not responsible for initiating most of the quenching events in our model. Up to black hole masses of about 10^{8.5} M_{⊙}, the dominant growth channel for SMBHs is in the thermal mode. Higher mass black holes stay mainly in the kinetic mode and gas accretion is self-regulated via their feedback, which causes their Eddington ratios to drop, with SMBH mergers becoming the main channel for residual mass growth. As a consequence, the quasar luminosity function is dominated by rapidly accreting, moderately massive black holes in the thermal mode. We show that the associated growth history of SMBHs produces a low-redshift quasar luminosity function and a redshift zero black hole mass - stellar bulge mass relation is in good agreement with observations, whereas the simulation tends to overpredict the high-redshift quasar luminosity function.

[]

https://arxiv.org/pdf/1710.04659.pdf

2016NatPh..12..959S

Observation of quantum Hawking radiation and its entanglement in an analogue black hole

2016-01-01

['-']

[]

We observe spontaneous Hawking radiation, stimulated by quantum vacuum fluctuations, emanating from an analogue black hole in an atomic Bose–Einstein condensate. Correlations are observed between the Hawking particles outside the black hole and the partner particles inside. These correlations indicate an approximately thermal distribution of Hawking radiation. We find that the high-energy pairs are entangled, while the low-energy pairs are not, within the reasonable assumption that excitations with different frequencies are not correlated. The entanglement verifies the quantum nature of the Hawking radiation. The results are consistent with a driven oscillation experiment and a numerical simulation.

[]

https://arxiv.org/pdf/1510.00621.pdf

2019Sci...365..664D

Relativistic redshift of the star S0-2 orbiting the Galactic Center supermassive black hole

2019-01-01

['-', '-', '-']

[]

The general theory of relativity predicts that a star passing close to a supermassive black hole should exhibit a relativistic redshift. In this study, we used observations of the Galactic Center star S0-2 to test this prediction. We combined existing spectroscopic and astrometric measurements from 1995-2017, which cover S0-2’s 16-year orbit, with measurements from March to September 2018, which cover three events during S0-2’s closest approach to the black hole. We detected a combination of special relativistic and gravitational redshift, quantified using the redshift parameter ϒ. Our result, ϒ = 0.88 ± 0.17, is consistent with general relativity (ϒ = 1) and excludes a Newtonian model (ϒ = 0) with a statistical significance of 5σ.

[]

https://arxiv.org/pdf/1907.10731.pdf

1997PhRvD..55..861M

Black hole greybody factors and D-brane spectroscopy

1997-01-01

['-', '-', '-', '-', '-', '-', '-']

[]

Black holes do not Hawking-radiate strictly blackbody radiation due to well-known frequency-dependent greybody factors. These factors arise from frequency-dependent potential barriers outside the horizon which filter the initially blackbody spectrum emanating from the horizon. D-brane bound states, in a thermally excited state corresponding to near-extremal black holes, also do not emit blackbody radiation: The bound state radiation spectrum encodes the energy spectrum of its excitations. We study a near-extremal five-dimensional black hole. We show that in a wide variety of circumstances including both neutral and charged emission, the effect of the greybody filter is to transform the blackbody radiation spectrum precisely into the bound state radiation spectrum. Implications of this result for the information puzzle in the context of near-extremal black hole dynamics are discussed.

[]

https://arxiv.org/pdf/hep-th/9609026.pdf

2008ApJ...680..829R

Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates

2008-01-01

['black hole physics', 'cosmology cosmic microwave background', 'cosmology observations', 'cosmology theory', 'cosmology cosmological parameters', 'cosmology early universe', 'astrophysics', '-', '-']

[]

