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2021EPJP..136..436W | Testing the nature of Gauss-Bonnet gravity by four-dimensional rotating black hole shadow | 2021-01-01 | 35 | 0.46 | 189 | ['-', '-'] | [] | The recent discovery of the novel four-dimensional static and spherically symmetric Gauss-Bonnet black hole provides a promising bed to test Gauss-Bonnet gravity by using astronomical observations (Glavan et al. in PRL 124:081301, 2020). In this paper, we first obtain the rotating Gauss-Bonnet black hole solution by using the Newman-Janis algorithm and then study the shadow cast by the nonrotating and rotating candidate Gauss-Bonnet black holes. The result indicates that positive metric parameter α shrinks the shadow, while negative one enlarges it. Meanwhile, both the distortion and ratio of two diameters of the shadow are found to increase with the metric parameter for certain spin. Comparing with the Kerr black hole, the shadow gets more distorted for α and less distorted for negative one. Furthermore, we calculate the angular diameter of the shadow by making use of the observation of M87*. The result indicates that negative metric parameter α in (−4.5, 0) is more favored. Since the negative energy appears for negative α , our results extends the study of Gauss-Bonnet gravity. We believe further study on the four-dimensional rotating black hole may shed new light on Gauss-Bonnet gravity. | [] | 2 | https://arxiv.org/pdf/2003.07769.pdf |
2018PhRvL.120s1102W | Constraints on the Primordial Black Hole Abundance from the First Advanced LIGO Observation Run Using the Stochastic Gravitational-Wave Background | 2018-01-01 | 24 | 0.47 | 189 | ['-', '-', '-'] | [] | Advanced LIGO's discovery of gravitational-wave events is stimulating extensive studies on the origin of binary black holes. Assuming that the gravitational-wave events can be explained by binary primordial black hole mergers, we utilize the upper limits on the stochastic gravitational-wave background given by Advanced LIGO as a new observational window to independently constrain the abundance of primordial black holes in dark matter. We show that Advanced LIGO's first observation run gives the best constraint on the primordial black hole abundance in the mass range 1 M<SUB>⊙</SUB>≲M<SUB>PBH</SUB>≲100 M<SUB>⊙</SUB>, pushing the previous microlensing and dwarf galaxy dynamics constraints tighter by 1 order of magnitude. Moreover, we discuss the possibility to detect the stochastic gravitational-wave background from primordial black holes, in particular from subsolar mass primordial black holes, by Advanced LIGO in the near future. | [] | 4 | https://arxiv.org/pdf/1610.08725.pdf |
2016arXiv160705256A | The Complexity of Quantum States and Transformations: From Quantum Money to Black Holes | 2016-01-01 | 63 | 0.46 | 189 | ['-', 'methods numerical', '-'] | [] | These are lecture notes from a weeklong course in quantum complexity theory taught at the Bellairs Research Institute in Barbados, February 21-25, 2016. The focus is quantum circuit complexity---i.e., the minimum number of gates needed to prepare a given quantum state or apply a given unitary transformation---as a unifying theme tying together several topics of recent interest in the field. Those topics include the power of quantum proofs and advice states; how to construct quantum money schemes secure against counterfeiting; and the role of complexity in the black-hole information paradox and the AdS/CFT correspondence (through connections made by Harlow-Hayden, Susskind, and others). The course was taught to a mixed audience of theoretical computer scientists and quantum gravity / string theorists, and starts out with a crash course on quantum information and computation in general. | [] | 1 | https://arxiv.org/pdf/1607.05256.pdf |
2018CQGra..35h4002V | Scattering of two spinning black holes in post-Minkowskian gravity, to all orders in spin, and effective-one-body mappings | 2018-01-01 | 33 | 0.46 | 189 | ['-'] | [] | We demonstrate equivalences, under simple mappings, between the dynamics of three distinct systems—(i) an arbitrary-mass-ratio two-spinning-black-hole system, (ii) a spinning test black hole in a background Kerr spacetime, and (iii) geodesic motion in Kerr—when each is considered in the first post-Minkowskian (1PM) approximation to general relativity, i.e. to linear order G but to all orders in 1/c, and to all orders in the black holes’ spins, with all orders in the multipole expansions of their linearized gravitational fields. This is accomplished via computations of the net results of weak gravitational scattering encounters between two spinning black holes, namely the net O(G) changes in the holes’ momenta and spins as functions of the incoming state. The results are given in remarkably simple closed forms, found by solving effective Mathisson-Papapetrou-Dixon-type equations of motion for a spinning black hole in conjunction with the linearized Einstein equation, with appropriate matching to the Kerr solution. The scattering results fully encode the gauge-invariant content of a canonical Hamiltonian governing binary-black-hole dynamics at 1PM order, for generic (unbound and bound) orbits and spin orientations. We deduce one such Hamiltonian, which reproduces and resums the 1PM parts of all such previous post-Newtonian results, and which directly manifests the equivalences with the test-body limits via simple effective-one-body mappings. | [] | 1 | https://arxiv.org/pdf/1709.06016.pdf |
2019PhRvD.100j4024G | Black-hole scattering with general spin directions from minimal-coupling amplitudes | 2019-01-01 | 18 | 0.46 | 189 | ['-', '-'] | [] | We study the link between classical scattering of spinning black holes and quantum amplitudes for massive spin-s particles. Generic spin orientations of the black holes are considered, allowing their spins to be deflected on par with their momenta. We rederive the spin-exponentiated structure of the relevant tree-level amplitude from minimal coupling to Einstein's gravity, which in the s →∞ limit generates the black holes' complete series of spin-induced multipoles. The resulting scattering function is seen to encode in a simple way the known net changes in the black-hole momenta and spins at first post-Minkowskian order. We connect our findings to a rigorous framework developed elsewhere for computing such observables from amplitudes. | [] | 3 | https://arxiv.org/pdf/1906.10071.pdf |
2002PhRvD..66b4044C | Anti-de Sitter black holes, thermal phase transition, and holography in higher curvature gravity | 2002-01-01 | 5 | 0.46 | 188 | ['-', '-', '-', '-', '-', '-', '-', 'particles', '-'] | [] | We study anti-de Sitter black holes in the Einstein-Gauss-Bonnet and the generic R<SUP>2</SUP> gravity theories, evaluate different thermodynamic quantities, and also examine the possibilities of Hawking-Page-type thermal phase transitions in these theories. In the Einstein theory, with a possible cosmological term, one observes a Hawking-Page phase transition only if the event horizon is a hypersurface of positive constant curvature (k=1). But, with the Gauss-Bonnet and/or the (Riemann)<SUP>2</SUP> interaction terms, there may occur a similar phase transition for a horizon of negative constant curvature (k=-1). We examine the finite coupling effects, and find that N>5 could trigger a Hawking-Page phase transition in the latter theory. For the Gauss-Bonnet black holes, one relates the entropy of the black hole to a variation of the geometric property of the horizon based on the first law and Noether charge. With a (Riemann)<SUP>2</SUP> term, however, we can do this only approximately, and the two results agree when r<SUB>H</SUB>>>L, the size of the horizon is much bigger than the AdS curvature scale. We establish some relations between bulk data associated with the AdS black hole and boundary data defined on the horizon of the AdS geometry. Following a heuristic approach, we estimate the difference between Hubble entropy (S<SUB>H</SUB>) and Bekenstein-Hawking entropy (S<SUB>BH</SUB>) with a (Riemann)<SUP>2</SUP> term, which, for k=0 and k=-1, implies S<SUB>BH</SUB><=S</ scr><SUB>H</SUB>. | [] | 2 | https://arxiv.org/pdf/hep-th/0202140.pdf |
2004MNRAS.347..885G | Black hole accretion discs: reality confronts theory | 2004-01-01 | 10 | 0.52 | 188 | ['accretion', 'accretion disks', 'astronomy x rays', 'astrophysics'] | [] | Disc spectra from highly luminous black hole binaries are observed to be rather simple, despite theoretical predictions to the contrary. We collate the disc-dominated spectra from multiple observations of 10 separate sources and show that they are consistent with a simple multicolour blackbody with a disc luminosity of L<SUB>disc</SUB>~T<SUP>4</SUP> over two orders of magnitude. This is probably compatible with the predictions of standard Shakura-Sunyaev α-disc theory. However, these models also predict that the radiation-pressure-dominated disc is unstable, in strong conflict to the observed lack of variability of the light curves. We show that this discrepancy is unlikely to be resolved by modifications such as additional energy loss in a jet, a wind or a corona. This motivates consideration of alternative disc models, in particular the β-discs, where the viscous heating is proportional to gas pressure, which are stable. While proper calculations have yet to be performed, it seems likely that such models predict significant departures from a simple L<SUB>disc</SUB>~T<SUP>4</SUP> relation, again in conflict with the observations. More generally, this shows that accretion disc spectra can give reliable constraints on the disc structure, and should be used to test the next generation of accretion disc models, in which the disc viscosity is calculated self-consistently from the magnetically generated turbulent dynamo. | [] | 2 | https://arxiv.org/pdf/astro-ph/0307333.pdf |
2022PhR...955....1M | Merging stellar-mass binary black holes | 2022-01-01 | 75 | 0.57 | 188 | ['gravitational waves', 'black hole physics', '-', '-', '-'] | [] | The LIGO and Virgo detectors have directly observed gravitational waves from mergers of pairs of stellar-mass black holes, along with a smaller number of mergers involving neutron stars. These observations raise the hope that compact object mergers could be used as a probe of stellar and binary evolution, and perhaps of stellar dynamics. This colloquium-style article summarises the existing observations, describes theoretical predictions for formation channels of merging stellar-mass black-hole binaries along with their rates and observable properties, and presents some prospects for gravitational-wave astronomy. | [] | 2 | https://arxiv.org/pdf/1806.05820.pdf |
2018PhRvD..98h1501F | Remnant baryon mass in neutron star-black hole mergers: Predictions for binary neutron star mimickers and rapidly spinning black holes | 2018-01-01 | 32 | 0.51 | 188 | ['-', '-'] | [] | Gravitational-wave (GW) and electromagnetic (EM) signals from the merger of a neutron star (NS) and a black hole (BH) are a highly anticipated discovery. We present a simple formula, validated with 75 simulations, that distinguishes between potential merger outcomes and predicts the baryon mass left outside of the BH after merger. Our formula describes critical unexplored regimes: comparable masses with nonspinning BHs, and higher BH spins, and is essential in assessing whether events such as GW170817 could be NS-BH systems instead of NS-NS mergers. | [] | 3 | https://arxiv.org/pdf/1807.00011.pdf |
