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2019MNRAS.482...52S

Shadows of spherically symmetric black holes and naked singularities

2019-01-01

['accretion', 'accretion disks', 'black hole physics', 'gravitation', 'gravitational lensing', 'galaxy center', 'radiative transfer', '-', '-', '-']

[]

We compare shadows cast by Schwarzschild black holes with those produced by two classes of naked singularities that result from gravitational collapse of spherically symmetric matter. The latter models consist of an interior naked singularity space-time restricted to radii r ≤ R<SUB>b</SUB>, matched to Schwarzschild space-time outside the boundary radius R<SUB>b</SUB>. While a black hole always has a photon sphere and always casts a shadow, we find that the naked singularity models have photon spheres only if a certain parameter M<SUB>0</SUB> that characterizes these models satisfies M<SUB>0</SUB> ≥ 2/3, or equivalently, if R<SUB>b</SUB> ≤ 3M, where M is the total mass of the object. Such models do produce shadows. However, models with M<SUB>0</SUB> &lt; 2/3 (or R<SUB>b</SUB> &gt; 3M) have no photon sphere and do not produce a shadow. Instead, they produce an interesting `full-moon' image. These results imply that the presence of a shadow does not by itself prove that a compact object is necessarily a black hole. The object could be a naked singularity with M<SUB>0</SUB> ≥ 2/3, and we will need other observational clues to distinguish the two possibilities. On the other hand, the presence of a full-moon image would certainly rule out a black hole and might suggest a naked singularity with M<SUB>0</SUB> &lt; 2/3. It would be worthwhile to generalize the present study, which is restricted to spherically symmetric models, to rotating black holes and naked singularities.

[]

https://arxiv.org/pdf/1802.08060.pdf

2002PhRvD..66f3505B

Could supermassive black holes be quintessential primordial black holes?

2002-01-01

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

[]

There is growing observational evidence for a population of supermassive black holes (SMBHs) in galactic bulges. We examine in detail the conditions under which these black holes must have originated from primordial black holes (PBHs). We consider the merging and accretion history experienced by SMBHs to find that, whereas it is possible that they were formed by purely astrophysical processes, this is unlikely and most probably a population of primordial progenitors is necessary. We identify the mass distribution and comoving density of this population and then propose a cosmological scenario producing PBHs with the right properties. Although this is not essential we consider PBHs produced at the end of a period of inflation with a blue spectrum of fluctuations. We constrain the value of the spectral tilt in order to obtain the required PBH comoving density. We then assume that PBHs grow by accreting quintessence, showing that their mass scales like the horizon mass while the quintessence field itself is scaling. We find that if scaling is broken just before nucleosynthesis (as is the case with some attractive nonminimally coupled models) we obtain the appropriate PBH mass distribution. Hawking evaporation is negligible in most cases, but we also discuss situations in which the interplay of accretion and evaporation is relevant.

[]

https://arxiv.org/pdf/astro-ph/0204486.pdf

2014PhRvD..90d4057W

Triple points and phase diagrams in the extended phase space of charged Gauss-Bonnet black holes in AdS space

2014-01-01

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

[]

We study the triple points and phase diagrams in the extended phase space of the charged Gauss-Bonnet black holes in d-dimensional anti-de Sitter space, where the cosmological constant appears as a dynamical pressure of the system and its conjugate quantity is the thermodynamic volume of the black holes. Employing the equation of state T=T(v,P), we demonstrate that the information of the phase transition and behavior of the Gibbs free energy are potential encoded in the T-v (T-r<SUB>h</SUB>) line with fixed pressure P. We get the phase diagrams for the charged Gauss-Bonnet black holes with different values of the charge Q and dimension d. The result shows that the small/large black hole phase transitions appear for any d, which is reminiscent of the liquid/gas transition of a Van der Waals type. Moreover, the interesting thermodynamic phenomena, i.e., the triple points and the small/intermediate/large black hole phase transitions are observed for d=6 and Q ∈(0.1705,0.1946).

[]

https://arxiv.org/pdf/1402.2837.pdf

2000MNRAS.318L..35H

The correlation between black hole mass and bulge velocity dispersion in hierarchical galaxy formation models

2000-01-01

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

[]

Recent work has demonstrated that there is a tight correlation between the mass of a black hole and the velocity dispersion of the bulge of its host galaxy. We show that the model of Kauffmann &amp; Haehnelt, in which bulges and supermassive black holes both form during major mergers, produces a correlation between M<SUB>bh</SUB> and σ with a slope and scatter comparable to the observed relation. In the model the M<SUB>bh</SUB>-σ relation is significantly tighter than the correlation between black hole mass and bulge luminosity, or the correlation between bulge luminosity and velocity dispersion. There are two reasons for this: (i) the gas masses of bulge progenitors depend on the velocity dispersion but not on the formation epoch of the bulge, whereas the stellar masses of the progenitors depend on both; (ii) mergers between galaxies move black holes along the observed M<SUB>bh</SUB>-σ relation, even at late times when the galaxies are gas-poor and black holes grow mainly the by merging of pre-existing black holes. We conclude that the small scatter in the observed M<SUB>bh</SUB>-σ relation is consistent with a picture in which bulges and black holes form over a wide range in redshift.

[]

https://arxiv.org/pdf/astro-ph/0007369.pdf

2002A&A...396L..31A

No observational proof of the black-hole event-horizon

2002-01-01

['astrophysics']

[]

Recently, several ways of verifying the existence of black-hole horizons have been proposed. We show here that most of these suggestions are irrelevant to the problem of the horizon, at best they can rule out the presence of conventional baryonic matter in the outer layers of black-hole candidates. More generally, we argue that it is fundamentally impossible to detect in electromagnetic radiation direct evidence for the presence of a black-hole horizon. This applies also to future observations, which would trace very accurately the details of the space-time metric of a body suspected of being a black hole. Specific solutions of Einsteins's equations lack an event horizon, and yet are indistinguishable in their electromagnetic signature from Schwarzschild black holes.

[]

https://arxiv.org/pdf/astro-ph/0207270.pdf

2020JCAP...09..026K

Black holes with scalar hair in light of the Event Horizon Telescope

2020-01-01

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

[]

Searching for violations of the no-hair theorem (NHT) is a powerful way to test gravity, and more generally fundamental physics, particularly with regards to the existence of additional scalar fields. The first observation of a black hole (BH) shadow by the Event Horizon Telescope (EHT) has opened a new direct window onto tests of gravity in the strong-field regime, including probes of violations of the NHT. We consider two scenarios described by the Einstein-Maxwell equations of General Relativity and electromagnetism, to which we add a scalar field. In the first case we consider a minimally-coupled scalar field with a potential, whereas in the second case the field is conformally-coupled to curvature. In both scenarios we construct charged BH solutions, which are found to carry primary scalar hair. We then compute the shadows cast by these two BHs as a function of their electric charge and scalar hair parameter. Comparing these shadows to the shadow of M87* recently imaged by the EHT collaboration, we set constraints on the amount of scalar hair carried by these two BHs. The conformally-coupled case admits a regime for the hair parameter, compatible with EHT constraints, describing a so-called mutated Reissner-Nordström BH: this solution was recently found to effectively mimic a wormhole. Our work provides novel constraints on fundamental physics, and in particular on violations of the no-hair theorem and the existence of additional scalar fields, from the shadow of M87*.

[]

https://arxiv.org/pdf/2005.05992.pdf

2019Natur.565..198K

The corona contracts in a black-hole transient

2019-01-01

['-']

[]

The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months<SUP>1-3</SUP>. When a black hole emerges from quiescence (that is, it `turns on' after accreting material from its companion) it has a very hard (high-energy) X-ray spectrum produced by a hot corona<SUP>4,5</SUP> positioned above its accretion disk, and then transitions to a soft (lower-energy) spectrum dominated by emission from the geometrically thin accretion disk, which extends to the innermost stable circular orbit<SUP>6,7</SUP>. Much debate persists over how this transition occurs and whether it is driven largely by a reduction in the truncation radius of the disk<SUP>8,9</SUP> or by a reduction in the spatial extent of the corona<SUP>10,11</SUP>. Observations of X-ray reverberation lags in supermassive black-hole systems<SUP>12,13</SUP> suggest that the corona is compact and that the disk extends nearly to the central black hole<SUP>14,15</SUP>. Observations of stellar-mass black holes, however, reveal equivalent (mass-scaled) reverberation lags that are much larger<SUP>16</SUP>, leading to the suggestion that the accretion disk in the hard-X-ray state of stellar-mass black holes is truncated at a few hundreds of gravitational radii from the black hole<SUP>17,18</SUP>. Here we report X-ray observations of the black-hole transient MAXI J1820+070<SUP>19,20</SUP>. We find that the reverberation time lags between the continuum-emitting corona and the irradiated accretion disk are 6 to 20 times shorter than previously seen. The timescale of the reverberation lags shortens by an order of magnitude over a period of weeks, whereas the shape of the broadened iron K emission line remains remarkably constant. This suggests a reduction in the spatial extent of the corona, rather than a change in the inner edge of the accretion disk.

[]

https://arxiv.org/pdf/1901.03877.pdf

1999ApJ...522..753M

A Magnetically Switched, Rotating Black Hole Model for the Production of Extragalactic Radio Jets and the Fanaroff and Riley Class Division

1999-01-01

['black hole physics', 'galaxies jets', 'hydrodynamics', 'mhd', 'relativity', '-', 'black hole physics', 'galaxies jets', 'hydrodynamics', 'mhd', 'relativity', '-', 'astrophysics']

[]

A model is presented in which both Fanaroff and Riley (FR) class I and II extragalactic jets are produced by magnetized accretion disk coronae in the ergospheres of rotating black holes. It employs a hybrid version of the Blandford-Payne and Blandford-Znajek magnetohydrodynamic mechanisms (similar to the Punsly-Coroniti model, with the addition of a metric shear-driven dynamo) and a generalized form of the magnetic switch, which is shown to be the MHD analog of the Eddington luminosity. While the jets are produced in the ergospheric accretion disk itself, the output power still is an increasing function of the black hole angular momentum. For high enough spin, the black hole triggers the magnetic switch, producing highly relativistic, kinetic energy-dominated jets instead of magnetic energy-dominated jets for lower spin. The coronal mass densities needed to trigger the switch at the observed FR break power are quite small (~10<SUP>-15</SUP> g cm<SUP>-3</SUP>), implying that the source of the jet material may be either a pair plasma or very tenuous electron-proton corona, not the main accretion disk itself. <P />The model explains the differences in morphology and Mach number between FR I and II sources and the observed trend for massive galaxies (which contain more massive black holes) to undergo the FR I/II transition at higher radio power. It also is consistent with the energy content of extended radio lobes and explains why, because of black hole spin-down, the space density of FR II sources should evolve more rapidly than that of FR I sources. <P />A specific observational test is proposed to distinguish between models like this one, in which the FR I/II division arises from processes near the black hole, and models like Bicknell's, in which the difference is produced by processes in the host galaxy's interstellar medium. If the present model is correct, then the ensemble average speed of parsec-scale jets in sources distinguished by their FR I morphology (not luminosity) should be distinctly slower than that for sources with FR II morphology. The model also suggests the existence of a population of high-redshift, sub-mJy FR I and II radio sources associated with spiral or prespiral galaxies that flared once when their black holes were formed but were never again rekindled by mergers.

[]

https://arxiv.org/pdf/astro-ph/9810352.pdf

2003PhRvD..68d4024C

Quasinormal frequencies of Schwarzschild black holes in anti de Sitter spacetimes: A complete study of the overtone asymptotic behavior

2003-01-01

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

[]

We present a thorough analysis of the quasinormal (QN) behavior associated with the decay of scalar, electromagnetic, and gravitational perturbations of Schwarzschild black holes in anti de Sitter (AdS) spacetimes. As is known, the AdS QN spectrum crucially depends on the relative size of the black hole to the AdS radius. There are three different types of behavior depending on whether the black hole is large, intermediate, or small. The results of previous works, concerning lower overtones for large black holes, are completed here by obtaining higher overtones for all three black hole regimes. There are two major conclusions that one can draw from this work: First, asymptotically for high overtones, all the modes are evenly spaced, and this holds for all three types of regime, large, intermediate, and small black holes, independently of l, where l is the quantum number characterizing the angular distribution; second, the spacing between modes is apparently universal in that it does not depend on the field; i.e., scalar, electromagnetic, and gravitational QN modes all have the same spacing for high overtones. We are also able to prove why scalar and gravitational perturbations are isospectral, asymptotically for high overtones, by introducing appropriate superpartner potentials.

[]

https://arxiv.org/pdf/gr-qc/0305037.pdf

1999MNRAS.306L..31P

Spectral evolution of magnetic flares and time lags in accreting black hole sources

1999-01-01

['astrophysics']

[]

We present a model for the short time-scale spectral variability of accreting black holes. It describes the time-averaged spectra well, and also temporal characteristics such as the power-density spectrum, time/phase lags, and coherence function of Cygnus X-1. We assume that X/γ-rays are produced in compact magnetic flares at radii &lt;~100GMc<SUP>2</SUP> from the central black hole. The tendency for magnetic loops to inflate and detach from the underlying accretion disc causes the spectrum of a flare to evolve from soft to hard because of the decrease of the feedback from the cold disc, so causing time delays between hard and soft photons. We identify the observed time lags with the evolution time-scales of the flares, which are of the order of the Keplerian time-scale. We model the overall temporal variability using a pulse avalanche model in which each flare has a certain probability of triggering a neighbouring flare, thus occasionally producing long avalanches. The duration of the avalanches determines the Fourier frequencies at which most of the power emerges.

[]

https://arxiv.org/pdf/astro-ph/9811306.pdf

2007ApJ...662..504B

On the Rarity of Double Black Hole Binaries: Consequences for Gravitational Wave Detection

2007-01-01

['stars binaries close', 'black hole physics', 'gravitational waves', '-', '-', 'astrophysics']

[]

Double black hole binaries are among the most important sources of gravitational radiation for ground-based detectors such as LIGO or VIRGO. Even if formed with lower efficiency than double neutron star binaries, they could dominate the predicted detection rates, since black holes are more massive than neutron stars and therefore could be detected at greater distances. Here we discuss an evolutionary process that could very significantly limit the formation of close double black hole binaries: the vast majority of their potential progenitors undergo a common-envelope (CE) phase while the donor, one of the massive binary components, is evolving through the Hertzsprung gap. Our latest theoretical understanding of the CE process suggests that this will probably lead to a merger, inhibiting double black hole formation. Barring uncertainties in the physics of CE evolution, we use population synthesis calculations and find that the corresponding reduction in the merger rate of double black holes formed in galactic fields is so great (by ~500) that their contribution to inspiral detection rates for ground-based detectors could become relatively small (~1 in 10) compared to double neutron star binaries. A similar process also reduces the merger rates for double neutron stars, by a factor of ~5, eliminating most of the previously predicted ultracompact NS-NS systems. Our predicted detection rates for Advanced LIGO are now much lower for double black holes (~2 yr<SUP>-1</SUP>), but are still quite high for double neutron stars (~20 yr<SUP>-1</SUP>). If double black holes were found to be dominant in the detected inspiral signals, this could indicate that they mainly originate from dense star clusters (not included here) or that our theoretical understanding of the CE phase requires significant revision.