We investigate the effect of nonevaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the cosmic microwave background (CMB). Using the third-year WMAP data and COBE FIRAS data we improve existing upper limits on the abundance of PBHs with masses &gt;0.1 M<SUB>⊙</SUB> by several orders of magnitude. The new upper limits still allow PBHs to be important for the origin of supermassive black holes and ultraluminous X-ray sources. Fitting WMAP3 data with cosmological models that do not allow for nonstandard recombination histories, as produced by PBHs or other early energy sources, may lead to an underestimate of the best-fit values of the amplitude of linear density fluctuations (σ<SUB>8</SUB>) and the scalar spectral index (n<SUB>s</SUB>). Cosmological parameter estimates are affected because models with PBHs allow for larger values of the Thomson scattering optical depth, whose correlation with other parameters may not be correctly taken into account when PBHs are ignored. Values of τ<SUB>e</SUB> ~ 0.2, n<SUB>s</SUB> ~ 1, and σ<SUB>8</SUB> ~ 0.9 are allowed at 95% CF. This result may relieve recent tension between WMAP3 data and clusters data on the value of σ<SUB>8</SUB>. PBHs may increase the primordial molecular hydrogen abundance by up to 2 orders of magnitude, this promoting cooling and star formation. The suppression of galaxy formation due to X-ray heating is negligible for models consistent with the CMB data. Thus, the formation rate of the first galaxies and stars would be enhanced by a population of PBHs.

[]

https://arxiv.org/pdf/0709.0524.pdf

2004ApJ...604..632G

Formation of Massive Black Holes in Dense Star Clusters. I. Mass Segregation and Core Collapse

2004-01-01

['black hole physics', 'galaxies nuclei', 'galaxies starburst', 'galaxies star clusters', 'methods n body', 'stars kinematics and dynamics', 'astrophysics']

[]

We study the early dynamical evolution of young dense star clusters by using Monte Carlo simulations for systems with up to N=10<SUP>7</SUP> stars. Rapid mass segregation of massive main-sequence stars and the development of the Spitzer instability can drive these systems to core collapse in a small fraction of the initial half-mass relaxation time. If the core-collapse time is less than the lifetime of the massive stars, all stars in the collapsing core may then undergo a runaway collision process leading to the formation of a massive black hole. Here we study in detail the first step in this process, up to the occurrence of core collapse. We have performed about 100 simulations for clusters with a wide variety of initial conditions, varying systematically the cluster density profile, stellar initial mass function (IMF), and number of stars. We also considered the effects of initial mass segregation and stellar evolution mass loss. Our results show that, for clusters with a moderate initial central concentration and any realistic IMF, the ratio of core-collapse time to initial half-mass relaxation time is typically ~0.1, in agreement with the value previously found by direct N-body simulations for much smaller systems. Models with even higher central concentration initially, or with initial mass segregation (from star formation) have even shorter core collapse times. Remarkably, we find that, for all realistic initial conditions, the mass of the collapsing core is always close to ~10<SUP>-3</SUP> of the total cluster mass, very similar to the observed correlation between central black hole mass and total cluster mass in a variety of environments. We discuss the implications of our results for the formation of intermediate-mass black holes in globular clusters and super star clusters, ultraluminous X-ray sources, and seed black holes in proto-galactic nuclei.

[]

https://arxiv.org/pdf/astro-ph/0308449.pdf

1999ApJ...521L..95P

Keplerian Motion of Broad-Line Region Gas as Evidence for Supermassive Black Holes in Active Galactic Nuclei

1999-01-01

['galaxies active', 'galaxies', 'galaxies seyfert', 'galaxies quasars', 'galaxies active', 'galaxies', 'galaxies seyfert', 'galaxies quasars', 'astrophysics']

[]

Emission-line variability data on NGC 5548 argue strongly for the existence of a mass of order 7×10<SUP>7</SUP> M<SUB>solar</SUB> within the inner few light-days of the nucleus in the Seyfert 1 galaxy NGC 5548. The time-delayed response of the emission lines to continuum variations is used to infer the size of the line-emitting region, and these determinations are combined with measurements of the Doppler widths of the variable line components to estimate a virial mass. The data for several different emission lines spanning an order of magnitude in distance from the central source show the expected V~r<SUP>-1/2</SUP> correlation and are consistent with a single value for the mass.