2002ApJ...572L..39S | Collapse of a Rotating Supermassive Star to a Supermassive Black Hole: Fully Relativistic Simulations | 2002-01-01 | 7 | 0.48 | 188 | ['black hole physics', 'hydrodynamics', 'relativity', '-', 'astrophysics', '-'] | [] | We follow the collapse in axisymmetry of a uniformly rotating, supermassive star (SMS) to a supermassive black hole in full general relativity. The initial SMS of arbitrary mass M is marginally unstable to radial collapse and rotates at the mass-shedding limit. The collapse proceeds homologously early on and results in the appearance of an apparent horizon at the center. Although our integration terminates before final equilibrium is achieved, we determine that the final black hole will contain about 90% of the total mass of the system and will have a spin parameter J/M<SUP>2</SUP>~0.75. The remaining gas forms a rotating disk about the nascent hole. | [] | 2 | https://arxiv.org/pdf/astro-ph/0205091.pdf |
2014ApJ...790..145D | Black Hole Mass Estimates and Emission-line Properties of a Sample of Redshift z > 6.5 Quasars | 2014-01-01 | 28 | 0.49 | 188 | ['galaxies photometry', 'galaxies quasars', '-'] | [] | We present the analysis of optical and near-infrared spectra of the only four z > 6.5 quasars known to date, discovered in the UKIDSS-LAS and VISTA-VIKING surveys. Our data set consists of new Very Large Telescope/X-Shooter and Magellan/FIRE observations. These are the best optical/NIR spectroscopic data that are likely to be obtained for the z > 6.5 sample using current 6-10 m facilities. We estimate the black hole (BH) mass, the Eddington ratio, and the Si IV/C IV, C III]/C IV, and Fe II/Mg II emission-line flux ratios. We perform spectral modeling using a procedure that allows us to derive a probability distribution for the continuum components and to obtain the quasar properties weighted upon the underlying distribution of continuum models. The z > 6.5 quasars show the same emission properties as their counterparts at lower redshifts. The z > 6.5 quasars host BHs with masses of ~10<SUP>9</SUP> M <SUB>⊙</SUB> that are accreting close to the Eddington luminosity (langlog(L <SUB>Bol</SUB>/L <SUB>Edd</SUB>)rang = -0.4 ± 0.2), in agreement with what has been observed for a sample of 4.0 < z < 6.5 quasars. By comparing the Si IV/C IV and C III]/C IV flux ratios with the results obtained from luminosity-matched samples at z ~ 6 and 2 <= z <= 4.5, we find no evidence of evolution of the line ratios with cosmic time. We compare the measured Fe II/Mg II flux ratios with those obtained for a sample of 4.0 < z < 6.4 sources. The two samples are analyzed using a consistent procedure. There is no evidence that the Fe II/Mg II flux ratio evolves between z = 7 and z = 4. Under the assumption that the Fe II/Mg II traces the Fe/Mg abundance ratio, this implies the presence of major episodes of chemical enrichment in the quasar hosts in the first ~0.8 Gyr after the Big Bang. <P />Based on observations collected at the European Southern Observatory, Chile, programs 286.A-5025, 087.A-0890, and 088.A-0897. This paper also includes data gathered with the 6.5 m Magellan Telescope located at Las Campanas Observatory, Chile. | [] | 13 | https://arxiv.org/pdf/1311.3260.pdf |
2016JHEP...09..161C | Action growth for AdS black holes | 2016-01-01 | 26 | 0.46 | 188 | ['black hole physics', '-', '-', '-'] | [] | Recently a Complexity-Action (CA) duality conjecture has been proposed, which relates the quantum complexity of a holographic boundary state to the action of a Wheeler-DeWitt (WDW) patch in the anti-de Sitter (AdS) bulk. In this paper we further investigate the duality conjecture for stationary AdS black holes and derive some exact results for the growth rate of action within the Wheeler-DeWitt (WDW) patch at late time approximation, which is supposed to be dual to the growth rate of quantum complexity of holographic state. Based on the results from the general D-dimensional Reissner-Nordström (RN)-AdS black hole, rotating/charged Bañados-Teitelboim-Zanelli (BTZ) black hole, Kerr-AdS black hole and charged Gauss-Bonnet-AdS black hole, we present a universal formula for the action growth expressed in terms of some thermodynamical quantities associated with the outer and inner horizons of the AdS black holes. And we leave the conjecture unchanged that the stationary AdS black hole in Einstein gravity is the fastest computer in nature. | [] | 5 | https://arxiv.org/pdf/1606.08307.pdf |
1995PhRvD..51.4315T | Action and entropy of extreme and nonextreme black holes | 1995-01-01 | 3 | 0.46 | 187 | ['-', '-', '-', '-', '-', '-', '-', '-', 'black hole physics', '-', '-'] | [] | The Hamiltonian actions for extreme and nonextreme black holes are compared and contrasted and a simple derivation of the lack of entropy of extreme black holes is given. In the nonextreme case the wave function of the black hole depends on horizon degrees of freedom which give rise to the entropy. Those additional degrees of freedom are absent in the extreme case. | [] | 1 | https://arxiv.org/pdf/hep-th/9410103.pdf |
1999NuPhB.545..434C | Supersymmetry of anti-de Sitter black holes | 1999-01-01 | 11 | 0.46 | 187 | ['-', '-'] | [] | We examine supersymmetry of four-dimensional asymptotically anti-de Sitter (AdS) dyonic black holes in the context of gauged N = 2 supergravity. Our calculations concentrate on black holes with unusual topology and their rotating generalizations, but we also reconsider the spherical rotating dyonic Ker-Newman-AdS black hole, whose supersymmetry properties have previously been investigated by Kostelecký and Perry within another approach. We find that in the case of spherical, toroidal or cylindrical event horizon topology, the black holes must rotate in order to preserve some supersymmetry; the non-rotating supersymmetric configurations representing naked singularities. However, we show that this is no more true for black holes whose event horizons are Riemann surfaces of genus g > 1, where we find a non-rotating extremal solitonic black hole carrying magtetic charge and permitting one Killing spinor. For the non-rotating supersymmetric configurations of various topologies, all Killing spinors are explicitly constructed. | [] | 2 | https://arxiv.org/pdf/hep-th/9808097.pdf |
2009PhRvD..79j3520J | Generalized constraints on the curvature perturbation from primordial black holes | 2009-01-01 | 18 | 0.46 | 187 | ['-', 'particles', '-', '-'] | [] | Primordial black holes (PBHs) can form in the early Universe via the collapse of large density perturbations. There are tight constraints on the abundance of PBHs formed due to their gravitational effects and the consequences of their evaporation. These abundance constraints can be used to constrain the primordial power spectrum, and hence models of inflation, on scales far smaller than those probed by cosmological observations. We compile, and where relevant update, the constraints on the abundance of PBHs before calculating the constraints on the curvature perturbation, taking into account the growth of density perturbations prior to horizon entry. We consider two simple parametrizations of the curvature perturbation spectrum on the scale of interest: constant and power-law. The constraints from PBHs on the amplitude of the power spectrum are typically in the range 10<SUP>-2</SUP>-10<SUP>-1</SUP> with some scale dependence. | [] | 3 | https://arxiv.org/pdf/0903.3184.pdf |
2011PhRvL.107w1102L | Hangup Kicks: Still Larger Recoils by Partial Spin-Orbit Alignment of Black-Hole Binaries | 2011-01-01 | 31 | 0.48 | 187 | ['-', '-', '-', '-', 'methods numerical', '-', 'perturbation theory', '-', 'waves', '-', '-', '-', '-', '-'] | [] | We revisit the scenario of the gravitational radiation recoil acquired by the final remnant of a black-hole-binary merger by studying a set of configurations that have components of the spin both aligned with the orbital angular momentum and in the orbital plane. We perform a series of 42 new full numerical simulations for equal-mass and equal-spin-magnitude binaries. We extend previous recoil fitting formulas to include nonlinear terms in the spins and successfully include both the new and known results. The new predicted maximum velocity approaches 5000km/s for spins partially aligned with the orbital angular momentum, which leads to an important increase of the probabilities of large recoils in generic astrophysical mergers. We find non-negligible probabilities for recoils of several thousand km/s from accretion-aligned binaries. | [] | 2 | https://arxiv.org/pdf/1108.2009.pdf |
2016NatAs...1E...2L | The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole | 2016-01-01 | 71 | 0.54 | 187 | ['-', '-', '-'] | [] | When a star passes within the tidal radius of a supermassive black hole, it will be torn apart<SUP>1</SUP>. For a star with the mass of the Sun (M <SUB>⊙</SUB>) and a non-spinning black hole with a mass <10<SUP>8</SUP> M <SUB>⊙</SUB>, the tidal radius lies outside the black hole event horizon<SUP>2</SUP> and the disruption results in a luminous flare<SUP>3-6</SUP>. Here we report observations over a period of ten months of a transient, hitherto interpreted<SUP>7</SUP> as a superluminous supernova<SUP>8</SUP>. Our data show that the transient rebrightened substantially in the ultraviolet and that the spectrum went through three different spectroscopic phases without ever becoming nebular. Our observations are more consistent with a tidal disruption event than a superluminous supernova because of the temperature evolution<SUP>6</SUP>, the presence of highly ionized CNO gas in the line of sight<SUP>9</SUP> and our improved localization of the transient in the nucleus of a passive galaxy, where the presence of massive stars is highly unlikely<SUP>10,11</SUP>. While the supermassive black hole has a mass >10<SUP>8</SUP> M <SUB>⊙</SUB> <SUP>12,13</SUP>, a star with the same mass as the Sun could be disrupted outside the event horizon if the black hole were spinning rapidly<SUP>14</SUP>. The rapid spin and high black hole mass can explain the high luminosity of this event. | [] | 50 | https://arxiv.org/pdf/1609.02927.pdf |
2018A&A...616A..28Q | The spin of the second-born black hole in coalescing binary black holes | 2018-01-01 | 33 | 0.54 | 187 | ['stars binaries close', 'stars black holes', '-', 'sun rotation', 'gamma rays', 'stars wolf rayet', '-', '-'] | [] | Context. Various binary black hole formation channels have been proposed since the first gravitational event GW150914 was discovered by the Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO). The immediate progenitor of the binary black hole is a close binary system composed of a black hole and a helium star, which can be the outcome of the classical isolated binary evolution through the common envelope, or alternatively of the massive close evolution through chemically homogeneous channel. <BR /> Aims: We study the spin angular momentum evolution of the helium star in order to constrain the spin of the second-born black hole. This work focuses on the common envelope formation channel, however, some of our conclusions are also relevant for the chemically homogeneous evolution channel. <BR /> Methods: We perform detailed stellar structure and binary evolution calculations that take into account, mass-loss, internal differential rotation, and tidal interactions between the helium star and the black hole companion, where we also calculate the strength of the tidal interactions from first principles based on the structure of the helium stars. We systematically explore the parameter space of initial binary properties, including initial black hole and helium star masses, initial rotation of the helium star as well as metallicity. <BR /> Results: We argue that the natal spin of the first-born black hole through the common envelope scenario is negligible (≲0.1), and therefore the second-born black hole's spin dominates the measured effective spin, χ<SUB>eff</SUB>, from gravitational wave events of double black hole mergers. We find that tides can be only important when orbital periods are shorter than 2 days. Upon core collapse, the helium star produces a black hole (the second-born black hole in the system) with a spin that can span the entire range from zero to maximally spinning. We show that the bimodal distribution of the spin of the second-born black hole obtained in recent papers is mainly due to oversimplifying assumptions. We find an anti-correlation between the merging timescale of the two black holes, T<SUB>merger</SUB>, and the effective spin χ<SUB>eff</SUB>. Finally, we provide new prescriptions for the tidal coefficient E<SUB>2</SUB> for both H-rich and the He-rich stars. <BR /> Conclusions: To understand the spin of the second-born black hole, careful treatment of both tides and stellar winds is needed. We predict that, with future improvements to AdLIGO's sensitivity, the sample of merging binary black hole systems will show an overdensity of sources with positive but small χ<SUB>eff</SUB> originating from lower-mass black hole mergers born at low redshift. | [] | 6 | https://arxiv.org/pdf/1802.05738.pdf |