[]

https://arxiv.org/pdf/astro-ph/0612032.pdf

2007PhRvD..76b4016D

Wormholes as black hole foils

2007-01-01

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

[]

We study to what extent wormholes can mimic the observational features of black holes. It is surprisingly found that many features that could be thought of as “characteristic” of a black hole (endowed with an event horizon) can be closely mimicked by a globally static wormhole, having no event horizon. This is the case for the apparently irreversible accretion of matter down a hole, no-hair properties, quasi-normal-mode ringing, and even the dissipative properties of black hole horizons, such as a finite surface resistivity equal to 377 Ohms. The only way to distinguish the two geometries on an observationally reasonable time scale would be through the detection of Hawking’s radiation, which is, however, too weak to be of practical relevance for astrophysical black holes. We point out the existence of an interesting spectrum of quantum microstates trapped in the throat of a wormhole which could be relevant for storing the information lost during a gravitational collapse.

[]

https://arxiv.org/pdf/0704.2667.pdf

2007ApJ...662..131S

The Black Hole Mass-Galaxy Bulge Relationship for QSOs in the Sloan Digital Sky Survey Data Release 3

2007-01-01

['black hole physics', 'galaxies active', 'galaxies quasars', 'astrophysics']

[]

We investigate the relationship between black hole mass, M<SUB>BH</SUB>, and host galaxy velocity dispersion, σ<SUB>*</SUB>, for QSOs in Data Release 3 of the Sloan Digital Sky Survey. We derive M<SUB>BH</SUB> from the broad Hβ line width and continuum luminosity and the bulge stellar velocity dispersion from the narrow [O III] line width (σ<SUB>[OIII]</SUB>). At higher redshifts, we use Mg II and [O II] in place of Hβ and [O III]. For redshifts z&lt;0.5, our results agree with the M<SUB>BH</SUB>-σ<SUB>*</SUB> relationship for nearby galaxies. For 0.5&lt;z&lt;1.2, the M<SUB>BH</SUB>-σ<SUB>*</SUB> relationship appears to show evolution with redshift in the sense that the bulges are too small for their black holes. However, we find that part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the QSO luminosity. Accounting for these biases, we find ~0.2 dex evolution in the M<SUB>BH</SUB>-σ<SUB>*</SUB> relationship between now and redshift z~1.

[]

https://arxiv.org/pdf/astro-ph/0612568.pdf

2008ApJ...678L..81K

A Recoiling Supermassive Black Hole in the Quasar SDSS J092712.65+294344.0?

2008-01-01

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

[]

We present SDSS J092712.65+294344.0 as the best candidate to date for a recoiling supermassive black hole (SMBH). SDSS J0927+2943 shows an exceptional optical emission-line spectrum with two sets of emission lines: one set of very narrow emission lines, and a second set of broad Balmer and broad high-ionization forbidden lines which are blueshifted by 2650 km s<SUP>-1</SUP> relative to the set of narrow emission lines. This observation is most naturally explained if the SMBH was ejected from the core of the galaxy, carrying with it the broad-line gas while leaving behind the bulk of the narrow-line gas. We show that the observed properties of SDSS J0927+2943 are consistent with predictions and expectations from recent numerical relativity simulations which demonstrate that SMBHs can receive kicks up to several thousand km s<SUP>-1</SUP> due to anisotropic emission of gravitational waves during the coalescence of a binary. Our detection of a strong candidate for a rapidly recoiling SMBH implies that kicks large enough to remove SMBHs completely from their host galaxies do occur, with important implications for models of black hole and galaxy assembly at the epoch of structure formation, and for recoil models.

[]

https://arxiv.org/pdf/0804.4585.pdf

2009MNRAS.397.2148G

Quantifying the coexistence of massive black holes and dense nuclear star clusters

2009-01-01

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

[]

In large spheroidal stellar systems, such as elliptical galaxies, one invariably finds a 10<SUP>6</SUP>-10<SUP>9</SUP>M<SUB>solar</SUB> supermassive black hole at their centre. In contrast, within dwarf elliptical galaxies one predominantly observes a 10<SUP>5</SUP>-10<SUP>7</SUP>M<SUB>solar</SUB> nuclear star cluster. To date, few galaxies have been found with both types of nuclei coexisting and even less have had the masses determined for both central components. Here, we identify one dozen galaxies housing nuclear star clusters and supermassive black holes whose masses have been measured. This doubles the known number of such hermaphrodite nuclei - which are expected to be fruitful sources of gravitational radiation. Over the host spheroid (stellar) mass range 10<SUP>8</SUP>-10<SUP>11</SUP>M<SUB>solar</SUB>, we find that a galaxy's nucleus-to-spheroid (baryon) mass ratio is not a constant value but decreases from a few per cent to ~0.3 per cent such that log[(M<SUB>BH</SUB> + M<SUB>NC</SUB>)/M<SUB>sph</SUB>] = -(0.39 +/- 0.07) log[M<SUB>sph</SUB>/10<SUP>10</SUP>M<SUB>solar</SUB>] - (2.18 +/- 0.07). Once dry merging commences and the nuclear star clusters disappear, this ratio is expected to become a constant value. <P />As a byproduct of our investigation, we have found that the projected flux from resolved nuclear star clusters is well approximated with Sérsic functions having a range of indices from ~0.5 to ~3, the latter index describing the Milky Way's nuclear star cluster.

[]

https://arxiv.org/pdf/0907.5250.pdf

2009JHEP...09..123P

The black hole and cosmological solutions in IR modified Hořava gravity

2009-01-01

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

[]

Recently Hořava proposed a renormalizable gravity theory in four dimensions which reduces to Einstein gravity with a non-vanishing cosmological constant in IR but with improved UV behaviors. Here, I study an IR modification which breaks ``softly'' the detailed balance condition in Hořava model and allows the asymptotically flat limit as well. I obtain the black hole and cosmological solutions for ``arbitrary'' cosmological constant that represent the analogs of the standard Schwarzschild-(A)dS solutions which can be asymptotically (A)dS as well as flat and I discuss their thermodynamical properties. I also obtain solutions for FRW metric with an arbitrary cosmological constant. I study its implication to the dark energy and find that it seems to be consistent with current observational data.

[]

https://arxiv.org/pdf/0905.4480.pdf

2007PhRvD..75b4005B

``Kludge'' gravitational waveforms for a test-body orbiting a Kerr black hole

2007-01-01

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

[]

One of the most exciting potential sources of gravitational waves for low-frequency, space-based gravitational wave (GW) detectors such as the proposed Laser Interferometer Space Antenna (LISA) is the inspiral of compact objects into massive black holes in the centers of galaxies. The detection of waves from such “extreme mass ratio inspiral” systems (EMRIs) and extraction of information from those waves require template waveforms. The systems’ extreme mass ratio means that their waveforms can be determined accurately using black hole perturbation theory. Such calculations are computationally very expensive. There is a pressing need for families of approximate waveforms that may be generated cheaply and quickly but which still capture the main features of true waveforms. In this paper, we introduce a family of such kludge waveforms and describe ways to generate them. Different kinds of kludges have already been used to scope out data analysis issues for LISA. The models we study here are based on computing a particle’s inspiral trajectory in Boyer-Lindquist coordinates, and subsequent identification of these coordinates with flat-space spherical polar coordinates. A gravitational waveform may then be computed from the multipole moments of the trajectory in these coordinates, using well-known solutions of the linearised gravitational perturbation equations in flat space time. We compute waveforms using a standard slow-motion quadrupole formula, a quadrupole/octupole formula, and a fast-motion, weak-field formula originally developed by Press. We assess these approximations by comparing to accurate waveforms obtained by solving the Teukolsky equation in the adiabatic limit (neglecting GW backreaction). We find that the kludge waveforms do extremely well at approximating the true gravitational waveform, having overlaps with the Teukolsky waveforms of 95% or higher over most of the parameter space for which comparisons can currently be made. Indeed, we find these kludges to be of such high quality (despite their ease of calculation) that it is possible they may play some role in the final search of LISA data for EMRIs.

[]

https://arxiv.org/pdf/gr-qc/0607007.pdf

2019PhRvL.123r1101Y

Hierarchical Black Hole Mergers in Active Galactic Nuclei

2019-01-01

['-']

[]

The origins of the stellar-mass black hole mergers discovered by LIGO/Virgo are still unknown. Here we show that if migration traps develop in the accretion disks of active galactic nuclei (AGNs) and promote the mergers of their captive black holes, the majority of black holes within disks will undergo hierarchical mergers—with one of the black holes being the remnant of a previous merger. 40% of AGN-assisted mergers detected by LIGO/Virgo will include a black hole with mass ≳50 M<SUB>⊙</SUB> , the mass limit from stellar core collapse. Hierarchical mergers at traps in AGNs will exhibit black hole spins (anti)aligned with the binary's orbital axis, a distinct property from other hierarchical channels. Our results suggest, although not definitively (with odds ratio of ∼1 ), that LIGO's heaviest merger so far, GW170729, could have originated from this channel.

[]

https://arxiv.org/pdf/1906.09281.pdf

2013ApJ...772..112S

Unleashing Positive Feedback: Linking the Rates of Star Formation, Supermassive Black Hole Accretion, and Outflows in Distant Galaxies

2013-01-01

['galaxies active', 'galaxies evolution', 'galaxies star clusters', 'galaxy formation', '-']

[]

Pressure-regulated star formation is a simple variant on the usual supernova-regulated star formation efficiency that controls the global star formation rate as a function of cold gas content in star-forming galaxies, and accounts for the Schmidt-Kennicutt law in both nearby and distant galaxies. Inclusion of active galactic nucleus (AGN) induced pressure, by jets and/or winds that flow back onto a gas-rich disk, can lead, under some circumstances, to significantly enhanced star formation rates, especially at high redshift and most likely followed by the more widely accepted phase of star formation quenching. Simple expressions are derived that relate supermassive black hole growth, star formation, and outflow rates. The ratios of black hole to spheroid mass and of both black hole accretion and outflow rates to star formation rate are predicted as a function of time. I suggest various tests of the AGN-triggered star formation hypothesis.

[]

https://arxiv.org/pdf/1305.5840.pdf

2010Natur.466.1082M

Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers

2010-01-01

['-']

[]

Observations of distant quasars indicate that supermassive black holes of billions of solar masses already existed less than a billion years after the Big Bang. Models in which the `seeds' of such black holes form by the collapse of primordial metal-free stars cannot explain the rapid appearance of these supermassive black holes because gas accretion is not sufficiently efficient. Alternatively, these black holes may form by direct collapse of gas within isolated protogalaxies, but current models require idealized conditions, such as metal-free gas, to prevent cooling and star formation from consuming the gas reservoir. Here we report simulations showing that mergers between massive protogalaxies naturally produce the conditions for direct collapse into a supermassive black hole with no need to suppress cooling and star formation. Merger-driven gas inflows give rise to an unstable, massive nuclear gas disk of a few billion solar masses, which funnels more than 10<SUP>8</SUP> solar masses of gas to a sub-parsec-scale gas cloud in only 100,000 years. The cloud undergoes gravitational collapse, which eventually leads to the formation of a massive black hole. The black hole can subsequently grow to a billion solar masses on timescales of about 10<SUP>8</SUP> years by accreting gas from the surrounding disk.

[]

https://arxiv.org/pdf/0912.4262.pdf

2018PhRvL.120p1102L

First Higher-Multipole Model of Gravitational Waves from Spinning and Coalescing Black-Hole Binaries

2018-01-01

['-']

[]

Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipoles (ℓ=2 ,|m |=2 ) of the radiation during inspiral, merger, and ringdown. We introduce a simple method to include the subdominant multipoles to binary black hole gravitational waveforms, given a frequency-domain model for the dominant multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two. No additional tuning to numerical-relativity simulations is required. We apply a variant of this method to the nonprecessing PhenomD model. The result, PhenomHM, constitutes the first higher-multipole model of spinning and coalescing black-hole binaries, and currently includes the (ℓ,|m |)=(2 ,2 ),(3 ,3 ),(4 ,4 ),(2 ,1 ),(3 ,2 ),(4 ,3 ) radiative moments. Comparisons with numerical-relativity waveforms demonstrate that PhenomHM is more accurate than dominant-multipole-only models for all binary configurations, and typically improves the measurement of binary properties.

[]

https://arxiv.org/pdf/1708.00404.pdf

2002PhRvD..66d4019S

Gravity wave analogues of black holes

2002-01-01

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

[]

It is demonstrated that gravity waves of a flowing fluid in a shallow basin can be used to simulate phenomena around black holes in the laboratory. Since the speed of the gravity waves as well as their high-wave-number dispersion (subluminal vs superluminal) can be adjusted easily by varying the height of the fluid (and its surface tension) this scenario has certain advantages over the sonic and dielectric black hole analogs, for example, although its use in testing quantum effects is dubious. It can be used to investigate the various classical instabilities associated with black (and white) holes experimentally, including positive and negative norm mode mixing at horizons.

[]

https://arxiv.org/pdf/gr-qc/0205099.pdf

1998ApJ...502L...9F

Helium Star/Black Hole Mergers: A New Gamma-Ray Burst Model

1998-01-01

['gamma rays', 'gamma rays', 'black hole physics', 'black hole physics', 'gamma rays', 'gamma rays', 'astrophysics']

[]

We present a model for gamma-ray bursts (GRBs) in which a stellar mass black hole acquires a massive accretion disk by merging with the helium core of its red giant companion. The black hole enters the helium core after it, or its neutron star progenitor, first experiences a common envelope phase that carries it inward through the hydrogen envelope. Accretion of the last several solar masses of helium occurs on a timescale of roughly a minute and provides a neutrino luminosity of approximately 10<SUP>51</SUP>-10<SUP>52</SUP> ergs s<SUP>-1</SUP>. Neutrino annihilation, 0.01%-0.1% efficient, along the rotational axis then gives a baryon-loaded fireball of electron-positron pairs and radiation (about 10<SUP>50</SUP> ergs total) whose beaming and relativistic interaction with the circumstellar material makes the GRB (see, e.g., Rees &amp; Mészáros). The useful energy can be greatly increased if energy can be extracted from the rotational energy of the black hole by magnetic interaction with the disk. Such events should occur at a rate comparable to that of merging neutron stars and black hole neutron star pairs and may be responsible for long complex GRBs but not short hard ones.