[]

https://arxiv.org/pdf/astro-ph/9905382.pdf

1992NuPhB.383..395R

Supersymmetric, cold and lukewarm black holes in cosmological Einstein-Maxwell theory

1992-01-01

['-']

[]

In asymptotically flat (AF) space, the extreme Reissner-Nordstrøm (RN) black hole is distinguished by its coldness (vanishing Hawking temperature) and its supersymmetry. We examine RN solutions to Einstein-Maxwell theory with a cosmological constant Λ, classifying the cold black holes and, for positive Λ, the ``lukewarm'' black holes at the same temperature as the de Sitter thermal background. For negative Λ, we classify the supersymmetric solutions within the context of N = 2 gauged supergravity. One finds supersymmetric analogues of AF-space extreme RN black holes, which for nonzero Λ differ from the cold black holes. In addition, these is an exotic class of supersymmetric solutions which cannot be continued to asymptotically flat space, since the magnetic charge becomes infinite in that limit.

[]

https://arxiv.org/pdf/hep-th/9203018.pdf

2014MNRAS.442.2304H

Cosmological simulations of black hole growth: AGN luminosities and downsizing

2014-01-01

['methods numerical', 'galaxies active', 'galaxies evolution', 'galaxies quasars', 'galaxies quasars', 'galaxies statistics', '-']

[]

In this study, we present a detailed, statistical analysis of black hole growth and the evolution of active galactic nuclei (AGN) using cosmological hydrodynamic simulations run down to z = 0. The simulations self-consistently follow radiative cooling, star formation, metal enrichment, black hole growth and associated feedback processes from both Type II/Ia supernovae and AGN. We consider two simulation runs, one with a large comoving volume of (500 Mpc)<SUP>3</SUP> and one with a smaller volume of (68 Mpc)<SUP>3</SUP> but with a factor of almost 20 higher mass resolution. We compare the predicted statistical properties of AGN with results from large observational surveys. Consistently with previous results, our simulations can widely match observed black hole properties of the local Universe. Furthermore, our simulations can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low-luminosity and the high-luminosity end up to z = 3.0, only at z = 1.5-2.5, the low-luminosity end is overestimated by up to 1 dex. In addition, the smaller but higher resolution run is able to match the observational data of the low bolometric luminosity end at higher redshifts z = 3-4. We also perform a direct comparison with the observed soft and hard X-ray luminosity functions of AGN, including an empirical correction for a torus-level obscuration, and find a similarly good agreement. These results nicely demonstrate that the observed `antihierarchical' trend in the AGN number density evolution (i.e. the number densities of luminous AGN peak at higher redshifts than those of faint AGN) is self-consistently predicted by our simulations. Implications of this downsizing behaviour on active black holes, their masses and Eddington ratios are discussed. Overall, the downsizing behaviour in the AGN number density as a function of redshift can be mainly attributed to the evolution of the gas density in the resolved vicinity of a (massive) black hole (which is depleted with evolving time as a consequence of star formation and AGN feedback).

[]

https://arxiv.org/pdf/1308.0333.pdf

2013PhRvD..88h4051H

Threshold of primordial black hole formation

2013-01-01

['-', '-', '-', '-', 'black hole physics', 'cosmology dark matter', '-', '-', '-', '-']

[]