2013ApJ...773...90G | Stellar Velocity Dispersion Measurements in High-luminosity Quasar Hosts and Implications for the AGN Black Hole Mass Scale | 2013-01-01 | 26 | 0.52 | 186 | ['galaxies active', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'galaxies quasars', '-'] | [] | We present new stellar velocity dispersion measurements for four luminous quasars with the Near-Infrared Integral Field Spectrometer instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8 m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole (BH) masses in luminous quasars are necessary to investigate the coevolution of BHs and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass BHs are not offset with respect to the M <SUB>BH</SUB>-σ<SUB>*</SUB> relation exhibited by lower-luminosity active galactic nuclei (AGNs) with lower-mass BHs, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor langfrang that places the reverberation data on the quiescent M <SUB>BH</SUB>-σ<SUB>*</SUB> relation. With our updated measurements and new additions to the AGN sample, we obtain langfrang = 4.31 ± 1.05, which is slightly lower than, but consistent with, most previous determinations. | [] | 10 | https://arxiv.org/pdf/1305.2447.pdf |
2012Natur.491..729V | An over-massive black hole in the compact lenticular galaxy NGC 1277 | 2012-01-01 | 28 | 0.51 | 186 | ['-'] | [] | Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10<SUP>11</SUP> solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10<SUP>10</SUP> solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations. | [] | 6 | https://arxiv.org/pdf/1211.6429.pdf |
2004ApJ...607L...5F | How Black Holes Get Their Kicks: Gravitational Radiation Recoil Revisited | 2004-01-01 | 8 | 0.47 | 186 | ['black hole physics', 'galaxies nuclei', 'gravitation', 'gravitational waves', 'astrophysics', '-'] | [] | Gravitational waves from the coalescence of binary black holes carry away linear momentum, causing center of mass recoil. This ``radiation rocket'' effect has important implications for systems with escape speeds of order the recoil velocity. We revisit this problem using black hole perturbation theory, treating the binary as a test mass spiraling into a spinning hole. For extreme mass ratios (q≡m<SUB>1</SUB>/m<SUB>2</SUB><<1), we compute the recoil for the slow in-spiral epoch of binary coalescence very accurately; these results can be extrapolated to q~0.4 with modest accuracy. Although the recoil from the final plunge contributes significantly to the final recoil, we are only able to make crude estimates of its magnitude. We find that the recoil can easily reach ~100-200 km s<SUP>-1</SUP> but most likely does not exceed ~500 km s<SUP>-1</SUP>. Although much lower than previous estimates, this recoil is large enough to have important astrophysical consequences. These include the ejection of black holes from globular clusters, dwarf galaxies, and high-redshift dark matter halos. | [] | 3 | https://arxiv.org/pdf/astro-ph/0402056.pdf |
2002ApJ...569..362S | Two Different Long-Term Behaviors in Black Hole Candidates: Evidence for Two Accretion Flows? | 2002-01-01 | 12 | 0.48 | 186 | ['accretion', 'accretion disks', 'black hole physics', '-', 'galaxies quasars', '-', '-', '-', 'astronomy x rays', 'astrophysics'] | [] | We discuss the results of long-term hard X-ray monitoring of Galactic black hole candidates 1E 1740.7-2942, GRS 1758-258, Cyg X-1, GX 339-4, and Cyg X-3 with the Rossi X-Ray Timing Explorer. The objects divide into two classes. In the first class, exemplified by Cyg X-1, luminosity and spectral hardness evolve simultaneously. In the second class, the relation is more complicated: the softest spectra occur while the count rate is dropping. Most models of accretion, tailored to Cyg X-1, do not predict the second sort of behavior. One interpretation is a simple model with two simultaneous, independent accretion flows: a thin disk and a hot halo. A drop in the accretion rate affecting both flows would propagate through the halo immediately but might take up to several weeks to propagate through the disk. While the inner halo is thus temporarily depleted compared to the disk, a temporary soft state is expected. This picture is supported by the observation that those sources that show delays (1E 1740.7-2942, GRS 1758-258, and GX 339-4) are expected to have low-mass companions, and those that do not (Cyg X-1, Cyg X-3) are known or thought to have high-mass companions. Low-mass companions imply accretion by Roche lobe overflow, with a high specific angular momentum in the accreting material, and therefore a large disk with a long viscous timescale. Wind accretion from massive companions is expected to result in a much smaller disk and thus little viscous delay. | [] | 3 | https://arxiv.org/pdf/astro-ph/0103304.pdf |
1999A&A...342...49F | The jet/disk symbiosis. III. What the radio cores in GRS 1915+105, NGC 4258, M 81 and SGR A* tell us about accreting black holes | 1999-01-01 | 7 | 0.49 | 186 | ['accretion', 'accretion disks', '-', 'galaxy center', 'galaxies', 'galaxies', 'galaxies jets', 'astrophysics'] | [] | We have derived simplified equations for a freely expanding, pressure driven jet model as a function of jet power and applied it successfully to the radio cores in the black hole candidates GRS 1915+105, NGC 4258, and M 81 which are observationally well defined systems, and to Sgr A*. By using equipartition assumptions, the model has virtually no free parameters and can explain all sources by just scaling the jet power. In GRS 1915+105 it also naturally explains the jet velocity and the radio time delay. The jet powers we derive for the radio cores of the first three sources are comparable to their accretion disk luminosities, providing further evidence for the existence of symbiotic jet/disk systems and a common engine mechanism also in low-luminosity AGN and stellar mass black holes. With the exception of Sgr A* an advection dominated accretion flow (ADAF) does not seem to be necessary to explain any of the radio cores which span a large range in luminosity and size, as well as in black hole masses and accretion rate-from Eddington to extreme sub-Eddington. We suggest, however, that the jet model can be used to derive minimum accretion rates and thus find that Sgr A* seems to be truly radiatively deficient-even in a starved black hole model-and that a combination of jet and ADAF model may be one possible solution. | [] | 2 | https://arxiv.org/pdf/astro-ph/9810226.pdf |
2011PhRvD..84b4032K | Observable signatures of extreme mass-ratio inspiral black hole binaries embedded in thin accretion disks | 2011-01-01 | 35 | 0.51 | 186 | ['-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-'] | [] | We examine the electromagnetic and gravitational wave (GW) signatures of stellar-mass compact objects (COs) spiraling into a supermassive black hole (extreme mass-ratio inspirals), embedded in a thin, radiation-pressure dominated, accretion disk. At large separations, the tidal effect of the secondary CO clears a gap. We derive the conditions necessary for gap opening in a radiation-pressure dominated disk and show that the gap refills during the late GW-driven phase of the inspiral, leading to a sudden electromagnetic brightening of the source. The accretion disk leaves an imprint on the GW through its angular momentum exchange with the binary, the mass increase of the binary members due to accretion, and its gravity. We compute the disk-modified GWs both in an analytical Newtonian approximation and in a numerical effective-one-body approach. We find that disk-induced migration provides the dominant perturbation to the inspiral, with weaker effects from the mass accretion onto the CO and hydrodynamic drag. Depending on whether a gap is present, the perturbation of the GW phase is between 10 and 1000 rad per year, detectable with the future Laser Interferometer Space Antenna at high significance. The perturbation is significant for disk models with an effective viscosity proportional to gas pressure but much less so if proportional to the total pressure. The Fourier transform of the disk-modified GW in the stationary phase approximation is sensitive to disk parameters with a frequency trend different from post-Newtonian vacuum corrections. Our results suggest that observations of extreme mass-ratio inspirals may place new sensitive constraints on the physics of accretion disks. | [] | 3 | https://arxiv.org/pdf/1104.2322.pdf |
2010CQGra..27c5002H | A new approach to static numerical relativity and its application to Kaluza-Klein black holes | 2010-01-01 | 25 | 0.46 | 186 | ['-', '-'] | [] | We propose a framework for solving the Einstein equation for static and Euclidean metrics. First, we address the issue of gauge-fixing by borrowing from the Ricci-flow literature the so-called DeTurck trick, which renders the Einstein equation strictly elliptic and generalizes the usual harmonic-coordinate gauge. We then study two algorithms, Ricci-flow and Newton's method, for solving the resulting Einstein-DeTurck equation. We illustrate the use of these methods by studying localized black holes and non-uniform black strings in five-dimensional Kaluza-Klein theory, improving on previous calculations of their thermodynamic and geometric properties. We study spectra of various operators for these solutions, in particular finding the negative modes of the Lichnerowicz operator. We classify the localized solutions into two branches that meet at a minimum temperature. We find good evidence for a merger between the localized and non-uniform solutions. We also find a narrow window of localized solutions that possess negative modes yet have positive specific heat. | [] | 3 | https://arxiv.org/pdf/0905.1822.pdf |
2017PhLB..768..373C | Shadows of Einstein-dilaton-Gauss-Bonnet black holes | 2017-01-01 | 23 | 0.46 | 186 | ['-'] | [] | We study the shadows of the fully non-linear, asymptotically flat Einstein-dilaton-Gauss-Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr BHs, i.e. with the same total mass and angular momentum under similar observation conditions. In order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. Therefore, generically, EdGB BHs cannot be excluded by (near future) shadow observations alone. On the theoretical side, we find no clear signature of some exotic features of EdGB BHs on the corresponding shadows, such as the regions of negative (Komar, say) energy density outside the horizon. We speculate that this is due to the fact that the Komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the ADM mass, and consequently the corresponding shadows are smaller than those of comparable Kerr BHs. The analysis herein provides a clear example that it is the light ring impact parameter, rather than its ;size;, that determines a BH shadow. | [] | 5 | https://arxiv.org/pdf/1701.00079.pdf |