[]

https://arxiv.org/pdf/astro-ph/9804167.pdf

2008MNRAS.386.2242H

The black hole mass-stellar velocity dispersion correlation: bulges versus pseudo-bulges

2008-01-01

['black hole physics', 'galaxies bulges', 'galaxies formation', 'galaxies fundamental parameters', 'galaxies nuclei', 'astrophysics']

[]

We investigate the correlation between the supermassive black holes (SMBHs) mass (M<SUB>bh</SUB>) and the stellar velocity dispersion (σ<SUB>*</SUB>) in two types of host galaxies: the early-type bulges (disc galaxies with classical bulges or elliptical galaxies) and pseudo-bulges. In the form log(M<SUB>bh</SUB>/M<SUB>solar</SUB>) = α + β log (σ<SUB>*</SUB>/200kms<SUP>-1</SUP>), the best-fitting results for the 39 early-type bulges are the slope β = 4.06 +/- 0.28 and the normalization α = 8.28 +/- 0.05; the best-fitting results for the nine pseudo-bulges are β = 4.5 +/- 1.3 and α = 7.50 +/- 0.18. Both relations have intrinsic scatter in logM<SUB>bh</SUB> of &lt;~0.27 dex. The M<SUB>bh</SUB>-σ<SUB>*</SUB> relation for pseudo-bulges is different from the relation in the early-type bulges over the 3σ significance level. The contrasting relations indicate the formation and growth histories of SMBHs depend on their host type. The discrepancy between the slope of the M<SUB>bh</SUB>-σ<SUB>*</SUB> relations using different definition of velocity dispersion vanishes in our sample, a uniform slope will constrain the coevolution theories of the SMBHs and their host galaxies more effectively. We also find the slope for the `core' elliptical galaxies at the high-mass range of the relation appears steeper (β ~= 5-6), which may be the imprint of their origin of dissipationless mergers.

[]

https://arxiv.org/pdf/0801.1481.pdf

2016ApJ...819L..21L

Electromagnetic Counterparts to Black Hole Mergers Detected by LIGO

2016-01-01

['gamma rays', 'gravitational waves', '-', '-', '-', '-', '-']

[]

Mergers of stellar-mass black holes (BHs), such as GW150914 observed by Laser Interferometer Gravitational Wave Observatory (LIGO), are not expected to have electromagnetic counterparts. However, the Fermi GBM detector identified a γ-ray transient 0.4 s after the gravitational wave (GW) signal GW150914 with consistent sky localization. I show that the two signals might be related if the BH binary detected by LIGO originated from two clumps in a dumbbell configuration that formed when the core of a rapidly rotating massive star collapsed. In that case, the BH binary merger was followed by a γ-ray burst (GRB) from a jet that originated in the accretion flow around the remnant BH. A future detection of a GRB afterglow could be used to determine the redshift and precise localization of the source. A population of standard GW sirens with GRB redshifts would provide a new approach for precise measurements of cosmological distances as a function of redshift.

[]

https://arxiv.org/pdf/1602.04735.pdf

2016ApJ...816...65A

Black Hole Mergers and Blue Stragglers from Hierarchical Triples Formed in Globular Clusters

2016-01-01

['stars blue stragglers', '-', 'gravitational waves', '-', '-']

[]

Hierarchical triple-star systems are expected to form frequently via close binary-binary encounters in the dense cores of globular clusters (GCs). In a sufficiently inclined triple, gravitational interactions between the inner and outer binary can cause large-amplitude oscillations in the eccentricity of the inner orbit (“Lidov-Kozai (LK) cycles”), which can lead to a collision and merger of the two inner components. In this paper we use Monte Carlo models of dense star clusters to identify all triple systems formed dynamically and we compute their evolution using a highly accurate three-body integrator which incorporates relativistic and tidal effects. We find that a large fraction of these triples evolve through a non-secular dynamical phase which can drive the inner binary to higher eccentricities than predicted by the standard secular perturbation theory (even including octupole-order terms). We place constraints on the importance of LK-induced mergers for producing: (I) gravitational wave sources detectable by Advanced LIGO (aLIGO), for triples with an inner pair of stellar black holes (BHs); and (II) blue straggler stars, for triples with main-sequence-star components. We find a realistic aLIGO detection rate of BH mergers due to the LK mechanism of ∼1 yr<SUP>-1</SUP>, with about 20% of these having a finite eccentricity when they first chirp into the aLIGO frequency band. While rare, these events are likely to dominate among eccentric compact object inspirals that are potentially detectable by aLIGO. For blue stragglers, we find that the LK mechanism can contribute up to ∼10% of their total numbers in GCs.

[]

https://arxiv.org/pdf/1509.05080.pdf

2011NatPh...7..195T

Twisting of light around rotating black holes

2011-01-01

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

[]

Kerr black holes are among the most intriguing predictions of Einstein's general relativity theory. These rotating massive astrophysical objects drag and intermix their surrounding space and time, deflecting and phase-modifying light emitted near them. We have found that this leads to a new relativistic effect that imprints orbital angular momentum on such light. Numerical experiments, based on the integration of the null geodesic equations of light from orbiting point-like sources in the Kerr black hole equatorial plane to an asymptotic observer, indeed identify the phase change and wavefront warping and predict the associated light-beam orbital angular momentum spectra. Setting up the best existing telescopes properly, it should be possible to detect and measure this twisted light, thus allowing a direct observational demonstration of the existence of rotating black holes. As non-rotating objects are more an exception than a rule in the Universe, our findings are of fundamental importance.

[]

https://arxiv.org/pdf/1104.3099.pdf

1995PhRvD..52.6178S

Charged black points in general relativity coupled to the logarithmic U(1) gauge theory

1995-01-01

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

[]

The exact solution for a static spherically symmetric field outside a charged point particle is found in a nonlinear U(1) gauge theory with a logarithmic Lagrangian. The electromagnetic self-mass is finite, and for a particular relation between mass, charge, and the value of the nonlinearity coupling constant λ, the electromagnetic contribution to the Schwarzschild mass is equal to the total mass. If we also require that the singularity at the origin be hidden behind a horizon, the mass is fixed to be slightly less than the charge. This object is a black point.

[]

https://arxiv.org/pdf/hep-th/9509033.pdf

1997ApJ...482..448N

Advection-dominated Accretion Model of the Black Hole V404 Cygni in Quiescence

1997-01-01

['accretion', 'accretion disks', 'stars binaries close', 'black hole physics', '-', 'astronomy x rays', 'astrophysics']

[]

We have analyzed archival ASCA data on the soft X-ray transient source V404 Cyg in quiescence. We find that in the energy range 0.7-8.5 keV the spectrum is a hard power law with a photon spectral index between 1.8 and 2.6 (90% confidence limits). We present a model of V404 Cyg in which the accretion flow has two components: (1) an outer thin disk with a small annular extent and (2) a large interior region where the flow is advection dominated. Nearly all the radiation in the infrared, optical, UV, and X-ray bands is from the advection-dominated zone; the thin disk radiates primarily in the infrared where it contributes about 10% of the observed flux. The spectrum we calculate with this model is in excellent agreement with the ASCA X-ray data presented here, as well as with previous optical data. Moreover, the fit is very insensitive to the choice of parameters such as black hole mass, orbital inclination, viscosity coefficient α, and magnetic field strength. We consider the success of the model to be strong support for the advection-dominated accretion paradigm, and further evidence of the black hole nature of V404 Cyg. We discuss strategies whereby systems with advection-dominated accretion could be used to prove the reality of event horizons in black holes.

[]

https://arxiv.org/pdf/astro-ph/9610014.pdf

2008ApJ...676.1008N

Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri

2008-01-01

['black hole physics', 'clusters globular', 'stars kinematics and dynamics', 'astrophysics']

[]

The globular cluster ω Centauri is one of the largest and most massive members of the galactic system. However, its classification as a globular cluster has been challenged making it a candidate for being the stripped core of an accreted dwarf galaxy; this together with the fact that it has one of the largest velocity dispersions for star clusters in our galaxy makes it an interesting candidate for harboring an intermediate-mass black hole. We measure the surface brightness profile from integrated light on an HST ACS image of the center, and find a central power-law cusp of logarithmic slope -0.08. We also analyze Gemini GMOS-IFU kinematic data for a 5'' × 5'' field centered on the nucleus of the cluster, as well as for a field 14'' away. We detect a clear rise in the velocity dispersion from 18.6 km s<SUP>-1</SUP> at 14'' to 23 km s<SUP>-1</SUP> in the center. A rise in the velocity dispersion could be due to a central black hole, a central concentration of stellar remnants, or a central orbital structure that is radially biased. We discuss each of these possibilities. An isotropic, spherical dynamical model implies a black hole mass of 4.0<SUB>-1.0</SUB><SUP>+0.75</SUP> × 10<SUP>4</SUP> M<SUB>⊙</SUB>, and excludes the no black hole case at greater than 99% significance. We have also run flattened, orbit-based models and find similar results. While our preferred model is the existence of a central black hole, detailed numerical simulations are required to confidently rule out the other possibilities.

[]

https://arxiv.org/pdf/0801.2782.pdf

2002A&A...382L..13K

Population X: Are the super-Eddington X-ray sources beamed jets in microblazars or intermediate mass black holes?

2002-01-01

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

[]

Recent X-ray observations reveal an increasing number of X-ray sources in nearby galaxies exceeding luminosities of L<SUB>x</SUB>&gt;~2 x 10<SUP>39</SUP> erg s<SUP>-1</SUP>. Assuming isotropic emission, the Eddington limit suggests a population of intermediate-mass black holes of M<SUB>⊙</SUB>&gt;&gt;10 M<SUB>sun</SUB>. However, Markoff et al. (\cite{MarkoffFalckeFender2001}) proposed that jets may be contributing to the X-ray emission from X-ray binaries (XRBs), implying that some X-ray sources may be relativistically beamed. This could reduce the required black hole masses to standard values. To test this hypothesis, we investigate a simple X-ray population synthesis model for X-ray point sources in galaxies with relativistic beaming and compare it with an isotropic emission model. The model is used to explain a combined data set of X-ray point sources in nearby galaxies. We show that the current distributions are consistent with black hole masses M<SUB>sun</SUB>&lt;~10 and bulk Lorentz factors for jets in microquasars of gamma<SUB>j</SUB> ~ 5. Alternatively, intermediate mass black holes up to 1000 M<SUB>sun</SUB> are required which are distributed in a powerlaw with roughly (dN)/(dM) ~ M<SUP>-2</SUP>.

[]

https://arxiv.org/pdf/astro-ph/0112385.pdf

2010CQGra..27v5002O

A new cubic theory of gravity in five dimensions: black hole, Birkhoff's theorem and C-function

2010-01-01

['-', '-']

[]

We present a new cubic theory of gravity in five dimensions which has second-order traced field equations, analogous to BHT new massive gravity in three dimensions. Moreover, for static spherically symmetric spacetimes all the field equations are of second order, and the theory admits a new asymptotically locally flat black hole. Furthermore, we prove the uniqueness of this solution, study its thermodynamical properties and show the existence of a C-function for the theory following the arguments of Anber and Kastor (2008 J. High Energy Phys. JHEP05(2008)061 (arXiv:0802.1290 [hep-th])) in pure Lovelock theories. Finally, we include the Einstein-Gauss-Bonnet and cosmological terms and find new asymptotically AdS black holes at the point where the three maximally symmetric solutions of the theory coincide. These black holes may also possess a Cauchy horizon.

[]

https://arxiv.org/pdf/1003.4773.pdf

2003IJMPA..18.1843C

Black Hole and Brane Production in TeV Gravity

2003-01-01

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

[]

In models with large extra dimensions, particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate nonperturbative gravitational objects such as black holes and branes. The formation and the subsequent decay of these super-Planckian objects would be detectable in particle colliders and high energy cosmic ray detectors, and have interesting implications in cosmology and astrophysics. In this paper we present a review of black hole and brane production in TeV-scale gravity.

[]

https://arxiv.org/pdf/hep-ph/0210296.pdf

2005MNRAS.358..168S

Radiative feedback from quasars and the growth of massive black holes in stellar spheroids

2005-01-01

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

[]

We discuss the importance of feedback via photoionization and Compton heating on the co-evolution of massive black holes (MBHs) at the centre of spheroidal galaxies, and their stellar and gaseous components. We first assess the energetics of the radiative feedback from a typical quasar on the ambient interstellar medium (ISM). We then demonstrate that the observed M<SUB>BH</SUB>-σ relation could be established following the conversion of most of the gas of an elliptical progenitor into stars, specifically when the gas-to-stars mass ratio in the central regions has dropped to a low level ~0.01 or less, so that gas cooling is no longer able to keep up with the radiative heating by the growing central massive black hole (MBH). A considerable amount of the remaining gas will be expelled and both MBH accretion and star formation will proceed at significantly reduced rates thereafter, in agreement with observations of present-day ellipticals. We find further support for this scenario by evolving over an equivalent Hubble time a simple, physically based toy model that additionally takes into account the mass and energy return for the spheroid evolving stellar population, a physical ingredient often neglected in similar approaches.

[]

https://arxiv.org/pdf/astro-ph/0411086.pdf

2015ApJ...801...38W

The Black Hole Mass-Stellar Velocity Dispersion Relation of Narrow-line Seyfert 1 Galaxies

2015-01-01

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

[]

Narrow-line Seyfert 1 galaxies (NLS1s) are arguably one of the key active galactic nucleus (AGN) subclasses in investigating the origin of the black hole mass-stellar velocity dispersion ({{M}<SUB>BH</SUB>}-{{σ }<SUB>*</SUB>}) relation because of their high accretion rate and significantly low {{M}<SUB>BH</SUB>} . Currently, it is under discussion whether present-day NLS1s offset from the {{M}<SUB>BH</SUB>}-{{σ }<SUB>*</SUB>} relation. Using the directly measured stellar velocity dispersion of 93 NLS1s at z &lt; 0.1, and {{M}<SUB>BH</SUB>} estimates based on the updated mass estimators, we investigate the {{M}<SUB>BH</SUB>}-{{σ }<SUB>*</SUB>} relation of NLS1s in comparison with broad-line AGNs. We find no strong evidence that the NLS1s deviates from the {{M}<SUB>BH</SUB>}-{{σ }<SUB>*</SUB>} relation, which is defined by reverberation-mapped type 1 AGNs and quiescent galaxies. However, there is a clear trend of the offset with the host galaxy morphology, i.e., galaxies that are more inclined toward the LOS have higher stellar velocity dispersions, suggesting that the rotational broadening plays a role in measuring stellar velocity dispersion based on the single-aperture spectra from the Sloan Digital Sky Survey. In addition, we provide the virial factor log f=0.05+/- 0.12 (f = 1.12), for {{M}<SUB>BH</SUB>} estimators based on the FWHM of Hβ, by jointly fitting the {{M}<SUB>BH</SUB>}-{{σ }<SUB>*</SUB>} relation using quiescent galaxies and reverberation-mapped AGNs.