Based on a physical argument, we derive a new analytic formula for the amplitude of density perturbation at the threshold of primordial black hole formation in the Universe dominated by a perfect fluid with the equation of state p=wρc<SUP>2</SUP> for w≥0. The formula gives δ<SUB>Hc</SUB><SUP>UH</SUP>=sin⁡<SUP>2</SUP>[πw/(1+3w)] and δ∼<SUB>c</SUB>=[3(1+w)/(5+3w)]sin⁡<SUP>2</SUP>[πw/(1+3w)], where δ<SUB>Hc</SUB><SUP>UH</SUP> and δ∼<SUB>c</SUB> are the amplitude of the density perturbation at the horizon crossing time in the uniform Hubble slice and the amplitude measure used in numerical simulations, respectively, while the conventional one gives δ<SUB>Hc</SUB><SUP>UH</SUP>=w and δ∼<SUB>c</SUB>=3w(1+w)/(5+3w). Our formula shows a much better agreement with the result of recent numerical simulations both qualitatively and quantitatively than the conventional formula. For a radiation fluid, our formula gives δ<SUB>Hc</SUB><SUP>UH</SUP>=sin⁡<SUP>2</SUP>(3π/6)≃0.6203 and δ∼<SUB>c</SUB>=(2/3)sin⁡<SUP>2</SUP>(3π/6)≃0.4135. We also discuss the maximum amplitude and the cosmological implications of the present result.

[]

https://arxiv.org/pdf/1309.4201.pdf

2008ApJS..175..390H

A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies. II. Formation of Red Ellipticals

2008-01-01

['cosmology theory', 'galaxies active', 'galaxies evolution', 'galaxies quasars', 'astrophysics']

[]

We develop and test a model for the cosmological role of mergers in the formation and quenching of red, early-type galaxies. By combining theoretically well-constrained halo and subhalo mass functions as a function of redshift and environment with empirical halo occupation models, we predict the distribution of mergers as a function of redshift, environment, and physical galaxy properties. Making the simple Ansatz that star formation is quenched after a gas-rich, spheroid-forming major merger, we demonstrate that this naturally predicts the turnover in the efficiency of star formation and baryon fractions in galaxies at ~L<SUB>*</SUB> (without any parameters tuned to this value), as well as the observed mass functions and mass density of red galaxies as a function of redshift, the formation times of early-type galaxies as a function of mass, and the fraction of quenched galaxies as a function of galaxy and halo mass, environment, and redshift. Comparing our model to a variety of semianalytic models in which quenching is primarily driven by halo mass considerations or secular/disk instabilities, we demonstrate that our model makes unique and robust qualitative predictions for a number of observables, including the bivariate red fraction as a function of galaxy and halo mass, the density of passive galaxies at high redshifts, the emergence/evolution of the color-morphology-density relations at high redshift, and the fraction of disky/boxy (or cusp/core) spheroids as a function of mass. In each case, the observations favor a model in which some mechanism quenches future star formation after a major merger builds a massive spheroid. Models where quenching is dominated by a halo mass threshold fail to match the behavior of the bivariate red fractions, predict too low a density of passive galaxies at high redshift, and overpredict by an order of magnitude the mass of the transition from disky to boxy ellipticals. Models driven by secular disk instabilities also qualitatively disagree with the bivariate red fractions, fail to predict the observed evolution in the color-density relations, and predict order-of-magnitude incorrect distributions of kinematic types in early-type galaxies. We make specific predictions for how future observations, for example, quantifying the red fraction as a function of galaxy mass, halo mass, environment, or redshift, can break the degeneracies between a number of different assumptions adopted in present galaxy formation models. We discuss a variety of physical possibilities for this quenching and propose a mixed scenario in which traditional quenching in hot, quasi-static massive halos is supplemented by the strong shocks and feedback energy input associated with a major merger (e.g., tidal shocks, starburst-driven winds, and quasar feedback), which temporarily suppress cooling and establish the conditions of a dynamically hot halo in the central regions of the host, even in low-mass halos (below the traditional threshold for accretion shocks).