2014PhRvD..90b4073P | Shadow of five-dimensional rotating Myers-Perry black hole | 2014-01-01 | 30 | 0.46 | 186 | ['-', '-', '-', '-', '-', 'theory', '-', '-', '-'] | [] | A black hole casts a shadow as an optical appearance because of its strong gravitational field. We study the shadow cast by the five-dimensional Myers-Perry black hole with equal rotation parameters. We demonstrate that the null geodesic equation can be integrated, which provides us an opportunity to investigate the shadow cast by a black hole. The shadow of a black hole is found to be a dark zone covered by a deformed circle. Interestingly, the shapes of the black hole shadow are more distorted and the size decreases for larger black hole spins. Interestingly, it turns out that, for fixed values of the rotation parameter, the shadow is slightly smaller and less deformed than for its four-dimensional Kerr black hole counterpart. Further, the shadow of the five-dimensional Kerr black hole is concentric deformed circles. The effect of the rotation parameter on the shape and size of a naked singularity shadow is also analyzed. | [] | 4 | https://arxiv.org/pdf/1407.0834.pdf |
2009MNRAS.396..343R | Pathways to massive black holes and compact star clusters in pre-galactic dark matter haloes with virial temperatures >~10000K | 2009-01-01 | 23 | 0.5 | 185 | ['methods numerical', 'cosmology theory', 'astrophysics'] | [] | Large dynamic range numerical simulations of atomic cooling driven collapse of gas in pre-galactic dark matter haloes with T<SUB>vir</SUB> ~ 10000 K show that the gas loses 90 per cent and more of its angular momentum before rotational support sets in. In a fraction of these haloes where the metallicity is low and ultraviolet (UV) radiation suppresses H<SUB>2</SUB> cooling, conditions are thus very favourable for the rapid build-up of massive black holes. Depending on the progression of metal enrichment, the continued suppression of H<SUB>2</SUB> cooling by external and internal UV radiation and the ability to trap the entropy produced by the release of gravitational energy, the gas at the centre of the halo is expected to form a supermassive star, a stellar-mass black hole accreting at super-Eddington accretion rates or a compact star-cluster undergoing collisional run-away of massive stars at its centre. In all three cases, a massive black hole of initially modest mass finds itself at the centre of a rapid inflow of gas with inflow rates of >~1M<SUB>solar</SUB>yr<SUP>-1</SUP>. The massive black hole will thus grow quickly to a mass of 10<SUP>5</SUP>- 10<SUP>6</SUP>M<SUB>solar</SUB> until further inflow is halted either by consumption of gas by star formation or by the increasing energy and momentum feedback from the growing massive black hole. Conditions for the formation of massive seed black holes in this way are most favourable in haloes with T<SUB>vir</SUB> ~ 15000K and V<SUB>vir</SUB> ~ 20 km s<SUP>-1</SUP> with less massive haloes not allowing collapse of gas by atomic cooling and more massive haloes being more prone to fragmentation. This should imprint a characteristic mass on the mass spectrum of an early population of massive black hole seeds in pre-galactic haloes which will later grow into the observed population of supermassive black holes in galactic bulges. | [] | 2 | https://arxiv.org/pdf/0810.2802.pdf |
2001PhRvL..87m1301H | Fate of the Black String Instability | 2001-01-01 | 3 | 0.46 | 185 | ['-', '-'] | [] | Gregory and Laflamme showed that certain nonextremal black strings (and p-branes) are unstable to linearized perturbations. It is widely believed that this instability will cause the black string horizon to classically pinch off and then quantum mechanically separate, resulting in higher dimensional black holes. We argue that this cannot happen. Under very mild assumptions, classical event horizons cannot pinch off. Instead, they settle down to new static black string solutions which are not translationally invariant along the string. | [] | 2 | https://arxiv.org/pdf/hep-th/0105111.pdf |
2003PhRvD..67h4004F | Quantum radiation from a 5-dimensional rotating black hole | 2003-01-01 | 5 | 0.46 | 185 | ['-', '-', '-', '-', '-'] | [] | We study a massless scalar field propagating in the background of a five-dimensional rotating black hole. We show that in the Myers-Perry metric describing such a black hole the massless field equation allows the separation of variables. The obtained angular equation is a generalization of the equation for spheroidal functions. The radial equation is similar to the radial Teukolsky equation for the 4-dimensional Kerr metric. We use these results to quantize the massless scalar field in the space-time of the 5-dimensional rotating black hole and to derive expressions for energy and angular momentum fluxes from such a black hole. | [] | 2 | https://arxiv.org/pdf/gr-qc/0211055.pdf |
2002ApJ...578..787C | The Counterrotating Core and the Black Hole Mass of IC 1459 | 2002-01-01 | 14 | 0.52 | 185 | ['black hole physics', 'galaxies elliptical lenticular;cd', 'cd', 'galaxies', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'astrophysics'] | [] | The E3 giant elliptical galaxy IC 1459 is the prototypical galaxy with a fast counterrotating stellar core. We obtained one Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) long-slit spectrum along the major axis of this galaxy and Cerro Tololo Inter-American Observatory (CTIO) spectra along five position angles. The signal-to-noise ratio (S/N) of the ground-based data is such that also the higher order Gauss-Hermite moments (h<SUB>3</SUB>-h<SUB>6</SUB>) can be extracted reliably. We present self-consistent three-integral axisymmetric models of the stellar kinematics, obtained with Schwarzschild's numerical orbit superposition method. The available data allow us to study the dynamics of the kinematically decoupled core (KDC) in IC 1459, and we find that it consists of stars that are well separated from the rest of the galaxy in phase space. In particular, our study indicates that the stars in the KDC counterrotate in a disk on orbits that are close to circular. We estimate that the KDC mass is ~0.5% of the total galaxy mass or ~3×10<SUP>9</SUP> M<SUB>solar</SUB>. We estimate the central black hole (BH) mass M<SUB>BH</SUB> of IC 1459 independently from both its stellar and its gaseous kinematics. Although both tracers rule out models without a central BH, neither yields a particularly accurate determination of the BH mass. The main problem for the stellar dynamical modeling is the fact that the modest S/N of the STIS spectrum and the presence of strong gas emission lines preclude measuring the full line-of-sight velocity distribution (LOSVD) at HST resolution. The main problem for the gasdynamical modeling is that there is evidence that the gas motions are disturbed, possibly as a result of nongravitational forces acting on the gas. These complications probably explain why we find rather discrepant BH masses with the different methods. The stellar kinematics suggest that M<SUB>BH</SUB>=(2.6+/-1.1)×10<SUP>9</SUP> M<SUB>solar</SUB> (3 σ error). The gas kinematics suggests that M<SUB>BH</SUB>~3.5×10<SUP>8</SUP> M<SUB>solar</SUB> if the gas is assumed to rotate at the circular velocity in a thin disk. If the observed velocity dispersion of the gas is assumed to be gravitational, then M<SUB>BH</SUB> could be as high as ~1.0×10<SUP>9</SUP> M<SUB>solar</SUB>. These different estimates bracket the value M<SUB>BH</SUB>=(1.1+/-0.3)×10<SUP>9</SUP> M<SUB>solar</SUB> predicted by the M<SUB>BH</SUB>-σ relation. It will be an important goal for future studies to attempt comparisons of BH mass determinations from stellar and gaseous kinematics for other galaxies. This will assess the reliability of BH mass determinations with either technique. This is essential if one wants to interpret the correlation between the BH mass and other global galaxy parameters (e.g., velocity dispersion) and in particular the scatter in these correlations (believed to be only ~0.3 dex). Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. These observations are associated with proposal 7352. | [] | 8 | https://arxiv.org/pdf/astro-ph/0202155.pdf |
2019JCAP...01..037D | Primordial black holes from α-attractors | 2019-01-01 | 19 | 0.46 | 185 | ['-', '-', '-', '-'] | [] | We consider primordial black hole (PBH) production in inflationary α-attractors. We discuss two classes of models, namely models with a minimal polynomial superpotential as well as modulated chaotic ones that admit PBHs. We find that a significant amplification of the curvature power spectrum Script P<SUB>R</SUB> can be realized in this class of models with a moderate tuning of the potential parameters. We consistently examine the PBH formation during radiation and additionally during reheating eras where the background pressure is negligible. It is shown that basic features of the curvature power spectrum are explicitly related with the postinflationary cosmic evolution and that the PBH mass and abundance expressions are accordingly modified. PBHs in the mass range 10<SUP>-16</SUP>-10<SUP>-14</SUP> M<SUB>solar</SUB> can form with a cosmologically relevant abundance for a power spectrum peak Script P<SUB>R</SUB> ~ 10<SUP>-2</SUP> and large reheating temperature and, furthermore, for a moderate peak Script P<SUB>R</SUB> ~ 10<SUP>-5</SUP> and reheating temperature T<SUB>rh</SUB>~ 10<SUP>7</SUP> GeV, characteristic of the position of the power spectrum peak. Regarding the CMB observables, the α-attractor models utilized here to generate PBH in the low-mass region predict in general a smaller n<SUB>s</SUB> and larger r and α<SUB>s</SUB> parameter values compared to the conventional inflationary α-attractor models. | [] | 3 | https://arxiv.org/pdf/1805.09483.pdf |
2017LRR....20....6F | Black holes, hidden symmetries, and complete integrability | 2017-01-01 | 38 | 0.46 | 185 | ['-', '-', 'black hole physics', '-', '-', '-', '-', '-', '-', '-', '-', '-', '-'] | [] | The study of higher-dimensional black holes is a subject which has recently attracted vast interest. Perhaps one of the most surprising discoveries is a realization that the properties of higher-dimensional black holes with the spherical horizon topology and described by the Kerr–NUT–(A)dS metrics are very similar to the properties of the well known four-dimensional Kerr metric. This remarkable result stems from the existence of a single object called the principal tensor. In our review we discuss explicit and hidden symmetries of higher-dimensional Kerr–NUT–(A)dS black hole spacetimes. We start with discussion of the Killing and Killing–Yano objects representing explicit and hidden symmetries. We demonstrate that the principal tensor can be used as a "seed object" which generates all these symmetries. It determines the form of the geometry, as well as guarantees its remarkable properties, such as special algebraic type of the spacetime, complete integrability of geodesic motion, and separability of the Hamilton–Jacobi, Klein–Gordon, and Dirac equations. The review also contains a discussion of different applications of the developed formalism and its possible generalizations. | [] | 3 | https://arxiv.org/pdf/1705.05482.pdf |