[]

https://arxiv.org/pdf/1412.7225.pdf

2014ApJ...782...45D

Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. I. First Results from a New Reverberation Mapping Campaign

2014-01-01

['accretion', 'accretion disks', 'black hole physics', 'galaxies active', '-']

[]

We report first results from a large project to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). Such objects may be different from other AGNs in being powered by slim accretion disks and showing saturated accretion luminosities, but both are not yet fully understood. The results are part of a large reverberation mapping (RM) campaign using the 2.4 m Shangri-La telescope at the Yunnan Observatory in China. The goals are to investigate the gas distribution near the BH and the properties of the central accretion disks, to measure BH mass and Eddington ratios, and to test the feasibility of using such objects as a new type of cosmological candles. The paper presents results for three objects, Mrk 335, Mrk 142, and IRAS F12397+3333, with Hβ time lags relative to the 5100 Å continuum of 10.6^{+1.7}_{-2.9}, 6.4^{+0.8}_{-2.2} and 11.4^{+2.9}_{-1.9} days, respectively. The corresponding BH masses are (8.3_{-3.2}^{+2.6})\times 10^6\,M_{\odot }, (3.4_{-1.2}^{+0.5})\times 10^6\,M_{\odot }, and (7.5_{-4.1}^{+4.3})\times 10^6\,M_{\odot }, and the lower limits on the Eddington ratios are 0.6, 2.3, and 4.6 for the minimal radiative efficiency of 0.038. Mrk 142 and IRAS F12397+333 (extinction corrected) clearly deviate from the currently known relation between Hβ lag and continuum luminosity. The three Eddington ratios are beyond the values expected in thin accretion disks and two of them are the largest measured so far among objects with RM-based BH masses. We briefly discuss implications for slim disks, BH growth, and cosmology.

[]

https://arxiv.org/pdf/1310.4107.pdf

1996CQGra..13.2707A

Making anti-de Sitter black holes

1996-01-01

['-']

[]

It is known from the work of Bañados et al that a spacetime with event horizons (much like the Schwarzschild black hole) can be obtained from (2 + 1)-dimensional anti-de Sitter space through a suitable identification of points. We point out that this can be done in 3 + 1 dimensions as well. In this way we obtain black holes with event horizons that are tori or Riemann surfaces of genus higher than one. They can have either one or two asymptotic regions (with non-standard topology). Locally, the spacetime is isometric to anti-de Sitter space.

[]

https://arxiv.org/pdf/gr-qc/9604005.pdf

2015MNRAS.454.3150G

MOCCA code for star cluster simulations - IV. A new scenario for intermediate mass black hole formation in globular clusters

2015-01-01

['methods numerical', 'stars black holes', 'clusters globular', '-']

[]

We discuss a new scenario for the formation of intermediate mass black holes (IMBHs) in dense star clusters. In this scenario, IMBHs are formed as a result of dynamical interactions of hard binaries containing a stellar-mass black hole (BH), with other stars and binaries. We discuss the necessary conditions to initiate the process of intermediate mass BH formation and the influence of an IMBH on the host global globular cluster (GC) properties. We discuss two scenarios for IMBH formation. The SLOW and FAST scenarios. They occur later or earlier in the cluster evolution and require smaller or extremely large central densities, respectively. In our simulations, the formation of IMBHs is highly stochastic. In general, higher formation probabilities follow from larger cluster concentrations (i.e. central densities). We further discuss possible observational signatures of the presence of IMBHs in GCs that follow from our simulations. These include the spatial and kinematic structure of the host cluster, possible radio, X-ray and gravitational wave emissions due to dynamical collisions or mass transfer and the creation of hypervelocity main-sequence escapers during strong dynamical interactions between binaries and an IMBH. All simulations discussed in this paper were performed with the MOCCA (MOnte Carlo Cluster simulAtor) Monte Carlo code. MOCCA accurately follows most of the important physical processes that occur during the dynamical evolution of star clusters but, as with other dynamical codes, it approximates the dissipative processes connected with stellar collisions and binary mergers.

[]

https://arxiv.org/pdf/1506.05234.pdf

2006PhRvD..73h4009S

Thermodynamics of de Sitter black holes: Thermal cosmological constant

2006-01-01

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

[]

We study the thermodynamic properties associated with the black hole event horizon and the cosmological horizon for black hole solutions in asymptotically de Sitter spacetimes. We examine thermodynamics of these horizons on the basis of the conserved charges according to Teitelboim’s method. In particular, we have succeeded in deriving the generalized Smarr formula among thermodynamical quantities in a simple and natural way. We then show that cosmological constant must decrease when one takes into account the quantum effect. These observations have been obtained if and only if the cosmological constant plays the role of a thermodynamical state variable. We also touch upon the relation between inflation of our universe and a phase transition of black holes.

[]

https://arxiv.org/pdf/hep-th/0602269.pdf

1996NuPhB.475..179K

Intersecting M-branes as four-dimensional black holes

1996-01-01

['-']

[]

We present two {1}/{8} supersymmetric intersecting p-brane solutions of 11-dimensional super-gravity which upon compactification to four dimensions reduce to extremal dyonic black holes with finite area of horizon. The first solution is a configuration of three intersecting 5-branes with an extra momentum flow along the common string. The second describes a system of two 2-branes and two 5-branes. Related (by compactification and T-duality) solution of type IIB theory corresponds to a completely symmetric configuration of four intersecting 3-branes. We suggest methods for counting the BPS degeneracy of three intersecting 5-branes which, in the macroscopic limit, reproduce the Bekenstein-Hawking entropy.

[]

https://arxiv.org/pdf/hep-th/9604166.pdf

2003ApJ...594L..71A

Primordial Black Holes as Dark Matter: The Power Spectrum and Evaporation of Early Structures

2003-01-01

['black hole physics', 'cosmology observations', 'cosmology theory', 'cosmology dark matter', 'cosmology large scale structure of the universe', 'galaxies quasars', 'astrophysics', '-', '-']

[]

We consider the possibility that massive primordial black holes are the dominant form of dark matter. Black hole formation adds a Poisson noise to the matter density fluctuations. We use Lyα forest observations to constrain this Poisson term, which constrains the black hole masses to be less than approximately a few times 10<SUP>4</SUP> M<SUB>solar</SUB>. We also find that structures with less than ~10<SUP>3</SUP> black holes evaporate by now.

[]

https://arxiv.org/pdf/astro-ph/0302035.pdf

2003GReGr..35.1733A

Geometry of Black Hole Thermodynamics

2003-01-01

['-']

[]

The Hessian of the entropy function can be thought of as a metric tensor on the state space. In the context of thermodynamical fluctuation theory Ruppeiner has argued that the Riemannian geometry of this metric gives insight into the underlying statistical mechanical system; the claim is supported by numerous examples. We study this geometry for some families of black holes. It is flat for the BTZ and Reissner-Nordström black holes, while curvature singularities occur for the Reissner-Nordström-anti-de Sitter and Kerr black holes.

[]

https://arxiv.org/pdf/gr-qc/0304015.pdf

2007ApJ...655...77G

A Log-Quadratic Relation for Predicting Supermassive Black Hole Masses from the Host Bulge Sérsic Index

2007-01-01

['black hole physics', 'galaxies bulges', 'galaxies fundamental parameters', 'galaxies structure', 'astrophysics']

[]

We reinvestigate the correlation between black hole mass and bulge concentration. With an increased galaxy sample (totaling 27) and updated estimates of galaxy distances, black hole masses, and Sérsic indices n-a measure of concentration-we perform a least-squares regression analysis to obtain a relation suitable for the purpose of predicting black hole masses in other galaxies. In addition to the linear relation, logM<SUB>bh</SUB>=(7.81+/-0.08)+(2.69+/-0.28)log(n/3) with ɛ<SUB>intrinsic</SUB>=0.31<SUP>+0.09</SUP><SUB>-0.07</SUB> dex, we investigated the possibility of a higher order M<SUB>bh</SUB>-n relation, finding the second-order term in the best-fitting quadratic relation to be inconsistent with a value of zero at greater than the 99.99% confidence level. The optimal relation is given by logM<SUB>bh</SUB>=(7.98+/-0.09)+(3.70+/-0.46)log(n/3)-(3.10+/-0.84)[log(n/3)]<SUP>2</SUP>, with ɛ<SUB>intrinsic</SUB>=0.18<SUP>+0.07</SUP><SUB>-0.06</SUB> dex and a total absolute scatter of 0.31 dex. When the quadratic relation is extrapolated, it predicts black holes with masses of ~10<SUP>3</SUP> M<SUB>solar</SUB> in n=0.5 dwarf elliptical galaxies, compared to ~10<SUP>5</SUP> M<SUB>solar</SUB> from the linear relation, and an upper bound on the largest black hole masses in the local universe equal to 1.2<SUP>+2.6</SUP><SUB>-0.4</SUB>×10<SUP>9</SUP> M<SUB>solar</SUB>. In addition, we show that the nuclear star clusters at the centers of low-luminosity elliptical galaxies follow an extrapolation of the same quadratic relation, strengthening suggestions for a possible evolutionary link between supermassive black holes and nuclear star clusters. Moreover, we speculate that the merger of two such nucleated galaxies, accompanied by the merger and runaway collision of their central star clusters, could result in the late-time formation of some supermassive black holes. Finally, we predict the existence of, and provide equations for, an M<SUB>bh</SUB>-μ<SUB>0</SUB> relation, in which μ<SUB>0</SUB> is the (extrapolated) central surface brightness of a bulge.

[]

https://arxiv.org/pdf/astro-ph/0607378.pdf

2010PhRvL.105j1102L

Black Strings, Low Viscosity Fluids, and Violation of Cosmic Censorship

2010-01-01

['-', '-', '-', '-', '-', 'methods numerical', '-', '-']

[]

We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black string segments. These segments are themselves subject to a Gregory-Laflamme instability, resulting in a self-similar cascade, where ever-smaller satellite black holes form connected by ever-thinner string segments. This behavior is akin to satellite formation in low-viscosity fluid streams subject to the Rayleigh-Plateau instability. The simulation results imply that the string segments will reach zero radius in finite asymptotic time, whence the classical space-time terminates in a naked singularity. Since no fine-tuning is required to excite the instability, this constitutes a generic violation of cosmic censorship.

[]

https://arxiv.org/pdf/1006.5960.pdf

2011BASI...39..409B

Black hole transients

2011-01-01

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

[]

Sixteen years of observations of black hole transients with the Rossi X-ray Timing Explorer, complemented by other X-ray observatories and ground-based optical/infrared/radio telescopes have given us a clear view of the complex phenomenology associated with their bright outbursts. This has led to the definition of a small number of spectral/timing states which are separated by marked transitions in observables. The association of these states and their transitions to changes in the radio emission from relativistic radio jets completes the picture and have led to the study of the connection between accretion and ejection. A good number of fundamental questions are still unanswered, but the existing picture provides a good framework on which to base theoretical studies. We discuss the current observational standpoint, with emphasis onto the spectral and timing evolution during outbursts, as well as the prospects for future missions such as ASTROSAT (2012) and LOFT (&gt;2020 if selected).

[]

https://arxiv.org/pdf/1109.3388.pdf

2019PhRvL.122u1301B

Primordial Black Hole Dark Matter: LISA Serendipity

2019-01-01

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

[]

There has recently been renewed interest in the possibility that the dark matter in the Universe consists of primordial black holes (PBHs). Current observational constraints leave only a few PBH mass ranges for this possibility. One of them is around 10<SUP>-12</SUP> M<SUB>⊙</SUB> . If PBHs with this mass are formed due to an enhanced scalar-perturbation amplitude, their formation is inevitably accompanied by the generation of gravitational waves (GWs) with frequency peaked in the mHz range, precisely around the maximum sensitivity of the LISA mission. We show that, if these primordial black holes are the dark matter, LISA will be able to detect the associated GW power spectrum. Although the GW source signal is intrinsically non-Gaussian, the signal measured by LISA is a sum of the signal from a large number of independent sources suppressing the non-Gaussianity at detection to an unobservable level. We also discuss the effect of the GW propagation in the perturbed Universe. PBH dark matter generically leads to a detectable, purely isotropic, Gaussian and unpolarized GW signal, a prediction that is testable with LISA.

[]

https://arxiv.org/pdf/1810.12218.pdf

2020JHEP...01..046A

Kerr black holes as elementary particles

2020-01-01

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

[]

Long ago, Newman and Janis showed that a complex deformation z → z + ia of the Schwarzschild solution produces the Kerr solution. The underlying explanation for this relationship has remained obscure. The complex deformation has an electromagnetic counterpart: by shifting the Coloumb potential, we obtain the EM field of a certain rotating charge distribution which we term √{Kerr}. In this note, we identify the origin of this shift as arising from the exponentiation of spin operators for the recently defined "minimally coupled" three-particle amplitudes of spinning particles coupled to gravity, in the large- spin limit. We demonstrate this by studying the impulse imparted to a test particle in the background of the heavy spinning particle. We first consider the electromagnetic case, where the impulse due to √{Kerr} is reproduced by a charged spinning particle; the shift of the Coloumb potential is matched to the exponentiated spin-factor appearing in the amplitude. The known impulse due to the Kerr black hole is then trivially derived from the gravitationally coupled spinning particle via the double copy.

[]

https://arxiv.org/pdf/1906.10100.pdf

2011PhRvD..84l7503D

Compressibility of rotating black holes

2011-01-01

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

[]

Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of nonpositive cosmological constant. The adiabatic compressibility vanishes for a nonrotating black hole and is maximal in the extremal case—comparable with, but still less than, that of a cold neutron star. A speed of sound v<SUB>s</SUB> is associated with the adiabatic compressibility, which is equal to c for a nonrotating black hole and decreases as the angular momentum is increased. An extremal black hole has v<SUB>s</SUB><SUP>2</SUP>=0.9c<SUP>2</SUP> when the cosmological constant vanishes, and more generally v<SUB>s</SUB> is bounded below by c/2.

[]

https://arxiv.org/pdf/1109.0198.pdf

2006ApJ...653L..25G

Ultraviolet Detection of the Tidal Disruption of a Star by a Supermassive Black Hole

2006-01-01

['galaxies nuclei', 'astronomy uv', 'astrophysics']

[]

A supermassive black hole in the nucleus of a galaxy will be revealed when a star passes close enough to be torn apart by tidal forces and a flare of radiation is emitted by the stream of stellar debris that plunges into the black hole. Since common active galactic nuclei have accreting black holes that can also produce flares, a convincing demonstration that a stellar tidal disruption has occurred generally begins with a ``normal'' galaxy that has no evidence of prior nuclear activity. Here we report a luminous UV flare from an elliptical galaxy at z=0.37 in the Groth field of the GALEX Deep Imaging Survey that has no evidence of a Seyfert nucleus from optical spectroscopy and X-ray imaging obtained during the flare. Multiwavelength data collected at the time of the event, and for 2 years following, allow us to constrain, for the first time, the spectral energy distribution of a candidate tidal disruption flare from optical through X-rays. The luminosity and temperature of the radiation and the decay curve of the flare are in excellent agreement with theoretical predictions for the tidal disruption of a star, and provide the strongest empirical evidence for a stellar disruption event to date.