[]

https://arxiv.org/pdf/0706.1246.pdf

2014Galax...2...89A

Thermodynamics of Rotating Black Holes and Black Rings: Phase Transitions and Thermodynamic Volume

2014-01-01

['black hole physics', 'thermodynamics', '-', '-', '-', '-', '-', '-']

[]

In this review we summarize, expand, and set in context recent developments on the thermodynamics of black holes in extended phase space, where the cosmological constant is interpreted as thermodynamic pressure and treated as a thermodynamic variable in its own right. We specifically consider the thermodynamics of higher-dimensional rotating asymptotically flat and AdS black holes and black rings in a canonical (fixed angular momentum) ensemble. We plot the associated thermodynamic potential—the Gibbs free energy—and study its behavior to uncover possible thermodynamic phase transitions in these black hole spacetimes. We show that the multiply-rotating Kerr-AdS black holes exhibit a rich set of interesting thermodynamic phenomena analogous to the "every day thermodynamics" of simple substances, such as reentrant phase transitions of multicomponent liquids, multiple first-order solid/liquid/gas phase transitions, and liquid/gas phase transitions of the van der Waals type. Furthermore, the reentrant phase transitions also occur for multiply-spinning asymptotically flat Myers–Perry black holes. These phenomena do not require a variable cosmological constant, though they are more naturally understood in the context of the extended phase space. The thermodynamic volume, a quantity conjugate to the thermodynamic pressure, is studied for AdS black rings and demonstrated to satisfy the reverse isoperimetric inequality; this provides a first example of calculation confirming the validity of isoperimetric inequality conjecture for a black hole with non-spherical horizon topology. The equation of state P = P ( V , T ) is studied for various black holes both numerically and analytically—in the ultraspinning and slow rotation regimes.

[]

https://arxiv.org/pdf/1401.2586.pdf

2003PhRvL..90h1301D

Quasinormal Modes, the Area Spectrum, and Black Hole Entropy

2003-01-01

['-', '-', '-', '-', '-']

[]

The results of loop quantum gravity concerning geometric operators and black hole entropy are beset by an ambiguity labeled by the Immirzi parameter. We use a result from classical gravity concerning the quasinormal mode spectrum of a black hole to fix this parameter in a new way. As a result we arrive at the Bekenstein-Hawking expression of A/4l<SUP>2</SUP><SUB>P</SUB> for the entropy of a black hole and in addition see an indication that the appropriate gauge group of quantum gravity is SO(3) and not its covering group SU(2).

[]

https://arxiv.org/pdf/gr-qc/0211076.pdf

2014MNRAS.441.3444M

Red or blue? A potential kilonova imprint of the delay until black hole formation following a neutron star merger

2014-01-01

['accretion', 'accretion disks', 'dense matter', 'gravitational waves', 'hydrodynamics', 'neutrinos', 'nuclear reactions;nucleosynthesis;abundances', 'nuclear reactions;nucleosynthesis;abundances', 'nuclear reactions;nucleosynthesis;abundances', '-', '-', '-', 'nuclear reactions;nucleosynthesis;abundances']

[]

Mergers of binary neutron stars usually result in the formation of a hypermassive neutron star (HMNS). Whether and when this remnant collapses to a black hole (BH) depends primarily on the equation of state and on angular momentum transport processes, both of which are uncertain. Here, we show that the lifetime of the merger remnant may be directly imprinted in the radioactively powered kilonova emission following the merger. We employ axisymmetric, time-dependent hydrodynamic simulations of remnant accretion discs orbiting an HMNS of variable lifetime, and characterize the effect of this delay to BH formation on the disc wind ejecta. When BH formation is relatively prompt (≲100 ms), outflows from the disc are sufficiently neutron rich to form heavy r-process elements, resulting in ∼week-long emission with a spectral peak in the near-infrared (NIR), similar to that produced by the dynamical ejecta. In contrast, delayed BH formation allows neutrinos from the HMNS to raise the electron fraction in the polar direction to values such that potentially Lanthanide-free outflows are generated. The lower opacity would produce a brighter, bluer, and shorter-lived ∼ day-long emission (a `blue bump') prior to the late NIR peak from the dynamical ejecta and equatorial wind. This new diagnostic of BH formation should be useful for events with a signal to noise lower than that required for direct detection of gravitational waveform signatures.