2018JCAP...03..016F | Primordial black holes from inflation and non-Gaussianity | 2018-01-01 | 24 | 0.47 | 185 | ['-', '-', '-', '-'] | [] | Primordial black holes may owe their origin to the small-scale enhancement of the comoving curvature perturbation generated during inflation. Their mass fraction at formation is markedly sensitive to possible non-Gaussianities in such large, but rare fluctuations. We discuss a path-integral formulation which provides the exact mass fraction of primordial black holes at formation in the presence of non-Gaussianity. Through a couple of classes of models, one based on single-field inflation and the other on spectator fields, we show that restricting to a Gaussian statistics may lead to severe inaccuracies in the estimate of the mass fraction as well as on the clustering properties of the primordial black holes. | [] | 4 | https://arxiv.org/pdf/1801.09415.pdf |
2018MNRAS.475L..15G | A detached stellar-mass black hole candidate in the globular cluster NGC 3201 | 2018-01-01 | 31 | 0.55 | 184 | ['black hole physics', '-', 'techniques radial velocities', 'stars binaries spectroscopic', 'clusters globular', '-', '-'] | [] | As part of our massive spectroscopic survey of 25 Galactic globular clusters with MUSE, we performed multiple epoch observations of NGC 3201 with the aim of constraining the binary fraction. In this cluster, we found one curious star at the main-sequence turn-off with radial velocity variations of the order of 100 km s<SUP>- 1</SUP>, indicating the membership to a binary system with an unseen component since no other variations appear in the spectra. Using an adapted variant of the generalized Lomb-Scargle periodogram, we could calculate the orbital parameters and found the companion to be a detached stellar-mass black hole with a minimum mass of 4.36 ± 0.41 M<SUB>⊙</SUB>. The result is an important constraint for binary and black hole evolution models in globular clusters as well as in the context of gravitational wave sources. | [] | 10 | https://arxiv.org/pdf/1801.05642.pdf |
1997siad.conf..216B | Black Hole Hair: Twenty-Five Years After | 1997-01-01 | 7 | 0.46 | 184 | ['-', 'astrophysics', '-'] | [] | Originally regarded as forbidden, black hole ``hair'' are fields associated with a stationary black hole apart from the gravitational and electromagnetic ones. Several stable stationary black hole solutions with gauge or Skyrme field hair are known today within general relativity. We formulate here a ``no scalar--hair'' conjecture, and adduce some new theorems that almost establish it by ruling out - for all but a small parameter range - scalar field hair of spherical black holes in general relativity, whether the field be self--interacting, coupled to an Abelian gauge field, or nonminimally coupled to gravity. | [] | 1 | https://arxiv.org/pdf/gr-qc/9605059.pdf |
2010ApJ...711..284S | Galaxy Zoo: The Fundamentally Different Co-Evolution of Supermassive Black Holes and Their Early- and Late-Type Host Galaxies | 2010-01-01 | 24 | 0.53 | 184 | ['galaxies active', 'galaxies evolution', 'galaxies formation', 'galaxies seyfert', '-', '-'] | [] | We use data from the Sloan Digital Sky Survey and visual classifications of morphology from the Galaxy Zoo project to study black hole growth in the nearby universe (z < 0.05) and to break down the active galactic nucleus (AGN) host galaxy population by color, stellar mass, and morphology. We find that the black hole growth at luminosities L[{O III] >10<SUP>40</SUP> erg s<SUP>-1</SUP> in early- and late-type galaxies is fundamentally different. AGN host galaxies as a population have a broad range of stellar masses (10<SUP>10</SUP>-10<SUP>11</SUP> M <SUB>sun</SUB>), reside in the green valley of the color-mass diagram and their central black holes have median masses around 10<SUP>6.5</SUP> M <SUB>sun</SUB>. However, by comparing early- and late-type AGN host galaxies to their non-active counterparts, we find several key differences: in early-type galaxies, it is preferentially the galaxies with the least massive black holes that are growing, while in late-type galaxies, it is preferentially the most massive black holes that are growing. The duty cycle of AGNs in early-type galaxies is strongly peaked in the green valley below the low-mass end (10<SUP>10</SUP> M <SUB>sun</SUB>) of the red sequence at stellar masses where there is a steady supply of blue cloud progenitors. The duty cycle of AGNs in late-type galaxies on the other hand peaks in massive (10<SUP>11</SUP> M <SUB>sun</SUB>) green and red late-types which generally do not have a corresponding blue cloud population of similar mass. At high-Eddington ratios (L/L <SUB>Edd</SUB>>0.1), the only population with a substantial fraction of AGNs are the low-mass green valley early-type galaxies. Finally, the Milky Way likely resides in the "sweet spot" on the color-mass diagram where the AGN duty cycle of late-type galaxies is highest. We discuss the implications of these results for our understanding of the role of AGNs in the evolution of galaxies. <P />. | [] | 21 | https://arxiv.org/pdf/1001.3141.pdf |
2013MNRAS.433L...1S | Systematic investigation of the expected gravitational wave signal from supermassive black hole binaries in the pulsar timing band. | 2013-01-01 | 24 | 0.52 | 184 | ['black hole physics', 'gravitational waves', '-', 'galaxies evolution', '-', '-'] | [] | In this Letter, we carry out the first systematic investigation of the expected gravitational wave (GW) background generated by supermassive black hole (SMBH) binaries in the nHz frequency band accessible to pulsar timing arrays (PTAs). We take from the literature several estimates of the redshift-dependent galaxy mass function and of the fraction of close galaxy pairs to derive a wide range of galaxy merger rates. We then exploit empirical black hole-host relations to populate merging galaxies with SMBHs. The result of our procedure is a collection of a large number of phenomenological SMBH binary merger rates consistent with current observational constraints on the galaxy assembly at z < 1.5. For each merger rate we compute the associated GW signal, eventually producing a large set of estimates of the nHz GW background that we use to infer confidence intervals of its expected amplitude. When considering the most recent SMBH-host relations, accounting for overmassive black holes in brightest cluster galaxies, we find that the nominal 1σ interval of the expected GW signal is only a factor of 3-10 below current PTA limits, implying a non-negligible chance of detection in the next few years. | [] | 1 | https://arxiv.org/pdf/1211.5375.pdf |
2015MNRAS.454.2423A | A coordinate-independent characterization of a black hole shadow | 2015-01-01 | 22 | 0.47 | 184 | ['black hole physics', 'galaxy center', '-', '-', '-', '-'] | [] | A large international effort is under way to assess the presence of a shadow in the radio emission from the compact source at the centre of our Galaxy, Sagittarius A* (Sgr A*). If detected, this shadow would provide the first direct evidence of the existence of black holes and that Sgr A* is a supermassive black hole. In addition, the shape of the shadow could be used to learn about extreme gravity near the event horizon and to determine which theory of gravity better describes the observations. The mathematical description of the shadow has so far used a number of simplifying assumptions that are unlikely to be met by the real observational data. We here provide a general formalism to describe the shadow as an arbitrary polar curve expressed in terms of a Legendre expansion. Our formalism does not presume any knowledge of the properties of the shadow, e.g. the location of its centre, and offers a number of routes to characterize the distortions of the curve with respect to reference circles. These distortions can be implemented in a coordinate-independent manner by different teams analysing the same data. We show that the new formalism provides an accurate and robust description of noisy observational data, with smaller error variances when compared to previous approaches for the measurement of the distortion. | [] | 3 | https://arxiv.org/pdf/1503.09054.pdf |
2016JHEP...06..023L | The double copy: Bremsstrahlung and accelerating black holes | 2016-01-01 | 30 | 0.46 | 184 | ['scattering', '-', '-', '-'] | [] | Advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and Yang-Mills theory. A concrete example of this correspondence, which is known as the double copy, was recently intro-duced for the case of stationary Kerr-Schild spacetimes. Building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. The gravitational solution, which generalises the Schwarzschild solution, includes a non-trivial stress-energy tensor. This stress-energy tensor corresponds to a gauge theoretic current in the double copy. We interpret both of these sources as representing the radiative part of the field. Furthermore, in the simple example of Bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. Our results provide the strongest evidence yet that the classical double copy is directly related to the BCJ double copy for scattering amplitudes. | [] | 5 | https://arxiv.org/pdf/1603.05737.pdf |
2006PhRvD..74l2001L | Measuring coalescing massive binary black holes with gravitational waves: The impact of spin-induced precession | 2006-01-01 | 7 | 0.46 | 184 | ['-', '-', '-', '-', '-', 'perturbation theory', '-', 'waves', '-', 'astrophysics'] | [] | The coalescence of massive black holes generates gravitational waves (GWs) that will be measurable by space-based detectors such as LISA to large redshifts. The spins of a binary’s black holes have an important impact on its waveform. Specifically, geodetic and gravitomagnetic effects cause the spins to precess; this precession then modulates the waveform, adding periodic structure which encodes useful information about the binary’s members. Following pioneering work by Vecchio, we examine the impact upon GW measurements of including these precession-induced modulations in the waveform model. We find that the additional periodicity due to spin precession breaks degeneracies among certain parameters, greatly improving the accuracy with which they may be measured. In particular, mass measurements are improved tremendously, by one to several orders of magnitude. Localization of the source on the sky is also improved, though not as much—low redshift systems can be localized to an ellipse which is roughly 10-afew×10arcminutes in the long direction and a factor of 2 smaller in the short direction. Though not a drastic improvement relative to analyses which neglect spin precession, even modest gains in source localization will greatly facilitate searches for electromagnetic counterparts to GW events. Determination of distance to the source is likewise improved: We find that relative error in measured luminosity distance is commonly ∼0.1% 0.4% at z∼1. Finally, with the inclusion of precession, we find that the magnitude of the spins themselves can typically be determined for low redshift systems with an accuracy of about 0.1% 10%, depending on the spin value, allowing accurate surveys of mass and spin evolution over cosmic time. | [] | 2 | https://arxiv.org/pdf/gr-qc/0608062.pdf |
2011PhRvD..84h7501P | Slowly rotating black holes in alternative theories of gravity | 2011-01-01 | 25 | 0.46 | 183 | ['-', '-', '-', '-', '-', '-', '-'] | [] | We present, in closed analytic form, a general stationary, slowly rotating black hole, which is a solution to a large class of alternative theories of gravity in four dimensions. In these theories, the Einstein-Hilbert action is supplemented by all possible quadratic, algebraic curvature invariants coupled to a scalar field. The solution is found as a deformation of the Schwarzschild metric in general relativity. We explicitly derive the changes to the orbital frequency at the innermost stable circular orbit and at the light ring in closed form. These results could be useful when comparing general relativity against alternative theories by (say) measurements of x-ray emission in accretion disks, or by stellar motion around supermassive black holes. When gravitational-wave astronomy comes into force, strong constraints on the coupling parameters can in principle be made. | [] | 4 | https://arxiv.org/pdf/1109.3996.pdf |