[]

https://arxiv.org/pdf/astro-ph/0612069.pdf

2006MNRAS.370.1351G

A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries

2006-01-01

['black hole physics', 'black hole physics', '-', 'ism jets and outflows', 'astronomy x rays', 'astrophysics']

[]

Deep observations with the Very Large Array of A0620-00, performed in 2005 August, resulted in the first detection of radio emission from a black hole binary at X-ray luminosities as low as 10<SUP>-8.5</SUP> times the Eddington limit. The measured radio flux density, of 51 +/- 7 μJy at 8.5 GHz, is the lowest reported for an X-ray binary system so far, and is interpreted in terms of partially self-absorbed synchrotron emission from outflowing plasma. Making use of the estimated outer accretion rate of A0620-00 in quiescence, we demonstrate that the outflow kinetic power must be energetically comparable to the total accretion power associated with such rate, if it was to reach the black hole with the standard radiative efficiency of 10 per cent. This favours a model for quiescence in which a radiatively inefficient outflow accounts for a sizable fraction of the missing energy, and, in turn, substantially affects the overall dynamics of the accretion flow. Simultaneous observations in the X-ray band, with Chandra, confirm the validity of a non-linear radio/X-ray correlation for hard state black hole binaries down to low quiescent luminosities, thereby contradicting some theoretical expectations. Taking the mass term into account, the A0620-00 data lie on the extrapolation of the so-called Fundamental Plane of black hole activity, which has thus been extended by more than two orders of magnitude in radio and X-ray luminosity. With the addition of the A0620-00 point, the plane relation provides an empirical proof for the scale invariance of the jet-accretion coupling in accreting black holes over the entire parameter space observable with current instrumentation.

[]

https://arxiv.org/pdf/astro-ph/0605376.pdf

2013MNRAS.433.1607L

Black hole formation in the early Universe

2013-01-01

['methods numerical', 'galaxies formation', 'cosmology theory', 'cosmology early universe', '-']

[]

Supermassive black holes with up to a 10<SUP>9</SUP> M<SUB>⊙</SUB> dwell in the centres of present-day galaxies, and their presence has been confirmed at z ≥ 6. Their formation at such early epochs is still an enigma. Different pathways have been suggested to assemble supermassive black holes in the first billion years after the big bang. Direct collapse has emerged as a highly plausible scenario to form black holes as it provides seed masses of 10<SUP>5</SUP>-10<SUP>6</SUP> M<SUB>⊙</SUB>. Gravitational collapse in atomic cooling haloes with virial temperatures T<SUB>vir</SUB> ≥ 10<SUP>4</SUP> K may lead to the formation of massive seed black holes in the presence of an intense background ultraviolet flux. Turbulence plays a central role in regulating accretion and transporting angular momentum. We present here the highest resolution cosmological large eddy simulations to date which track the evolution of high-density regions on scales of 0.25 au beyond the formation of the first peak, and study the impact of subgrid-scale turbulence. The peak density reached in these simulations is 1.2 × 10<SUP>-8</SUP> g cm<SUP>-3</SUP>. Our findings show that while fragmentation occasionally occurs, it does not prevent the growth of a central massive object resulting from turbulent accretion and occasional mergers. The central object reaches ∼1000 M<SUB>⊙</SUB> within four free-fall times, and we expect further growth up to 10<SUP>6</SUP> M<SUB>⊙</SUB> through accretion in about 1 Myr. The direct collapse model thus provides a viable pathway of forming high-mass black holes at early cosmic times.

[]

https://arxiv.org/pdf/1304.0962.pdf

2016ApJ...824L...8R

Dynamical Formation of the GW150914 Binary Black Hole

2016-01-01

['clusters globular', 'gravitational waves', 'stars black holes', '-']

[]

We explore the possibility that GW150914, the binary black hole (BBH) merger recently detected by Advanced LIGO, was formed by gravitational interactions in the core of a dense star cluster. Using models of globular clusters (GCs) with detailed N-body dynamics and stellar evolution, we show that a typical cluster with a mass of 3× {10}<SUP>5</SUP>{M}<SUB>⊙ </SUB> to 6× {10}<SUP>5</SUP>{M}<SUB>⊙ </SUB> is optimal for forming GW150914-like BBHs that will merge in the local universe. We identify the most likely dynamical processes for forming GW150914 in such a cluster, and we show that the detection of GW150914 is consistent with the masses and merger rates expected for BBHs from GCs. Our results show that dynamical processes provide a significant and well-understood pathway for forming BBH mergers in the local universe. Understanding the contribution of dynamics to the BBH merger problem is a critical step in unlocking the full potential of gravitational-wave astronomy.

[]

https://arxiv.org/pdf/1604.04254.pdf

2018JCAP...03..043C

Constraining the mass of dark photons and axion-like particles through black-hole superradiance

2018-01-01

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

[]

Ultralight bosons and axion-like particles appear naturally in different scenarios and could solve some long-standing puzzles. Their detection is challenging, and all direct methods hinge on unknown couplings to the Standard Model of particle physics. However, the universal coupling to gravity provides model-independent signatures for these fields. We explore here the superradiant instability of spinning black holes triggered in the presence of such fields. The instability taps angular momentum from and limits the maximum spin of astrophysical black holes. We compute, for the first time, the spectrum of the most unstable modes of a massive vector (Proca) field for generic black-hole spin and Proca mass. The observed stability of the inner disk of stellar-mass black holes can be used to derive direct constraints on the mass of dark photons in the mass range 10<SUP>-13</SUP> eVlesssim m<SUB>V</SUB> lesssim 3× 10<SUP>-12</SUP> eV. By including also higher azimuthal modes, similar constraints apply to axion-like particles in the mass range 6×10<SUP>-13</SUP> eVlesssim m<SUB>ALP</SUB> lesssim 10<SUP>-11</SUP> eV. Likewise, mass and spin distributions of supermassive BHs—as measured through continuum fitting, Kα iron line, or with the future space-based gravitational-wave detector LISA - imply indirect bounds in the mass range approximately 10<SUP>-19</SUP> eVlesssim m<SUB>V</SUB>, m<SUB>ALP</SUB> lesssim 10<SUP>-13</SUP> eV, for both axion-like particles and dark photons. Overall, superradiance allows to explore a region of approximately 8 orders of magnitude in the mass of ultralight bosons.

[]

https://arxiv.org/pdf/1801.01420.pdf

2019ApJ...880...67J

Super-Eddington Accretion Disks around Supermassive Black Holes

2019-01-01

['accretion', 'accretion disks', 'mhd', 'methods numerical', 'galaxies quasars', 'radiative transfer', '-']

[]

We use global three-dimensional radiation magnetohydrodynamical simulations to study accretion disks onto a 5× {10}<SUP>8</SUP>{M}<SUB>⊙ </SUB> black hole with accretion rates varying from ∼ 250{L}<SUB>Edd</SUB>}/{c}<SUP>2</SUP> to 520{L}<SUB>Edd</SUB>}/{c}<SUP>2</SUP>. We initialize the disks with a weakly magnetized torus centered at either 50 or 80 gravitational radii, leading to self-consistent turbulence generated by the magnetorotational instability (MRI). The inner regions of all disks have radiation pressure ∼10<SUP>4</SUP>-10<SUP>6</SUP> times the gas pressure. Nonaxisymmetric density waves that steepen into spiral shocks form as gas flows toward the black hole. Maxwell stress from MRI turbulence can be larger than the Reynolds stress only when the net vertical magnetic flux is sufficiently large. Outflows are formed with a speed of ∼0.1-0.4c. When the accretion rate is smaller than ∼ 500{L}<SUB>Edd</SUB>}/{c}<SUP>2</SUP>, outflows are launched from ∼10 gravitational radii, and the radiative efficiency is ∼5%-7%. For an accretion rate reaching 1500{L}<SUB>Edd</SUB>}/{c}<SUP>2</SUP>, most of the funnel region near the rotation axis becomes optically thick, and the outflow is launched from beyond 50 gravitational radii. The radiative efficiency is reduced to 1%. We always find that the kinetic energy luminosity associated with the outflow is at most ∼15%-30% of the radiative luminosity. The mass flux in the outflow is ∼15%-50% of the net mass accretion rates. We discuss the implications of our simulation results on the observational properties of these disks.

[]

https://arxiv.org/pdf/1709.02845.pdf

2014Natur.514..198M

A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source

2014-01-01

['-']

[]

Most ultraluminous X-ray sources have a typical set of properties not seen in Galactic stellar-mass black holes. They have luminosities of more than 3 × 10<SUP>39</SUP> ergs per second, unusually soft X-ray components (with a typical temperature of less than about 0.3 kiloelectronvolts) and a characteristic downturn in their spectra above about 5 kiloelectronvolts. Such puzzling properties have been interpreted either as evidence of intermediate-mass black holes or as emission from stellar-mass black holes accreting above their Eddington limit, analogous to some Galactic black holes at peak luminosity. Recently, a very soft X-ray spectrum was observed in a rare and transient stellar-mass black hole. Here we report that the X-ray source P13 in the galaxy NGC 7793 is in a binary system with a period of about 64 days and exhibits all three canonical properties of ultraluminous sources. By modelling the strong optical and ultraviolet modulations arising from X-ray heating of the B9Ia donor star, we constrain the black hole mass to be less than 15 solar masses. Our results demonstrate that in P13, soft thermal emission and spectral curvature are indeed signatures of supercritical accretion. By analogy, ultraluminous X-ray sources with similar X-ray spectra and luminosities of up to a few times 10<SUP>40</SUP> ergs per second can be explained by supercritical accretion onto massive stellar-mass black holes.

[]

https://arxiv.org/pdf/1410.4250.pdf

2015ApJ...809L..14B

A ∼50,000 M<SUB>⊙</SUB> Solar Mass Black Hole in the Nucleus of RGG 118

2015-01-01

['galaxies active', 'galaxies dwarf', 'galaxies quasars', '-']

[]

Scaling relations between black hole (BH) masses and their host galaxy properties have been studied extensively over the last two decades, and point toward co-evolution of central massive BHs and their hosts. However, these relations remain poorly constrained for BH masses below ∼ {10}<SUP>6</SUP> {M}<SUB>⊙ </SUB>. Here we present optical and X-ray observations of the dwarf galaxy RGG 118 taken with the Magellan Echellette Spectrograph on the 6.5 m Clay Telescope and Chandra X-ray Observatory. Based on Sloan Digital Sky Survey spectroscopy, RGG 118 was identified as possessing narrow emission line ratios indicative of photoionization partly due to an active galactic nucleus. Our higher resolution spectroscopy clearly reveals broad Hα emission in the spectrum of RGG 118. Using virial BH mass estimate techniques, we calculate a BH mass of ∼50,000 {M}<SUB>⊙ </SUB>. We detect a nuclear X-ray point source in RGG 118, suggesting a total accretion powered luminosity of L=4× {10}<SUP>40</SUP> {erg} {{{s}}}<SUP>-1</SUP>, and an Eddington fraction of ∼1%. The BH in RGG 118 is the smallest ever reported in a galaxy nucleus and we find that it lies on the extrapolation of the {M}<SUB>{BH</SUB>}-{σ }<SUB>*</SUB> relation to the lowest masses yet.

[]

https://arxiv.org/pdf/1506.07531.pdf

2009PhLB..670..449S

Non-commutative geometry inspired higher-dimensional charged black holes

2009-01-01

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

[]

We obtain a new, exact, solution of the Einstein's equation in higher dimensions. The source is given by a static spherically symmetric, Gaussian distribution of mass and charge. The resulting metric describes a regular, i.e. curvature singularity free, charged black hole in higher dimensions. The metric smoothly interpolates between Reissner-Nordström geometry at large distance, and de Sitter spacetime at short distance. Thermodynamical properties of the black hole are investigated and the form of the Area Law is determined. We study pair creation and show that the upper bound on the discharge time increases with the number of extra dimensions.

[]

https://arxiv.org/pdf/0801.3519.pdf

2009JHEP...03..070D

Black holes in asymptotically Lifshitz spacetime

2009-01-01

['-']

[]

A model of 3+1 dimensional gravity with negative cosmological constant coupled to abelian gauge fields has been proposed as a gravity dual for Lifshitz like critical phenomena in 2+1 dimensions. The finite temperature behavior is described by black holes that are asymptotic to the Lifshitz fixed point geometry. There is a one-parameter family of charged black holes, where the magnitude of the charge is uniquely determined by the black hole area. These black holes are thermodynamically stable and become extremal in the limit of vanishing size. The theory also has a discrete spectrum of localized objects described by non-singular spacetime geometries. The finite temperature behavior of Wilson loops is reminiscent of strongly coupled gauge theories in 3+1 dimensions, including screening at large distances.

[]

https://arxiv.org/pdf/0812.5088.pdf

2009ApJ...695..404R

Tidal Disruption and Ignition of White Dwarfs by Moderately Massive Black Holes

2009-01-01

['accretion', 'accretion disks', 'black hole physics', 'clusters globular', 'hydrodynamics', 'nuclear reactions;nucleosynthesis;abundances', 'nuclear reactions;nucleosynthesis;abundances', 'nuclear reactions;nucleosynthesis;abundances', 'astrophysics']

[]

We present a numerical investigation of the tidal disruption of white dwarfs by moderately massive black holes, with particular reference to the centers of dwarf galaxies and globular clusters. Special attention is given to the fate of white dwarfs of all masses that approach the black hole close enough to be disrupted and severely compressed to such an extent that explosive nuclear burning can be triggered. Consistent modeling of the gas dynamics together with the nuclear reactions allows for a realistic determination of the explosive energy release. In the most favorable cases, the nuclear energy release may be comparable to that of typical Type Ia supernovae. Although the explosion will increase the mass fraction escaping on hyperbolic orbits, a good fraction of the debris remains to be swallowed by the hole, causing a bright soft X-ray flare lasting for about a year. Such transient signatures, if detected, would be a compelling testimony for the presence of a moderately massive black hole (below 10<SUP>5</SUP> M <SUB>sun</SUB>).

[]

https://arxiv.org/pdf/0808.2143.pdf

2014ApJ...781...45A

Black Hole Triple Dynamics: A Breakdown of the Orbit Average Approximation and Implications for Gravitational Wave Detections

2014-01-01

['stars binaries close', 'clusters globular', 'gravitational waves', 'stars kinematics and dynamics', '-', '-']

[]

Coalescing black hole (BH) binaries forming in the dense core of globular clusters (GCs) are expected to be one of the brightest sources of gravitational wave (GW) radiation for the next generation of ground-based laser interferometers. Favorable conditions for a merger are initiated by the Kozai resonance in which the gravitational interaction with a third distant object, typically another BH, induces quasi-periodic variations of the inner BH binary eccentricity. In this article we perform high precision three-body simulations of the long-term evolution of hierarchical BH triples and investigate the conditions that lead to the merging of the BH binary and the way it might become an observable source of GW radiation. We find that the secular orbit average treatment, which was adopted in previous works, does not reliably describe the dynamics of these systems if the binary is orbited by the outer BH on a highly inclined orbit at a moderate distance. We show that 50% of coalescing BH binaries driven by the Kozai mechanism in GCs will have eccentricities larger than 0.1, with 10% of them being extremely eccentric, (1 - e) &lt;~ 10<SUP>-4</SUP>, when they first chirp in the frequency band of ground-based laser interferometers. This implies that a large fraction of such GW sources could be missed if conventional quasi-circular templates are used for analysis of GW detector data. The efficient detection of all coalescing BH binaries in GCs will therefore require template banks of eccentric inspiral waveforms for matched-filtering and dedicated search strategies.