[]

https://arxiv.org/pdf/1402.4803.pdf

2005PhRvL..95p1301C

General Nonextremal Rotating Black Holes in Minimal Five-Dimensional Gauged Supergravity

2005-01-01

['-', '-', '-', '-', '-', '-', '-', '-', '-', '-']

[]

We construct the general solution for nonextremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterized by four nontrivial parameters: namely, the mass, the charge, and the two independent rotation parameters. The metrics in general describe regular rotating black holes, providing the parameters lie in appropriate ranges so that naked singularities and closed timelike curves (CTCs) are avoided. We calculate the conserved energy, angular momenta, and charge for the solutions, and show how supersymmetric solutions arise in a Bogomol’nyi-Prasad-Sommerfield limit. These have naked CTCs in general, but for special choices of the parameters we obtain new regular supersymmetric black holes or smooth topological solitons.

[]

https://arxiv.org/pdf/hep-th/0506029.pdf

2000A&A...359..251C

Coupling of the X-ray and radio emission in the black hole candidate and compact jet source GX 339-4

2000-01-01

['-', 'gamma rays', 'astronomy radio', 'astronomy x rays', 'accretion', 'accretion disks', 'black hole physics', 'astrophysics']

[]

We report the results of a long-term campaign of radio, soft- and hard- X-ray observations of the galactic black hole candidate GX 339-4. In the Low-Hard X-ray state the system displays a strong 3-way linear correlation between soft- and hard-X-rays and radio emission, implying a coupling between the Comptonising corona and a radio-emitting compact jet. In this state the radio emission is linearly polarised at a level of around 2%, with an almost constant polarisation angle, indicative of a favored axis in this system probably related to the compact jet and/or black hole spin axis. In the Off X-ray state the radio emission declines with the X-ray emission to below detectable levels, suggesting that it is simply a lower-luminosity version of the Low-Hard state. In the High-Soft state both the hard-X-ray and radio emission are suppressed. We also note that the transitions from the Low-Hard state to the High-Soft state (and the reverse) are possibly associated with discrete ejection(s) of expanding relativistic plasma.

[]

https://arxiv.org/pdf/astro-ph/0003460.pdf

2015PhRvL.115e1101R

Binary Black Hole Mergers from Globular Clusters: Implications for Advanced LIGO

2015-01-01

['-', '-', 'waves', '-', '-', '-']

[]

The predicted rate of binary black hole mergers from galactic fields can vary over several orders of magnitude and is extremely sensitive to the assumptions of stellar evolution. But in dense stellar environments such as globular clusters, binary black holes form by well-understood gravitational interactions. In this Letter, we study the formation of black hole binaries in an extensive collection of realistic globular cluster models. By comparing these models to observed Milky Way and extragalactic globular clusters, we find that the mergers of dynamically formed binaries could be detected at a rate of ∼100 per year, potentially dominating the binary black hole merger rate. We also find that a majority of cluster-formed binaries are more massive than their field-formed counterparts, suggesting that Advanced LIGO could identify certain binaries as originating from dense stellar environments.

[]

https://arxiv.org/pdf/1505.00792.pdf

2004ARA&A..42..317F

GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems

2004-01-01

['astrophysics']

[]

GRS 1915+105 the first stellar-scale, highly relativistic jet source identified is a key system for our understanding of the disc-jet coupling in accreting black hole systems. Comprehending the coupling between inflow and outflow in this source not only is important for X-ray binary systems but has a broader relevance for studies of active galactic nuclei and gamma-ray bursts. In this paper, we present a detailed review of the observational properties of the system, as established in the decade since its discovery. We attempt to place it in context by a detailed comparison with other sources, and construct a simple model for the disc-jet coupling, which may be more widely applicable to accreting black hole systems.

[]

https://arxiv.org/pdf/astro-ph/0406483.pdf