2011ApJ...732...89K | Efficient Merger of Binary Supermassive Black Holes in Merging Galaxies | 2011-01-01 | 30 | 0.49 | 183 | ['galaxies evolution', 'galaxies interactions', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'gravitational waves', '-'] | [] | In spherical galaxies, binary supermassive black holes (SMBHs) have difficulty reaching sub-parsec separations due to depletion of stars on orbits that intersect the massive binary—the "final parsec problem." Galaxies that form via major mergers are substantially non-spherical, and it has been argued that the centrophilic orbits in triaxial galaxies might provide stars to the massive binary at a high enough rate to avoid stalling. Here we test that idea by carrying out fully self-consistent merger simulations of galaxies containing central SMBHs. We find hardening rates of the massive binaries that are indeed much higher than in spherical models and essentially independent of the number of particles used in the simulations. Binary eccentricities remain high throughout the simulations. Our results constitute a fully stellar-dynamical solution to the final parsec problem and imply a potentially high rate of events for low-frequency gravitational wave detectors like LISA. | [] | 3 | https://arxiv.org/pdf/1103.0272.pdf |
2004PhRvD..69l4022C | Towards a formalism for mapping the spacetimes of massive compact objects: Bumpy black holes and their orbits | 2004-01-01 | 6 | 0.46 | 183 | ['-', '-', '-', '-', 'perturbation theory', '-', 'waves', '-', '-', 'astrophysics'] | [] | Astronomical observations have established that extremely compact, massive objects are common in the Universe. It is generally accepted that these objects are, in all likelihood, black holes. As observational technology has improved, it has become possible to test this hypothesis in ever greater detail. In particular, it is or will be possible to measure the properties of orbits deep in the strong field of a black hole candidate (using x-ray timing or future gravitational-wave measurements) and to test whether they have the characteristics of black hole orbits in general relativity. Past work has shown that, in principle, such measurements can be used to map the spacetime of a massive compact object, testing in particular whether the object’s multipolar structure satisfies the rather strict constraints imposed by the black hole hypothesis. Performing such a test in practice requires that we be able to compare against objects with the “wrong” multipole structure. In this paper, we present tools for constructing the spacetimes of bumpy black holes: objects that are almost black holes, but that have some multipoles with the wrong value. In this first analysis, we focus on objects with no angular momentum. Generalization to bumpy Kerr black holes should be straightforward, albeit labor intensive. Our construction has two particularly desirable properties. First, the spacetimes which we present are good deep into the strong field of the object—we do not use a “large r” expansion (except to make contact with weak field intuition). Second, our spacetimes reduce to the exact black hole spacetimes of general relativity in a natural way, by dialing the “bumpiness” of the black hole to zero. We propose that bumpy black holes can be used as the foundation for a null experiment: if black hole candidates are indeed the black holes of general relativity, their bumpiness should be zero. By comparing the properties of orbits in a bumpy spacetime with those measured from an astrophysical source, observations should be able to test this hypothesis, stringently testing whether they are in fact the black holes of general relativity. | [] | 2 | https://arxiv.org/pdf/gr-qc/0402063.pdf |
2003CQGra..20L.205C | LETTER TO THE EDITOR: Will we observe black holes at the LHC? | 2003-01-01 | 4 | 0.46 | 183 | ['-', '-', '-'] | [] | The generalized uncertainty principle, motivated by string theory and non-commutative quantum mechanics, suggests significant modifications to the Hawking temperature and evaporation process of black holes. For extra-dimensional gravity with Planck scale O(TeV), this leads to important changes in the formation and detection of black holes at the large hadron collider. The number of particles produced in Hawking evaporation decreases substantially. The evaporation ends when the black-hole mass is Planck scale, leaving a remnant and a consequent missing energy of order TeV. Furthermore, the minimum energy for black-hole formation in collisions is increased, and could even be increased to such an extent that no black holes are formed at LHC energies. | [] | 3 | https://arxiv.org/pdf/hep-ph/0305223.pdf |
2015EPJC...75..175M | Black holes in modified gravity (MOG) | 2015-01-01 | 32 | 0.48 | 183 | ['-', '-', 'black hole physics', '-', 'quantum theory', '-', '-'] | [] | The field equations for scalar–tensor–vector gravity (STVG) or modified gravity (MOG) have a static, spherically symmetric black hole solution determined by the mass <inline-formula id="IEq1"><mml:math><mml:mi>M</mml:mi></mml:math></inline-formula> with two horizons. The strength of the gravitational constant is <inline-formula id="IEq2"><mml:math><mml:mrow><mml:mi>G</mml:mi><mml:mo>=</mml:mo><mml:msub><mml:mi>G</mml:mi><mml:mi>N</mml:mi></mml:msub><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mi mathvariant="italic">α</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:math></inline-formula> where <inline-formula id="IEq3"><mml:math><mml:mi mathvariant="italic">α</mml:mi></mml:math></inline-formula> is a parameter. A regular singularity-free MOG solution is derived using a nonlinear field dynamics for the repulsive gravitational field component and a reasonable physical energy-momentum tensor. The Kruskal–Szekeres completion of the MOG black hole solution is obtained. The Kerr-MOG black hole solution is determined by the mass <inline-formula id="IEq4"><mml:math><mml:mi>M</mml:mi></mml:math></inline-formula>, the parameter <inline-formula id="IEq5"><mml:math><mml:mi mathvariant="italic">α</mml:mi></mml:math></inline-formula> and the spin angular momentum <inline-formula id="IEq6"><mml:math><mml:mrow><mml:mi>J</mml:mi><mml:mo>=</mml:mo><mml:mi>M</mml:mi><mml:mi>a</mml:mi></mml:mrow></mml:math></inline-formula>. The equations of motion and the stability condition of a test particle orbiting the MOG black hole are derived, and the radius of the black hole photosphere and the shadows cast by the Schwarzschild-MOG and Kerr-MOG black holes are calculated. A traversable wormhole solution is constructed with a throat stabilized by the repulsive component of the gravitational field. | [] | 1 | https://arxiv.org/pdf/1412.5424.pdf |
2003JHEP...10..014H | Hawking radiation from a (4+n)-dimensional black hole: exact results for the Schwarzschild phase | 2003-01-01 | 7 | 0.46 | 183 | ['-', '-', 'astrophysics', '-', '-'] | [] | We start our analysis by deriving a master equation that describes the motion of a field with arbitrary spin s on a 3-brane embedded in a non-rotating, uncharged (4+n)-dimensional black hole background. By numerical analysis, we derive exact results for the greybody factors and emission rates for scalars, fermions and gauge bosons emitted directly on the brane, for all energy regimes and for an arbitrary number n of extra dimensions. The relative emissivities on the brane for different types of particles are computed and their dependence on the dimensionality of spacetime is demonstrated — we therefore conclude that both the amount and the type of radiation emitted can be used for the determination of n if the Hawking radiation from these black holes is observed. The emission of scalar modes in the bulk from the same black holes is also studied and the relative bulk-to-brane energy emissivity is accurately computed. We demonstrate that this quantity varies considerably with n but always remains smaller than unity — this provides firm support to earlier arguments made by Emparan, Horowitz and Myers. | [] | 2 | https://arxiv.org/pdf/hep-ph/0309054.pdf |
2023A&A...677A.145U | GA-NIFS: A massive black hole in a low-metallicity AGN at z ∼ 5.55 revealed by JWST/NIRSpec IFS | 2023-01-01 | 127 | 0.67 | 183 | ['galaxies active', 'galaxies photometry', 'galaxies quasars', 'ism abundances', '-'] | [] | We present rest-frame optical data of the compact z = 5.55 galaxy GS_3073 obtained using the integral field spectroscopy mode of the Near-InfraRed Spectrograph on board the James Webb Space Telescope. The galaxy's prominent broad components in several hydrogen and helium lines (though absent in the forbidden lines) and v detection of a large equivalent width of He IIλ4686, EW(He II) ∼20 Å, unambiguously identify it as an active galactic nucleus (AGN). We measured a gas phase metallicity of Z<SUB>gas</SUB>/Z<SUB>⊙</SUB>∼0.21<SUB>−0.04</SUB><SUP>+0.08</SUP> , which is lower than what has been inferred for both more luminous AGN at a similar redshift and lower redshift AGN. We empirically show that classical emission line ratio diagnostic diagrams cannot be used to distinguish between the primary ionisation source (AGN or star formation) for systems with such low metallicity, though different diagnostic diagrams involving He IIλ4686 prove very useful, independent of metallicity. We measured the central black hole mass to be log(M<SUB>BH</SUB>/M<SUB>⊙</SUB>)∼8.2 ± 0.4 based on the luminosity and width of the broad line region of the Hα emission. While this places GS_3073 at the lower end of known high-redshift black hole masses, it still appears to be overly massive when compared to its host galaxy's mass properties. We detected an outflow with a projected velocity ≳700 km s<SUP>−1</SUP> and inferred an ionised gas mass outflow rate of about 100 M<SUB>⊙</SUB> yr<SUP>−1</SUP>, suggesting that one billion years after the Big Bang, GS_3073 is able to enrich the intergalactic medium with metals. | [] | 23 | https://arxiv.org/pdf/2302.06647.pdf |
2009PhRvD..79d4023B | Turduckening black holes: An analytical and computational study | 2009-01-01 | 13 | 0.46 | 182 | ['-', '-', '-', '-', 'methods numerical', 'waves', '-'] | [] | We provide a detailed analysis of several aspects of the turduckening technique for evolving black holes. At the analytical level we study the constraint propagation for a family of formulations of Einstein’s field equations and identify under what conditions the turducken procedure is rigorously justified and under what conditions constraint violations will propagate to the outside of the black holes. We present high resolution spherically symmetric studies which verify our analytical predictions. Then we present three-dimensional simulations of single distorted black holes using different variations of the turduckening method and also the puncture method. We study the effect that these different methods have on the coordinate conditions, constraint violations, and extracted gravitational waves. We find that the waves agree up to small but nonvanishing differences, caused by escaping superluminal gauge modes. These differences become smaller with increasing detector location. | [] | 5 | https://arxiv.org/pdf/0809.3533.pdf |