[]

https://arxiv.org/pdf/1308.3674.pdf

2012PhRvD..86j4017P

Perturbations of slowly rotating black holes: Massive vector fields in the Kerr metric

2012-01-01

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

[]

We discuss a general method to study linear perturbations of slowly rotating black holes which is valid for any perturbation field, and particularly advantageous when the field equations are not separable. As an illustration of the method we investigate massive vector (Proca) perturbations in the Kerr metric, which do not appear to be separable in the standard Teukolsky formalism. Working in a perturbative scheme, we discuss two important effects induced by rotation: a Zeeman-like shift of nonaxisymmetric quasinormal modes and bound states with different azimuthal number m, and the coupling between axial and polar modes with different multipolar index ℓ. We explicitly compute the perturbation equations up to second order in rotation, but in principle the method can be extended to any order. Working at first order in rotation we show that polar and axial Proca modes can be computed by solving two decoupled sets of equations, and we derive a single master equation describing axial perturbations of spin s=0 and s=±1. By extending the calculation to second order we can study the superradiant regime of Proca perturbations in a self-consistent way. For the first time we show that Proca fields around Kerr black holes exhibit a superradiant instability, which is significantly stronger than for massive scalar fields. Because of this instability, astrophysical observations of spinning black holes provide the tightest upper limit on the mass of the photon: m<SUB>γ</SUB>≲4×10<SUP>-20</SUP>eV under our most conservative assumptions. Spin measurements for the largest black holes could reduce this bound to m<SUB>γ</SUB>≲10<SUP>-22</SUP>eV or lower.

[]

https://arxiv.org/pdf/1209.0773.pdf

2011JHEP...05..022G

Higher spin black holes

2011-01-01

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

[]

We study classical solutions of three dimensional higher spin gravity in the Chern-Simons formulation. We find solutions that generalize the BTZ black hole and carry spin-3 charge. The black hole entropy formula yields a result for the asymptotic growth of the partition function at finite spin-3 chemical potential. Along the way, we develop technology for computing AdS/CFT correlation functions involving higher spin operators.

[]

https://arxiv.org/pdf/1103.4304.pdf

2015ApJ...806...22D

Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IV. Hβ Time Lags and Implications for Super-Eddington Accretion

2015-01-01

['accretion', 'accretion disks', 'black hole physics', 'galaxies active', 'galaxies quasars', '-', '-', '-']

[]

We have completed two years of photometric and spectroscopic monitoring of a large number of active galactic nuclei (AGNs) with very high accretion rates. In this paper, we report on the result of the second phase of the campaign, during 2013-2014, and the measurements of five new Hβ time lags out of eight monitored AGNs. All five objects were identified as super-Eddington accreting massive black holes (SEAMBHs). The highest measured accretion rates for the objects in this campaign are \mathscr{\dot{M}} {\mkern 1mu} ≳ 200, where \mathscr{\dot{M}} {\mkern 1mu} ={{\dot{M}}<SUB>\bullet </SUB>}/{{L}<SUB>Edd</SUB>}{{c}<SUP>-2</SUP>}, {{\dot{M}}<SUB>\bullet </SUB>} is the mass accretion rates, {{L}<SUB>Edd</SUB>} is the Eddington luminosity and c is the speed of light. We find that the Hβ time lags in SEAMBHs are significantly shorter than those measured in sub-Eddington AGNs, and the deviations increase with increasing accretion rates. Thus, the relationship between broad-line region size ({{R}<SUB>_{Hβ </SUB>}}) and optical luminosity at 5100 Å, {{R}<SUB>_{Hβ </SUB>}}-{{L}<SUB>5100</SUB>}, requires accretion rate as an additional parameter. We propose that much of the effect may be due to the strong anisotropy of the emitted slim-disk radiation. Scaling {{R}<SUB>_{Hβ </SUB>}} by the gravitational radius of the black hole (BH), we define a new radius-mass parameter (Y) and show that it saturates at a critical accretion rate of \mathscr{\dot{M}} {\mkern 1mu} {{}<SUB>c</SUB>}=6∼ 30, indicating a transition from thin to slim accretion disk and a saturated luminosity of the slim disks. The parameter Y is a very useful probe for understanding the various types of accretion onto massive BHs. We briefly comment on implications to the general population of super-Eddington AGNs in the universe and applications to cosmology.

[]

https://arxiv.org/pdf/1504.01844.pdf

2003PhRvD..67h4020C

Quasinormal modes of the near extremal Schwarzschild de Sitter black hole

2003-01-01

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

[]

We present an exact expression for the quasinormal modes of scalar, electromagnetic, and gravitational perturbations of a near extremal Schwarzschild de Sitter black hole and we show that is why a previous approximation holds exactly in this near extremal regime. In particular, our results give the asymptotic behavior of the quasinormal frequencies for highly damped modes, which has recently attracted much attention due to the proposed identification of its real part with the Barbero-Immirzi parameter.

[]

https://arxiv.org/pdf/gr-qc/0301078.pdf

2009PhLB..679..504C

Thermodynamics of black holes in Hořava-Lifshitz gravity

2009-01-01

['-', '-']

[]

By using the canonical Hamiltonian method, we obtain the mass and entropy of the black holes with general dynamical coupling constant λ in Hořava-Lifshitz Gravity. Regardless of whether the horizon is sphere, plane or hyperboloid, we find these black holes are thermodynamically stable in some parameter space and unstable phase also exists in other parameter space. The relation between the entropy and horizon area of the black holes has an additional coefficient depending on the coupling constant λ, compared to the λ = 1 case. For λ = 1, the well-known coefficient of one quarter is recovered in the infrared region.

[]

https://arxiv.org/pdf/0905.0751.pdf

2004ApJ...606..788M

Chaotic Loss Cones and Black Hole Fueling

2004-01-01

['black hole physics', 'galaxies elliptical lenticular;cd', 'cd', 'galaxies nuclei', 'galaxies structure', 'stars kinematics and dynamics', 'astrophysics']

[]

In classical loss cone theory, stars are supplied to a central black hole via gravitational scattering onto low angular momentum orbits. Higher feeding rates are possible if the gravitational potential near the black hole is nonaxisymmetric and the orbits are chaotic. Motivated by recently published, self-consistent models, we evaluate rates of stellar capture and disruption in triaxial nuclei. Rates are found to substantially exceed those in collisionally resupplied loss cones, as long as an appreciable fraction of the orbits are centrophilic. The mass captured by a black hole after a given time in a steep (ρ~r<SUP>-2</SUP>) nucleus scales as σ<SUP>5</SUP> with σ the stellar velocity dispersion, and the accumulated mass in 10<SUP>10</SUP> yr is of the correct order to reproduce the M<SUB>•</SUB>-σ relation. Triaxiality can solve the ``final parsec problem'' of decaying black hole binaries by increasing the flux of stars into the binary's loss cone.

[]

https://arxiv.org/pdf/astro-ph/0302296.pdf

2018PhRvD..97h4037A

Black-hole solutions with scalar hair in Einstein-scalar-Gauss-Bonnet theories

2018-01-01

['-', '-']

[]

In the context of the Einstein-scalar-Gauss-Bonnet theory, with a general coupling function between the scalar field and the quadratic Gauss-Bonnet term, we investigate the existence of regular black-hole solutions with scalar hair. Based on a previous theoretical analysis, which studied the evasion of the old and novel no-hair theorems, we consider a variety of forms for the coupling function (exponential, even and odd polynomial, inverse polynomial, and logarithmic) that, in conjunction with the profile of the scalar field, satisfy a basic constraint. Our numerical analysis then always leads to families of regular, asymptotically flat black-hole solutions with nontrivial scalar hair. The solution for the scalar field and the profile of the corresponding energy-momentum tensor, depending on the value of the coupling constant, may exhibit a nonmonotonic behavior, an unusual feature that highlights the limitations of the existing no-hair theorems. We also determine and study in detail the scalar charge, horizon area, and entropy of our solutions.

[]

https://arxiv.org/pdf/1711.07431.pdf

2017MNRAS.468.3935H

Blossoms from black hole seeds: properties and early growth regulated by supernova feedback

2017-01-01

['black hole physics', 'methods numerical', 'galaxies evolution', 'galaxies formation', 'galaxies photometry', '-']

[]

Massive black holes (BHs) inhabit local galaxies, including the Milky Way and some dwarf galaxies. BH formation, occurring at early cosmic times, must account for the properties of BHs in today's galaxies, notably why some galaxies host a BH, and others do not. We investigate the formation, distribution and growth of BH 'seeds' by using the adaptive mesh refinement code ramses. We develop an implementation of BH formation in dense, low-metallicity environments, as advocated by models invoking the collapse of the first generation of stars, or of dense nuclear star clusters. The seed masses are computed one-by-one on-the-fly, based on the star formation rate and the stellar initial mass function. This self-consistent method to seed BHs allows us to study the distribution of BHs in a cosmological context and their evolution over cosmic time. We find that all high-mass galaxies tend to host a BH, whereas low-mass counterparts have a lower probability of hosting a BH. After the end of the epoch of BH formation, this probability is modulated by the growth of the galaxy. The simulated BHs connect to low-redshift observational samples, and span a similar range in accretion properties as Lyman-break analogs. The growth of BHs in low-mass galaxies is stunted by strong supernova (SN) feedback. The properties of BHs in dwarf galaxies thus remain a testbed for BH formation. Simulations with strong SN feedback, which is able to quench BH accretion in shallow potential wells, produce galaxies and BHs in better agreement with observational constraints.

[]

https://arxiv.org/pdf/1605.09394.pdf

2011MNRAS.415.2323I

A physical model for the continuum variability and quasi-periodic oscillation in accreting black holes

2011-01-01

['accretion', 'accretion disks', 'astronomy x rays', 'astronomy x rays', '-']

[]

The power spectra of black hole binaries have been well studied for decades, giving a very detailed phenomenological picture of the variability properties and their correlation with the energy spectrum (spectral state) of the source. Here we take the truncated disc/hot inner flow picture which can describe the spectral changes, and show that propagating mass accretion rate fluctuations in the hot flow can match the broad-band power spectral properties seen in black hole binaries, i.e. give an approximately band-limited noise between a low- and a high-frequency break. The low-frequency break marks the viscous time-scale at the outer edge of the hot inner flow, which is the inner edge of the truncated disc. The fluctuations in mass accretion rate propagate towards the central object in a finite time meaning the high-frequency break is more complex than simply the viscous time-scale at the inner edge of the hot flow because fluctuations on time-scales shorter than the propagation time are incoherent. The model also predicts the Lense-Thirring precession time-scale of the hot flow, as this is set by the combination of inner and outer radius of the flow, together with its surface density which is self-consistently calculated from the propagating fluctuations. We show that this naturally gives the observed relation between the low-frequency break and quasi-periodic oscillation (QPO) frequency as the outer radius of the flow moves inwards, and that this model predicts many of the observed QPO properties such as correlation of coherence with frequency, and of the recently discovered correlation of frequency with flux on short time-scales. <P />We fit this total model of the variability to a sequence of five observed power spectra from the bright black hole binary XTE J1550-564 as the source transitioned from a low/hard to very high state. This is the first time that a power spectrum from a black hole binary has been fit with a physical model for the variability. The data are well fit if the inner radius of the flow remains constant, while the outer radius sweeps inwards from ∼75 to 12 gravitational radii. This range of radii is the same range as required by models of the energy spectral evolution, giving the first self-consistent description of the evolution of both the spectrum and variability of black hole binaries.

[]

https://arxiv.org/pdf/1101.2336.pdf

2016ApJ...827L..31Z

Mergers of Charged Black Holes: Gravitational-wave Events, Short Gamma-Ray Bursts, and Fast Radio Bursts

2016-01-01

['radiation', 'stars black holes', '-', '-']

[]

The discoveries of GW150914, GW151226, and LVT151012 suggest that double black hole (BH-BH) mergers are common in the universe. If at least one of the two merging black holes (BHs) carries a certain amount of charge, possibly retained by a rotating magnetosphere, the inspiral of a BH-BH system would drive a global magnetic dipole normal to the orbital plane. The rapidly evolving magnetic moment during the merging process would drive a Poynting flux with an increasing wind power. The magnetospheric activities during the final phase of the merger would make a fast radio burst (FRB) if the BH charge can be as large as a factor of \hat{q}∼ ({10}<SUP>-9</SUP>{--}{10}<SUP>-8</SUP>) of the critical charge Q <SUB> c </SUB> of the BH. At large radii, dissipation of the Poynting flux energy in the outflow would power a short-duration high-energy transient, which would appear as a detectable short-duration gamma-ray burst (GRB) if the charge can be as large as \hat{q}∼ ({10}<SUP>-5</SUP>{--}{10}<SUP>-4</SUP>). The putative short GRB coincident with GW150914 recorded by Fermi GBM may be interpreted with this model. Future joint GW/GRB/FRB searches would lead to a measurement or place a constraint on the charges carried by isolate BHs.

[]

https://arxiv.org/pdf/1602.04542.pdf

2021JHEP...02..048M

Classical black hole scattering from a worldline quantum field theory

2021-01-01

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

[]

A precise link is derived between scalar-graviton S-matrix elements and expectation values of operators in a worldline quantum field theory (WQFT), both used to describe classical scattering of black holes. The link is formally provided by a worldline path integral representation of the graviton-dressed scalar propagator, which may be inserted into a traditional definition of the S-matrix in terms of time-ordered correlators. To calculate expectation values in the WQFT a new set of Feynman rules is introduced which treats the gravitational field h<SUB>μν</SUB>(x) and position x<SUB>i</SUB><SUP>μ</SUP>(τ<SUB>i</SUB>) of each black hole on equal footing. Using these both the 3PM three-body gravitational radiation &lt;h<SUP>μv</SUP>(k)&gt; and 2PM two-body deflection Δ p<SUB>i</SUB><SUP>μ</SUP> from classical black hole scattering events are obtained. The latter can also be obtained from the eikonal phase of a 2 → 2 scalar S-matrix, which we show corresponds to the free energy of the WQFT.

[]

https://arxiv.org/pdf/2010.02865.pdf

2012Sci...338.1445N

A Universal Scaling for the Energetics of Relativistic Jets from Black Hole Systems

2012-01-01

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

[]

Black holes generate collimated, relativistic jets, which have been observed in gamma-ray bursts (GRBs), microquasars, and at the center of some galaxies [active galactic nuclei (AGN)]. How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGN is still unknown. Here, we show that jets produced by AGN and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the gamma-ray luminosity, with AGN and GRBs lying at the low- and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.