2012PhRvD..86d3001B | New constraints on primordial black holes abundance from femtolensing of gamma-ray bursts | 2012-01-01 | 19 | 0.47 | 182 | ['-', '-', '-', '-', 'gamma rays', 'gamma rays', 'elementary particles', '-', '-', '-', '-'] | [] | The abundance of primordial black holes is currently significantly constrained in a wide range of masses. The weakest limits are established for the small mass objects where the small intensity of the associated physical phenomenon provides a challenge for current experiments. We used gamma-ray bursts with known redshifts detected by the Fermi Gamma-ray Burst Monitor (GBM) to search for the femtolensing effects caused by compact objects. The lack of femtolensing detection in the GBM data provides new evidence that primordial black holes in the mass range 10<SUP>17</SUP>-10<SUP>20</SUP>g do not constitute a major fraction of dark matter. | [] | 3 | https://arxiv.org/pdf/1204.2056.pdf |
2017MNRAS.464.2174B | N -body modelling of globular clusters: masses, mass-to-light ratios and intermediate-mass black holes | 2017-01-01 | 30 | 0.56 | 182 | ['stars luminosity function;mass function', 'stars luminosity function;mass function', 'clusters globular', 'clusters globular', '-'] | [] | We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well-observed clusters, we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of <M/L<SUB>V</SUB> > =1.98 ± 0.03, which agrees very well with the expected M/L ratio if the initial mass function (IMF) of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease in the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globular clusters are incompatible with the presence of intermediate-mass black holes (IMBHs) with more than a few thousand M<SUB>⊙</SUB> in them. The only clear exception is ω Cen, where the velocity dispersion profile provides strong evidence for the presence of a ∼40 000 M<SUB>⊙</SUB> IMBH in the centre of the cluster. | [] | 1 | https://arxiv.org/pdf/1609.08794.pdf |
1995ApJ...440..554Q | Models of Galaxies with Central Black Holes: Adiabatic Growth in Spherical Galaxies | 1995-01-01 | 12 | 0.51 | 182 | ['black hole physics', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'astrophysics'] | [] | We add black holes to nonrotating, spherical galaxy models, with the assumption that the black-hole growth is slow compared with the dynamical time but fast compared with the relaxation time. The outcome differs depending on whether the core of the initial galaxy does or does not resemble that of an isothermal sphere. For the isothermal case the previously known results are confirmed and sharpened: the black hole induces cusps in the density (ρ ∼ r<SUP>-3/2</SUP>) and velocity dispersion (υ<SUP>2</SUP> ∼ r<SUP>-1</SUP>), and a tangential anisotropy in the velocity distribution away from the center. For the nonisothermal case the induced density cusp is steeper, and the induced anisotropy is larger and penetrates right to the center. The cusp around the black hole is insensitive to anisotropy in the initial velocity distribution, and also to the origin of the black hole, unless its mass comes exclusively from the stars of lowest angular momentum, in which case the cusp is suppressed. We discuss the implications for the interpretation of evidence for massive black holes in galactic nuclei. | [] | 3 | https://arxiv.org/pdf/astro-ph/9407005.pdf |
2004ApJ...601..676V | Early Growth and Efficient Accretion of Massive Black Holes at High Redshift | 2004-01-01 | 3 | 0.47 | 182 | ['black hole physics', 'galaxies active', 'galaxies fundamental parameters', 'galaxies photometry', 'galaxies seyfert', 'galaxies quasars', 'astrophysics'] | [] | Black hole masses of the highest redshift quasars (4<~z<~6) are estimated using a previously presented scaling relationship, derived from reverberation mapping of nearby quasars, and compared with quasars at lower redshift. It is shown that the central black holes in luminous z>~4 quasars are very massive (>~10<SUP>9</SUP> M<SUB>solar</SUB>). It is argued that the mass estimates of the high-redshift quasars are not subject to larger uncertainties than those for nearby quasars. Specifically, the large masses are not overestimates, and the lack of similarly large black hole masses in the nearby universe does not rule out their existence at high redshift. However, active galactic nucleus host galaxies do not typically appear fully formed and/or evolved at these early epochs. This supports scenarios in which black holes build up mass very fast in a radiatively inefficient (or obscured) phase relative to the stars in their galaxies. In addition, upper envelopes of M<SUB>BH</SUB>~10<SUP>10</SUP> M<SUB>solar</SUB> and L<SUB>bol</SUB>~10<SUP>48</SUP> ergs s<SUP>-1</SUP> are observed at all redshifts. <P />Part of the observations reported here were obtained at the Multiple Mirror Telescope Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. | [] | 1 | https://arxiv.org/pdf/astro-ph/0309521.pdf |
1996PhRvD..54.6293B | STU black holes and string triality | 1996-01-01 | 13 | 0.46 | 182 | ['-', '-', '-', '-', '-', '-', '-', '-', '-'] | [] | We find double-extreme black holes associated with the special geometry of the Calabi-Yau moduli space with the prepotential F=STU. The area formula is STU-moduli independent and has [SL(2,Z)]<SUP>3</SUP> symmetry in space of charges. The dual version of this theory without a prepotential treats the dilaton S asymmetric vs T,U moduli. We display the dual relation between new (STU) black holes and stringy (S\|TU) black holes using a particular Sp(8,Z) transformation. The area formula of one theory equals that of the dual theory when expressed in terms of dual charges. We analyze the relation between (STU) black holes to string triality of black holes: (S\|TU), (T\|US), (U\|ST) solutions. In the democratic STU-symmetric version we find that all three S, T, and U duality symmetries are nonperturbative and mix electric and magnetic charges. | [] | 5 | https://arxiv.org/pdf/hep-th/9608059.pdf |
1998NuPhB.517..179S | Microscopic derivation of the Bekenstein-Hawking entropy formula for non-extremal black holes | 1998-01-01 | 6 | 0.46 | 182 | ['-', '-'] | [] | We derive the Bekenstein-Hawking entropy formula for four- and five-dimensional non-supersymmetric black holes (which include the Schwarzchild ones) by counting microscopic states. This is achieved by first showing that these black holes are U-dual to the three-dimensional black hole of Banados-Teitelboim-Zanelli and then counting microscopic states of the latter following Carlip's approach. Black holes higher than five dimensional are also considered. We discuss the connection of our approach to the D-brane picture. | [] | 2 | https://arxiv.org/pdf/hep-th/9711138.pdf |
2018PhRvD..97f4021T | Black hole shadow in an asymptotically flat, stationary, and axisymmetric spacetime: The Kerr-Newman and rotating regular black holes | 2018-01-01 | 29 | 0.47 | 182 | ['-'] | [] | The shadow of a black hole can be one of the strong observational evidences for stationary black holes. If we see shadows at the center of galaxies, we would say whether the observed compact objects are black holes. In this paper, we consider a formula for the contour of a shadow in an asymptotically-flat, stationary, and axisymmetric black hole spacetime. We show that the formula is useful for obtaining the contour of the shadow of several black holes such as the Kerr-Newman black hole and rotating regular black holes. Using the formula, we can obtain new examples of the contour of the shadow of rotating black holes if assumptions are satisfied. | [] | 1 | https://arxiv.org/pdf/1708.07427.pdf |
2018MNRAS.479.4391M | The cosmic merger rate of neutron stars and black holes | 2018-01-01 | 32 | 0.51 | 182 | ['-', 'black hole physics', 'gravitational waves', 'methods numerical', 'stars luminosity function;mass function', '-', '-', '-', '-'] | [] | Six gravitational wave detections have been reported so far, providing crucial insights on the merger rate of double compact objects. We investigate the cosmic merger rate of double neutron stars (DNSs), neutron star black hole binaries (NSBHs), and black hole binaries (BHBs) by means of population-synthesis simulations coupled with the Illustris cosmological simulation. We have performed six different simulations, considering different assumptions for the efficiency of common envelope (CE) ejection and exploring two distributions for the supernova (SN) kicks. The current BHB merger rate derived from our simulations spans from ∼150 to ∼240 Gpc<SUP>-3</SUP> yr<SUP>-1</SUP> and is only mildly dependent on CE efficiency. In contrast, the current merger rates of DNSs (ranging from ∼20 to ∼600 Gpc<SUP>-3</SUP> yr<SUP>-1</SUP>) and NSBHs (ranging from ∼10 to ∼100 Gpc<SUP>-3</SUP> yr<SUP>-1</SUP>) strongly depend on the assumptions on CE and natal kicks. The merger rate of DNSs is consistent with the one inferred from the detection of GW170817 only if a high efficiency of CE ejection and low-SN kicks (drawn from a Maxwellian distribution with one-dimensional root mean square σ = 15 km s<SUP>-1</SUP>) are assumed. | [] | 2 | https://arxiv.org/pdf/1806.04866.pdf |
2019PhRvD.100b3007Z | Highly spinning and aligned binary black hole merger in the Advanced LIGO first observing run | 2019-01-01 | 19 | 0.47 | 182 | ['-', '-', '-'] | [] | We report a new binary black hole merger in the publicly available LIGO first observing run (O1) data release. The event has a false alarm rate of one per six years in the detector-frame chirp-mass range M<SUP>det</SUP>∈[20 ,40 ]M<SUB>⊙</SUB> in a new independent analysis pipeline that we developed. Our best estimate of the probability that the event is of astrophysical origin is P<SUB>astro</SUB>∼0.71 . The estimated physical parameters of the event indicate that it is the merger of two massive black holes, M<SUP>det</SUP>=3 1<SUB>-3</SUB><SUP>+2</SUP>M<SUB>⊙</SUB> with an effective spin parameter, χ<SUB>eff</SUB>=0.8 1<SUB>-0.21</SUB><SUP>+0.15</SUP>, making this the most highly spinning merger reported to date. It is also among the two highest redshift mergers observed so far. The high aligned spin of the merger supports the hypothesis that merging binary black holes can be created by binary stellar evolution. | [] | 5 | https://arxiv.org/pdf/1902.10331.pdf |
2004ApJ...614L.117M | A Comparison of Intermediate-Mass Black Hole Candidate Ultraluminous X-Ray Sources and Stellar-Mass Black Holes | 2004-01-01 | 6 | 0.48 | 181 | ['accretion', 'accretion disks', 'black hole physics', 'galaxies stellar content', 'relativity', 'astronomy x rays', 'astrophysics'] | [] | Cool thermal emission components have recently been revealed in the X-ray spectra of a small number of ultraluminous X-ray sources (ULXs) with L<SUB>X</SUB>>=10<SUP>40</SUP> ergs s<SUP>-1</SUP> in nearby galaxies. These components can be well fitted with accretion disk models, with temperatures approximately 5-10 times lower than disk temperatures measured in stellar-mass Galactic black holes when observed in their brightest states. Because disk temperature is expected to fall with increasing black hole mass, and because the X-ray luminosity of these sources exceeds the Eddington limit for 10 M<SUB>solar</SUB> black holes (L<SUB>Edd</SUB>~=1.3×10<SUP>39</SUP> ergs s<SUP>-1</SUP>), these sources are extremely promising intermediate-mass black hole candidates. In this Letter, we directly compare the inferred disk temperatures and luminosities of these ULXs, with the disk temperatures and luminosities of a number of Galactic black holes. The sample of stellar-mass black holes was selected to include different orbital periods, companion types, inclinations, and column densities. These ULXs and stellar-mass black holes occupy distinct regions of a L<SUB>X</SUB>-kT diagram, suggesting these ULXs may harbor intermediate-mass black holes. We briefly discuss the important strengths and weaknesses of this interpretation. | [] | 3 | https://arxiv.org/pdf/astro-ph/0406656.pdf |