[]

https://arxiv.org/pdf/1212.3343.pdf

1993PhRvL..71.2367S

String theory and the principle of black hole complementarity

1993-01-01

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

[]

String theory provides an example of the kind of apparent inconsistency that the principle of black hole complementarity deals with. To a freely infalling observer a string falling through a black hole horizon appears to be a Planck size object. To an outside observer the string and all the information it carries begin to spread as the string approache the horizon. In a time of order the ``information retention time'' it fills the entire area of the horizon.

[]

https://arxiv.org/pdf/hep-th/9307168.pdf

1997PhRvD..56.6166G

Constraints on the density perturbation spectrum from primordial black holes

1997-01-01

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

[]

We reexamine the constraints on the density perturbation spectrum, including its spectral index n, from the production of primordial black holes. The standard cosmology, where the Universe is radiation dominated from the end of inflation up until the recent past, was studied by Carr, Gilbert, and Lidsey; we correct two errors in their derivation and find a significantly stronger constraint than they did: n&lt;~1.25 rather than their 1.5. We then consider an alternative cosmology in which a second period of inflation, known as thermal inflation and designed to solve additional relic overdensity problems, occurs at a lower-energy scale than the main inflationary period. In that case, the constraint weakens to n&lt;~1.3, and thermal inflation also leads to a ``missing mass'' range 10<SUP>18</SUP> g&lt;~M&lt;~10<SUP>26</SUP> g in which primordial black holes cannot form. Finally, we discuss the effect of allowing for the expected non-Gaussianity in the density perturbations predicted by Bullock and Primack, which can weaken the constraints further by up to 0.05.

[]

https://arxiv.org/pdf/astro-ph/9704251.pdf

1995NuPhB.454..379R

The rotating dyonic black holes of Kaluza-Klein theory

1995-01-01

['-', '-']

[]

The most general electrically and magnetically charged rotating black hole solutions of 5 dimensional Kaluza-Klein theory are given in an explicit form. Various classical quantities associated with the black holes are derived. In particular, one finds the very surprising result that the gyromagnetic and gyroelectric ratios can become arbitrarily large. The thermodynamic quantities of the black holes are calculated and a Smarr-type formula is obtained leading to a generalized first law of black hole thermodynamics. The properties of the extreme solutions are investigated and it is shown how they naturally separate into two classes. The extreme solutions in one class are found to have two unusual properties: (i) Their event horizons have zero angular velocity and yet they have non-zero ADM angular momentum. (ii) In certain circumstances it is possible to add angular momentum to these extreme solutions without changing the mass or charges and yet still maintain an extreme solution. Regarding the extreme black holes as elementary particles, their stability is discussed and it is found that they are stable provided they have sufficient angular momentum.

[]

https://arxiv.org/pdf/hep-th/9505038.pdf

2013PhRvD..87d4057A

Shadow of a Kaluza-Klein rotating dilaton black hole

2013-01-01

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

[]

We study the shadow produced by a spinning Kaluza-Klein black hole in Einstein gravity coupled to a Maxwell field and a dilaton. The size and the shape of the shadow depend on the mass, the charge, and the angular momentum. We find that, for fixed values of these parameters, the shadow is slightly larger and less deformed than for its Kerr-Newman counterpart.

[]

https://arxiv.org/pdf/1301.0532.pdf

2014JCAP...01..023D

Quantum compositeness of gravity: black holes, AdS and inflation

2014-01-01

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

[]

Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem.

[]

https://arxiv.org/pdf/1312.4795.pdf

2010RvMP...82.3069C

Black-hole binaries, gravitational waves, and numerical relativity

2010-01-01

['-', '-', '-', '-', 'methods numerical', '-', '-', '-', '-', '-', '-']

[]

Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events, releasing tremendous amounts of energy in the form of gravitational radiation, and are key sources for both ground- and space-based gravitational-wave detectors. The black-hole merger dynamics and the resulting gravitational wave forms can only be calculated through numerical simulations of Einstein’s equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit could be simulated. Recently, however, a series of dramatic advances in numerical relativity has allowed stable, robust black-hole merger simulations. This remarkable progress in the rapidly maturing field of numerical relativity and the new understanding of black-hole binary dynamics that is emerging is chronicled. Important applications of these fundamental physics results to astrophysics, to gravitational-wave astronomy, and in other areas are also discussed.

[]

https://arxiv.org/pdf/1010.5260.pdf

2012MNRAS.419.2497B

On the correlations between galaxy properties and supermassive black hole mass

2012-01-01

['black hole physics', 'galaxies fundamental parameters', 'galaxies kinematics and dynamics', 'galaxies photometry', 'galaxies statistics', '-']

[]

We use a large sample of upper limits and accurate estimates of supermassive black hole (SMBH) masses coupled with libraries of host galaxy velocity dispersions, rotational velocities and photometric parameters extracted from Sloan Digital Sky Survey i-band images to establish correlations between the SMBH and host galaxy parameters. We test whether the mass of the black hole, M<SUB>•</SUB>, is fundamentally driven by either local or global galaxy properties. We explore correlations between M<SUB>•</SUB> and stellar velocity dispersion σ<SUB>e</SUB>, i-band bulge luminosity L<SUB>i, bulge</SUB>, bulge mass M<SUB>bulge</SUB>, bulge Sérsic index n, bulge mean effective surface brightness &lt;μ<SUB>e, bulge</SUB>&gt;, i-band luminosity of the galaxy L<SUB>i, gal</SUB>, galaxy stellar mass ?, maximum circular velocity V<SUB>c</SUB>, and galaxy dynamical and effective masses M<SUB>dyn, gal</SUB> and M<SUB>e, gal</SUB>. We verify the tightness of the M<SUB>•</SUB>-σ<SUB>e</SUB> relation and find that correlations with other galaxy parameters do not yield tighter trends. We do not find differences in the M<SUB>•</SUB>-σ<SUB>e</SUB> relation of barred and unbarred galaxies. The M<SUB>•</SUB>-σ<SUB>e</SUB> relation of pseudo-bulges is also coarser and has a different slope than that involving classical bulges. The M<SUB>•</SUB>-M<SUB>bulge</SUB> is not as tight as the M<SUB>•</SUB>-σ<SUB>e</SUB> relation, despite the bulge mass proving to be a better proxy of M<SUB>•</SUB> than bulge luminosity, and despite adding the bulge effective radius as an additional fitting parameter. Contrary to various published reports, we find a rather poor correlation between M<SUB>•</SUB> and n (or &lt;μ<SUB>e, bulge</SUB>&gt;), suggesting that M<SUB>•</SUB> is not related to the bulge light concentration. The correlations between M<SUB>•</SUB> and galaxy luminosity or mass are not a marked improvement over the M<SUB>•</SUB>-σ<SUB>e</SUB> relation. These scaling relations depend sensitively on the host galaxy morphology: early-type galaxies follow a tighter relation than late-type galaxies. If V<SUB>c</SUB> is a proxy for the dark matter halo mass, the large scatter of the M<SUB>•</SUB>-V<SUB>c</SUB> relation then suggests that M<SUB>•</SUB> is more coupled to the baryonic rather than the dark matter. We have tested the need for a third parameter in the M<SUB>•</SUB> scaling relations, through various linear correlations with bulge and galaxy parameters, only to confirm that the Fundamental Plane of the SMBH is mainly driven by σ<SUB>e</SUB> with a small tilt due to the effective radius. We provide a compendium of galaxy structural properties for most of the SMBH hosts known to date.

[]

https://arxiv.org/pdf/1109.6265.pdf

2017ComAC...4....1P

The black hole accretion code

2017-01-01

['-', '-']

[]

We present the black hole accretion code ( BHAC), a new multidimensional general-relativistic magnetohydrodynamics module for the MPI-AMRVAC framework. BHAC has been designed to solve the equations of ideal general-relativistic magnetohydrodynamics in arbitrary spacetimes and exploits adaptive mesh refinement techniques with an efficient block-based approach. Several spacetimes have already been implemented and tested. We demonstrate the validity of BHAC by means of various one-, two-, and three-dimensional test problems, as well as through a close comparison with the HARM3D code in the case of a torus accreting onto a black hole. The convergence of a turbulent accretion scenario is investigated with several diagnostics and we find accretion rates and horizon-penetrating fluxes to be convergent to within a few percent when the problem is run in three dimensions. Our analysis also involves the study of the corresponding thermal synchrotron emission, which is performed by means of a new general-relativistic radiative transfer code, BHOSS. The resulting synthetic intensity maps of accretion onto black holes are found to be convergent with increasing resolution and are anticipated to play a crucial role in the interpretation of horizon-scale images resulting from upcoming radio observations of the source at the Galactic Center.

[]

https://arxiv.org/pdf/1611.09720.pdf

2016ApJ...819L..17B

Migration Traps in Disks around Supermassive Black Holes

2016-01-01

['accretion', 'accretion disks', 'black hole physics', 'galaxies nuclei', '-', '-', '-']

[]

Accretion disks around supermassive black holes (SMBHs) in active galactic nuclei (AGNs) contain stars, stellar mass black holes, and other stellar remnants, which perturb the disk gas gravitationally. The resulting density perturbations exert torques on the embedded masses causing them to migrate through the disk in a manner analogous to planets in protoplanetary disks. We determine the strength and direction of these torques using an empirical analytic description dependent on local disk gradients, applied to two different analytic, steady-state disk models of SMBH accretion disks. We find that there are radii in such disks where the gas torque changes sign, trapping migrating objects. Our analysis shows that major migration traps generally occur where the disk surface density gradient changes sign from positive to negative, around 20-300R<SUB>g</SUB>, where R<SUB>g</SUB> = 2GM/c<SUP>2</SUP> is the Schwarzschild radius. At these traps, massive objects in the AGN disk can accumulate, collide, scatter, and accrete. Intermediate mass black hole formation is likely in these disk locations, which may lead to preferential gap and cavity creation at these radii. Our model thus has significant implications for SMBH growth as well as gravitational wave source populations.

[]

https://arxiv.org/pdf/1511.00005.pdf

1994PhRvD..49.6606S

Strings, black holes, and Lorentz contraction

1994-01-01

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

[]

Consistency of quantum mechanics in black hole physics requires unusual Lorentz transformation properties of the size and shape of physical systems with momentum beyond the Planck scale. A simple parton model illustrates the kind of behavior which is needed. It is then shown that conventional fundamental string theory shares these features.

[]

https://arxiv.org/pdf/hep-th/9308139.pdf

1997ApJ...489..791M

Spectrum of Optically Thin Advection-dominated Accretion Flow around a Black Hole: Application to Sagittarius A*

1997-01-01

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

[]

The global structure of optically thin advection-dominated accretion flows composed of two-temperature plasma around black holes is calculated. We adopt the full set of basic equations, including the advective energy transport in the energy equation for the electrons. The spectra emitted by the optically thin accretion flows are also investigated. The radiation mechanisms that are taken into account are bremsstrahlung, synchrotron emission, and Comptonization. The calculation of the spectra and that of the structure of the accretion flows are made to be completely consistent by calculating the radiative cooling rate at each radius. As a result of the advection domination for the ions, the heat transport from the ions to the electrons becomes practically zero, and the radiative cooling balances with the advective heating in the energy equation of the electrons. Following up on the successful work of Narayan et al., we applied our model to the spectrum of Sgr A*. We find that the spectrum of Sgr A* is explained by the optically thin advection-dominated accretion flow around a black hole of mass M<SUB>BH</SUB> = 10<SUP>6</SUP> M<SUB>⊙</SUB>. The parameter dependence of the spectrum and the structure of the accretion flows is also discussed.

[]

https://arxiv.org/pdf/astro-ph/9708234.pdf

1997MNRAS.292L..21P

The nature of spectral transitions in accreting black holes: the case of CYG X-1

1997-01-01

['accretion disks', 'black hole physics', 'stars fundamental parameters', 'astronomy x rays', 'stars luminosity function;mass function', 'astronomy gamma rays', 'transition', '-', 'accretion', 'accretion disks', 'radiation', '-', 'gamma rays', 'astronomy x rays', 'astronomy x rays', 'astrophysics']

[]

Accreting black holes radiate in one of several spectral states, switching from one to another for reasons that are as yet not understood. Using the best-studied example, Cyg X-1, we identify the geometry and physical conditions characterizing these states. In particular, we show that in the hard state most of the accretion energy is dissipated in a corona-like structure which fills the inner few tens of gravitational radii around the black hole and has Compton optical depth of order unity. In this state, an optically thick accretion disc extends out to greater distance, but penetrates only a short way into the coronal region. In the soft state, the optically thick disc moves inward and receives the majority of the dissipated energy, while the `corona' becomes optically thin and extends around much of the inner disc. The mass-accretion rate in both states is ~1x10^-8Msolar yr^-1.

[]

https://arxiv.org/pdf/astro-ph/9709007.pdf

1995MNRAS.277L..55F

The accretion luminosity of a massive black hole in an elliptical galaxy

1995-01-01

['accretion', 'accretion disks', 'galaxies active', 'galaxies jets', 'galaxies nuclei', 'astrophysics']

[]

Most large elliptical galaxies should now host a massive black hole left over from an earlier quasar phase. Such galaxies also have an extensive hot gaseous halo. Here we consider why the nuclei of elliptical galaxies are not luminous sources as a result of the accretion of the hot gas by the central black hole, yet have weak radio sources. In particular, we suggest that accretion from the hot medium has low radiative efficiency and forms a hot ion torus surrounding the black hole. Synchrotron emission from the torus can account for at least part of the weak radio sources commonly seen in otherwise normal elliptical galaxies. The inner funnel of the ion torus can also begin the collimation of a narrow jet. We speculate on the difference between jets from the nuclei of spiral and elliptical galaxies, and suggest that the extensive hot atmosphere seen in ellipticals is essential for maintaining the collimation and provoking the observed radio structures of radio galaxies. We also note that low radiative efficiency, and not necessarily a large change in accretion rate, may be responsible for the demise of quasars and may contribute to the hard X-ray background. Hot ion tori may be common in galactic nuclei.

[]

https://arxiv.org/pdf/astro-ph/9509096.pdf

2000ApJ...544L..91N

Black Hole Mass, Velocity Dispersion, and the Radio Source in Active Galactic Nuclei

2000-01-01

['galaxies kinematics and dynamics', 'galaxies nuclei', 'galaxies seyfert', 'galaxies quasars', 'astrophysics']

[]

The recent discovery by Gebhardt et al. and Ferrarese &amp; Merritt of a correlation between nuclear black hole mass M<SUB>bh</SUB> and stellar velocity dispersion σ<SUB>*</SUB> in elliptical galaxies and spiral bulges has raised the question whether such a relationship exists for active galactic nuclei (AGNs). Estimates of M<SUB>bh</SUB> for many AGNs, made using reverberation mapping techniques, allow exploration of the relationship between black hole mass, the host galaxy, and the energetics of nuclear emission. However, since only a few AGNs have both M<SUB>bh</SUB> and σ<SUB>*</SUB> measurements, we use the [O III] λ5007 emission-line widths on the assumption that for most AGNs the forbidden line kinematics are dominated by virial motion in the host galaxy bulge. We find that a relation does exist between M<SUB>bh</SUB> and the [O III] line width for AGNs, which is similar to the one found by Gebhardt et al., although with more scatter, as expected if secondary influences on the gas kinematics are also present. Our conclusion is that both active and inactive galaxies follow the same relationship between black hole mass and bulge gravitational potential. We find no compelling evidence for systematic differences in the mass estimates from reverberation mapping and stellar dynamics. We also find that for radio-quiet AGNs, the radio power and black hole mass are highly correlated, linking emission on scales of kiloparsecs with the nuclear energy source.

[]

https://arxiv.org/pdf/astro-ph/0009188.pdf

2010JHEP...01..085C

Supersymmetric AdS<SUB>4</SUB> black holes and attractors

2010-01-01

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

[]

Using the general recipe given in arXiv:0804.0009, where all timelike supersymmetric solutions of mathcal{N} = 2 , D = 4 gauged supergravity coupled to abelian vector multiplets were classified, we construct the first examples of genuine supersymmetric black holes in AdS<SUB>4</SUB> with nonconstant scalar fields. This is done for various choices of the prepotential, amongst others for the STU model. These solutions permit to study the BPS attractor flow in AdS. We also determine the most general supersymmetric static near-horizon geometry and obtain the attractor equations in gauged supergravity. As a general feature we find the presence of flat directions in the black hole potential, i.e., generically the values of the moduli on the horizon are not completely specified by the charges. For one of the considered prepotentials, the resulting moduli space is determined explicitely. Still, in all cases, we find that the black hole entropy depends only on the charges, in agreement with the attractor mechanism.

[]

https://arxiv.org/pdf/0911.4926.pdf

2007PhRvL..99d1102K

Recoil Velocities from Equal-Mass Binary-Black-Hole Mergers

2007-01-01

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

[]

The final evolution of a binary-black-hole system gives rise to a recoil velocity if an asymmetry is present in the emitted gravitational radiation. Measurements of this effect for nonspinning binaries with unequal masses have pointed out that kick velocities ∼175km/s can be reached for a mass ratio ≃0.36. However, a larger recoil can be obtained for equal-mass binaries if the asymmetry is provided by the spins. Using two independent methods we show that the merger of such binaries yields velocities as large as ∼440km/s for black holes having unequal spins that are antialigned and parallel to the orbital angular momentum.

[]

https://arxiv.org/pdf/gr-qc/0701163.pdf

2005ApJ...620...59S

Spin, Accretion, and the Cosmological Growth of Supermassive Black Holes

2005-01-01

['accretion', 'accretion disks', 'black hole physics', 'cosmology theory', 'mhd', 'galaxies quasars', 'astrophysics', '-']

[]

If supermassive black holes (SMBHs) are the energy sources that power quasars and active galactic nuclei (AGNs), then QSO SDSS 1148+5251, the quasar with the highest redshift (z<SUB>QSO</SUB>=6.43), hosts an SMBH formed within ~0.9 Gyr after the big bang. This requirement places constraints on the cosmological formation of SMBHs, believed to grow from smaller initial seeds by a combination of accretion and mergers. We focus on gas accretion onto seeds produced by the collapse of Population III stars at high redshift. We incorporate the results of recent relativistic, MHD simulations of disk accretion onto Kerr black holes to track the coupled evolution of the masses and spins of the holes. We allow for an additional amplification of ~10<SUP>4</SUP> in the mass of a typical seed due to mergers, consistent with recent Monte Carlo simulations of hierarchical mergers of cold dark matter halos containing black hole seeds. We find that the growth of Population III black hole remnants to ~10<SUP>9</SUP> M<SUB>solar</SUB> by z<SUB>QSO</SUB>&gt;~6.43 favors MHD accretion disks over standard thin disks. MHD disks tend to drive the holes to a submaximal equilibrium spin rate a/M~0.95 and radiation efficiency ɛ<SUB>M</SUB>~0.2, while standard thin disks drive them to maximal spin (a/M=1) and efficiency (ɛ<SUB>M</SUB>=0.42). This small difference in efficiency results in a huge difference in mass amplification by accretion at the Eddington limit. The MHD equilibrium efficiency is consistent with the observed ratio of the QSO plus AGN luminosity density to the local SMBH mass density. Our prototype analysis is designed to stimulate the incorporation of results from relativistic stellar collapse and MHD accretion simulations in future Monte Carlo simulations of hierarchical structure formation to better determine the cosmological role of SMBHs and their mass and spin distributions.

[]

https://arxiv.org/pdf/astro-ph/0411156.pdf

2006JHEP...03..008S

Entropy function for heterotic black holes

2006-01-01

['-']

[]

We use the entropy function formalism to study the effect of the Gauss-Bonnet term on the entropy of spherically symmetric extremal black holes in heterotic string theory in four dimensions. Surprisingly the resulting entropy and the near horizon metric, gauge field strengths and the axion-dilaton field are identical to those obtained by Cardoso et al. for a supersymmetric version of the theory that contains Weyl tensor squared term instead of the Gauss-Bonnet term. We also study the effect of holomorphic anomaly on the entropy using our formalism. Again the resulting attractor equations for the axion-dilaton field and the black hole entropy agree with the corresponding equations for the supersymmetric version of the theory. These results suggest that there might be a simpler description of supergravity with curvature squared terms in which we supersymmetrize the Gauss-Bonnet term instead of the Weyl tensor squared term.

[]

https://arxiv.org/pdf/hep-th/0508042.pdf

2003PhRvD..68b4024R

Higher dimensional black holes and supersymmetry

2003-01-01

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

[]

It has recently been shown that the uniqueness theorem for stationary black holes cannot be extended to five dimensions. However, uniqueness is an important assumption of the string theory black hole entropy calculations. This paper justifies this assumption by proving a uniqueness theorem for supersymmetric black holes in five dimensions. Some remarks concerning general properties of nonsupersymmetric higher dimensional black holes are made. It is conjectured that there exist new families of stationary higher dimensional black hole solutions with fewer symmetries than any known solution.

[]

https://arxiv.org/pdf/hep-th/0211290.pdf

2019ApJ...872..151M

Weighing Black Holes Using Tidal Disruption Events

2019-01-01

['galaxies active', 'galaxies quasars', 'stars black holes', '-', '-']

[]

While once rare, observations of stars being tidally disrupted by supermassive black holes are quickly becoming commonplace. To continue to learn from these events, it is necessary to robustly and systematically compare our growing number of observations with theory. We present a tidal disruption module for the Modular Open Source Fitter for Transients (MOSFiT) and the results from fitting 14 tidal disruption events (TDEs). Our model uses FLASH simulations of TDEs to generate bolometric luminosities and passes these luminosities through viscosity and reprocessing transformation functions to create multiwavelength light curves. It then uses an MCMC fitting routine to compare these theoretical light curves with observations. We find that none of the events show evidence for viscous delays exceeding a few days, supporting the theory that our current observing strategies in the optical/UV are missing a significant number of viscously delayed flares. We find that the events have black hole masses of 10<SUP>6</SUP>-10<SUP>8</SUP> M <SUB>⊙</SUB> and that the masses we predict are as reliable as those based on bulk galaxy properties. We also find that there is a preference for stars with mass &lt;1 M <SUB>⊙</SUB>, as expected when low-mass stars greatly outnumber high-mass stars.

[]

https://arxiv.org/pdf/1801.08221.pdf

2017PhRvD..95b4010B

Validating the effective-one-body model of spinning, precessing binary black holes against numerical relativity

2017-01-01

['-']

[]

In Abbott et al. [Phys. Rev. X 6, 041014 (2016), 10.1103/PhysRevX.6.041014], the properties of the first gravitational wave detected by LIGO, GW150914, were measured by employing an effective-one-body (EOB) model of precessing binary black holes whose underlying dynamics and waveforms were calibrated to numerical-relativity (NR) simulations. Here, we perform the first extensive comparison of such an EOBNR model to 70 precessing NR waveforms that span mass ratios from 1 to 5, dimensionless spin magnitudes up to 0.5, generic spin orientations, and length of about 20 orbits. We work in the observer's inertial frame and include all ℓ=2 modes in the gravitational-wave polarizations. We introduce new prescriptions for the EOB ringdown signal concerning its spectrum and time of onset. For total masses between 10 M<SUB>⊙</SUB> and 200 M<SUB>⊙</SUB> , we find that precessing EOBNR waveforms have unfaithfulness within about 3% to NR waveforms when considering the Advanced-LIGO design noise curve. This result is obtained without recalibration of the inspiral-plunge signal of the underlying nonprecessing EOBNR model. The unfaithfulness is computed with maximization over time and phase of arrival, sky location, and polarization of the EOBNR waveform, and it is averaged over sky location and polarization of the NR signal. We also present comparisons between NR and EOBNR waveforms in a frame that tracks the orbital precession.

[]

https://arxiv.org/pdf/1607.05661.pdf

2008ApJ...674L..25W

Testing the General Relativistic "No-Hair" Theorems Using the Galactic Center Black Hole Sagittarius A*

2008-01-01

['black hole physics', 'galaxy center', 'relativity', 'astrophysics', '-']

[]

If a class of stars orbits the central black hole in our galaxy in short-period (~0.1 yr), high-eccentricity (~0.9) orbits, they will experience precessions of their orbital planes induced by both relativistic frame dragging and the quadrupolar gravity of the hole, at levels that could be as large as 10 μas per year, if the black hole is rotating faster than half of its maximum rotation rate. Astrometric observations of the orbits of at least two such stars can in principle lead to a determination of the angular momentum vector \boldsymbol{J} of the black hole and its quadrupole moment Q<SUB>2</SUB>. This could lead to a test of the general relativistic no-hair theorems, which demand that Q<SUB>2</SUB> = - J<SUP>2</SUP>/M. Future high-precision adaptive infrared optics instruments may make such a fundamental test of the black hole paradigm possible.

[]

https://arxiv.org/pdf/0711.1677.pdf

1994gr.qc.....4039J

Black Hole Entropy and Induced Gravity

1994-01-01

['-', '-']

[]

In this short essay we review the arguments showing that black hole entropy is, at least in part, ``entanglement entropy", i.e., missing information contained in correlations between quantum field fluctuations inside and outside the event horizon. Although the entanglement entropy depends upon the matter field content of the theory, it turns out that so does the Bekenstein-Hawking entropy $A/4\hbar G_{ren}$, in precisely the same way, because the effective gravitational constant $G_{ren}$ is renormalized by the very same quantum fluctuations. It appears most satisfactory if the entire gravitational action is ``induced", in the manner suggested by Sakharov, since then the black hole entropy is purebred entanglement entropy, rather than being hybrid with bare gravitational entropy (whatever that might be.)

[]

https://arxiv.org/pdf/gr-qc/9404039.pdf

2000ApJ...545..847M

A Cluster of Black Holes at the Galactic Center

2000-01-01

['black hole physics', 'galaxy center', 'galaxy kinematics and dynamics', 'astrophysics']

[]

If the stellar population of the bulge contains black holes formed in the final core collapse of ordinary stars with M&gt;~30 M<SUB>solar</SUB>, then about 25,000 stellar mass black holes should have migrated by dynamical friction into the central parsec of the Milky Way, forming a black hole cluster around the central supermassive black hole. These black holes can be captured by the central black hole when they randomly reach a highly eccentric orbit due to relaxation, either by direct capture (when their Newtonian peribothron is less than 4 Schwarzschild radii) or after losing orbital energy through gravitational waves. The overall depletion timescale is ~30 Gyr, so most of the 25,000 black holes remain in the central cluster today. The presence of this black hole cluster would have several observable consequences. First, the low-mass, old stellar population should have been expelled from the region occupied by the black hole cluster as a result of relaxation, implying a core in the profile of solar-mass red giants with a radius of ~2 pc (i.e., 1<SUP>'</SUP>). The observed central density cusp (which has a core radius of only a few arcseconds) should be composed primarily of young (&lt;~1 Gyr) stars. Second, flares from stars being captured by supermassive black holes in other galaxies should be rarer than usually expected because the older stars will have been expelled from the central regions by the black hole clusters of those galaxies. Third, the young (&lt;~2 Gyr) stars found at distances ~3-10 pc from the Galactic center should be preferentially on highly eccentric orbits. Fourth, if future high-resolution K-band images reveal sources microlensed by the Milky Way's central black hole, then the cluster black holes could give rise to secondary (``planet-like'') perturbations on the main event.

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https://arxiv.org/pdf/astro-ph/0003269.pdf

2010JHEP...04..019B

Black hole superradiance from Kerr/CFT

2010-01-01

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

[]

The superradiant scattering of a scalar field with frequency and angular momentum ( ω, m) by a near-extreme Kerr black hole with mass and spin ( M, J) was derived in the seventies by Starobinsky, Churilov, Press and Teukolsky. In this paper we show that for frequencies scaled to the superradiant bound the full functional dependence on ( ω, m, M, J) of the scattering amplitudes is precisely reproduced by a dual two-dimensional conformal field theory in which the black hole corresponds to a specific thermal state and the scalar field to a specific operator. This striking agreement corroborates a conjectured Kerr/CFT correspondence.

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https://arxiv.org/pdf/0907.3477.pdf

2004PhRvD..70d9903C

Publisher's Note: Black-hole bomb and superradiant instabilities [Phys. Rev. D 70, 044039 (2004)]

2004-01-01

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

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This paper was published online on 26 August 2004 with a typographical error in Ref. [26]. The author of the second paper of Ref. [26] should be P. Mészáros. The name has been corrected as of 27 August 2004. The reference is correct in the printed version of the journal.

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https://arxiv.org/pdf/hep-th/0404096.pdf

2003GReGr..35..129F

Letter: Charged Black Hole Solutions in Einstein-Born-Infeld Gravity with a Cosmological Constant

2003-01-01

['-']

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We construct black hole solutions to Einstein-Born-Infeld gravity with a cosmological constant. Since an elliptic function appears in the solutions for the metric, we construct horizons numerically. The causal structure of these solutions differs drastically from their counterparts in Einstein-Maxwell gravity with a cosmological constant. The charged de-Sitter black holes can have up to three horizons and the charged anti-de Sitter black hole can have one or two depending on the parameters chosen.

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https://arxiv.org/pdf/hep-th/0306120.pdf

2002PhRvD..66l4013S

Quasinormal modes of near extremal black branes

2002-01-01

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

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We find quasinormal modes of near extremal black branes by solving a singular boundary value problem for the Heun equation. The corresponding eigenvalues determine the dispersion law for the collective excitations in the dual strongly coupled N=4 supersymmetric Yang-Mills theory at finite temperature.

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https://arxiv.org/pdf/hep-th/0207133.pdf