2008PhRvD..78d4002R | Final spin from the coalescence of two black holes | 2008-01-01 | 17 | 0.47 | 181 | ['-', '-', '-', '-', 'waves', 'methods numerical', '-', '-', '-', 'astrophysics'] | [] | We provide a compact analytic formula to compute the spin of the black hole produced by the coalescence of two black holes following a quasicircular inspiral. Without additional fits than those already available for binaries with aligned or antialigned spins, but with a minimal set of assumptions, we derive an expression that can model generic initial spin configurations and mass ratios, thus covering all of the 7-dimensional space of parameters. A comparison with simulations already shows very accurate agreements with all of the numerical data available to date, but we also suggest a number of ways in which our predictions can be further improved. | [] | 7 | https://arxiv.org/pdf/0712.3541.pdf |
2004PhRvD..70d1502G | New calculation of the mass fraction of primordial black holes | 2004-01-01 | 6 | 0.46 | 181 | ['-', '-', '-', 'cosmology miscellaneous', 'astrophysics'] | [] | We revisit the calculation of the abundance of primordial black holes (PBHs) formed from primordial density perturbations, using a formation criterion derived by Shibata and Sasaki which refers to a metric perturbation variable rather than the usual density contrast. We implement a derivation of the PBH abundance which uses peaks theory, and compare it to the standard calculation based on a Press-Schechter-like approach. We find that the two are in reasonable agreement if the Press-Schechter threshold is in the range Δ<SUB>th</SUB>≃0.3 to 0.5, but advocate use of the peaks theory expression which is based on a sounder theoretical footing. | [] | 4 | https://arxiv.org/pdf/astro-ph/0403181.pdf |
2004PhRvD..69j4025C | Gauss-Bonnet black holes in dS spaces | 2004-01-01 | 10 | 0.46 | 181 | ['-', '-', '-', '-', '-', '-'] | [] | We study the thermodynamic properties associated with the black hole horizon and cosmological horizon for the Gauss-Bonnet solution in de Sitter space. When the Gauss-Bonnet coefficient is positive, a locally stable small black hole appears in the case of spacetime dimension d=5, the stable small black hole disappears, and the Gauss-Bonnet black hole is always unstable quantum mechanically when d⩾6. On the other hand, the cosmological horizon is found to be always locally stable independent of the spacetime dimension. But the solution is not globally preferred; instead, the pure de Sitter space is globally preferred. When the Gauss-Bonnet coefficient is negative, there is a constraint on the value of the coefficient, beyond which the gravity theory is not well defined. As a result, there is not only an upper bound on the size of black hole horizon radius at which the black hole horizon and cosmological horizon coincide with each other, but also a lower bound depending on the Gauss-Bonnet coefficient and spacetime dimension. Within the physical phase space, the black hole horizon is always thermodynamically unstable and the cosmological horizon is always stable; furthermore, as in the case of the positive coefficient, the pure de Sitter space is still globally preferred. This result is consistent with the argument that the pure de Sitter space corresponds to an UV fixed point of dual field theory. | [] | 2 | https://arxiv.org/pdf/hep-th/0311020.pdf |
2008AJ....135.1968A | Weighing the Black Holes in z ≈ 2 Submillimeter-Emitting Galaxies Hosting Active Galactic Nuclei | 2008-01-01 | 11 | 0.48 | 181 | ['galaxies active', 'galaxies evolution', 'astronomy infrared', 'astronomy x rays', 'astrophysics'] | [] | We place direct observational constraints on the black-hole masses (M <SUB>BH</SUB>) of the cosmologically important z≈ 2 submillimeter-emitting galaxy (SMG; f <SUB>850 μm</SUB> gsim 4 mJy) population, and use measured host-galaxy masses to explore their evolutionary status. We employ the well-established virial black-hole mass estimator to "weigh" the black holes of a sample of z≈ 2 SMGs which exhibit broad Hα or Hβ emission. We find that the average black-hole mass and Eddington ratio (η = L <SUB>bol</SUB>/L <SUB>Edd</SUB>) of the lower-luminosity broad-line SMGs (L <SUB>X</SUB> ≈ 10<SUP>44</SUP> erg s<SUP>-1</SUP>) are log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) ≈ 8.0 and η≈ 0.2, respectively; by comparison, X-ray-luminous broad-line SMGs (L <SUB>X</SUB> ≈ 10<SUP>45</SUP> erg s<SUP>-1</SUP>) have log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) ≈ 8.4 and η≈ 0.6. The lower-luminosity broad-line SMGs lie in the same location of the L <SUB>X</SUB>-L <SUB>FIR</SUB> plane as more typical SMGs hosting X-ray-obscured active galactic nuclei and may be intrinsically similar systems, but orientated so that the rest-frame optical nucleus is visible. Under this hypothesis, we conclude that SMGs host black holes with log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) ≈7.8 we find supporting evidence from observations of local ultra-luminous infrared galaxies. Combining these black-hole mass constraints with measured host-galaxy masses, we find that the black holes in SMGs are gsim3 times smaller than those found in comparably massive normal galaxies in the local universe, albeit with considerable uncertainty, and gsim10 times smaller than those predicted for z≈ 2 luminous quasars and radio galaxies. These results imply that the growth of the black hole lags that of the host galaxy in SMGs, in stark contrast with that previously suggested for radio galaxies and luminous quasars at z≈ 2. On the basis of current host-galaxy mass constraints, we show that SMGs and their descendants cannot lie significantly above the locally defined M <SUB>BH</SUB>-M <SUB>GAL</SUB> relationship. We argue that the black holes in the z≈ 0 descendents of SMGs will have log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) ≈ 8.6, indicating that they only need to grow by a factor of ≈6 by the present day. We show that this amount of black-hole growth can be achieved within current estimates for the submillimeter-bright lifetime of SMGs, provided that the black holes can grow at rates close to the Eddington limit. | [] | 10 | https://arxiv.org/pdf/0803.0634.pdf |
2018JCAP...08..041B | Primordial black holes with an accurate QCD equation of state | 2018-01-01 | 29 | 0.49 | 181 | ['-', '-'] | [] | Making use of definitive new lattice computations of the Standard Model thermodynamics during the quantum chromodynamic (QCD) phase transition, we calculate the enhancement in the mass distribution of primordial black holes (PBHs) due to the softening of the equation of state. We find that the enhancement peaks at approximately 0.7M<SUB>solar</SUB>, with the formation rate increasing by at least two orders of magnitude due to the softening of the equation of state at this time, with a range of approximately 0.3M<SUB>solar</SUB><M<1.4M<SUB>solar</SUB> at full width half-maximum. PBH formation is increased by a smaller amount for PBHs with masses spanning a large range, 10<SUP>-3</SUP>M<SUB>solar</SUB><M<SUB>PBH</SUB><10<SUP>3</SUP>M<SUB>solar</SUB>, which includes the masses of the BHs that LIGO detected. The most significant source of uncertainty in the number of PBHs formed is now due to unknowns in the formation process, rather than from the phase transition. A near scale-invariant density power spectrum tuned to generate a population with mass and merger rate consistent with that detected by LIGO should also produce a much larger energy density of PBHs with solar mass. The existence of BHs below the Chandresekhar mass limit would be a smoking gun for a primordial origin and they could arguably constitute a significant fraction of the cold dark matter density. They also pose a challenge to inflationary model building which seek to produce the LIGO BHs without overproducing lighter PBHs. | [] | 4 | https://arxiv.org/pdf/1801.06138.pdf |
2018PhRvD..98h4036G | Spin orientations of merging black holes formed from the evolution of stellar binaries | 2018-01-01 | 24 | 0.5 | 181 | ['-', '-'] | [] | We study the expected spin misalignments of merging binary black holes formed in isolation by combining state-of-the-art population-synthesis models with efficient post-Newtonian evolutions, thus tracking sources from stellar formation to gravitational-wave detection. We present extensive predictions of the properties of sources detectable by both current and future interferometers. We account for the fact that detectors are more sensitive to spinning black-hole binaries with suitable spin orientations and find that this significantly impacts the population of sources detectable by LIGO, while this is not the case for third-generation detectors. We find that three formation pathways, differentiated by the order of core collapse and common-envelope phases, dominate the observed population, and that their relative importance critically depends on the recoils imparted to black holes at birth. Our models suggest that measurements of the "effective-spin" parameter χ<SUB>eff</SUB> will allow for powerful constraints. For instance, we find that the role of spin magnitudes and spin directions in χ<SUB>eff</SUB> can be largely disentangled, and that the symmetry of the effective-spin distribution is a robust indicator of the binary's formation history. Our predictions for individual spin directions and their precessional morphologies confirm and extend early toy models, while exploring substantially more realistic and broader sets of initial conditions. Our main conclusion is that specific subpopulations of black-hole binaries will exhibit distinctive precessional dynamics: these classes include (but are not limited to) sources where stellar tidal interactions act on sufficiently short timescales, and massive binaries produced in pulsational pair-instability supernovae. Measurements of black-hole spin orientations have enormous potential to constrain specific evolutionary processes in the lives of massive binary stars. | [] | 7 | https://arxiv.org/pdf/1808.02491.pdf |
2011ApJ...736..103B | The Spin of the Supermassive Black Hole in NGC 3783 | 2011-01-01 | 22 | 0.49 | 180 | ['accretion', 'accretion disks', 'black hole physics', 'galaxies active', 'galaxies seyfert', 'astronomy x rays', '-'] | [] | The Suzaku AGN Spin Survey is designed to determine the supermassive black hole spin in six nearby active galactic nuclei (AGNs) via deep Suzaku stares, thereby giving us our first glimpse of the local black hole spin distribution. Here, we present an analysis of the first target to be studied under the auspices of this Key Project, the Seyfert galaxy NGC 3783. Despite complexity in the spectrum arising from a multi-component warm absorber, we detect and study relativistic reflection from the inner accretion disk. Assuming that the X-ray reflection is from the surface of a flat disk around a Kerr black hole, and that no X-ray reflection occurs within the general relativistic radius of marginal stability, we determine a lower limit on the black hole spin of a >= 0.88 (99% confidence). We examine the robustness of this result to the assumption of the analysis and present a brief discussion of spin-related selection biases that might affect flux-limited samples of AGNs. | [] | 12 | https://arxiv.org/pdf/1104.1172.pdf |
2013PhRvL.110u1301G | Loop Quantization of the Schwarzschild Black Hole | 2013-01-01 | 28 | 0.46 | 180 | ['-', '-', '-', '-', '-', '-', '-', '-', '-'] | [] | We quantize spherically symmetric vacuum gravity without gauge fixing the diffeomorphism constraint. Through a rescaling, we make the algebra of Hamiltonian constraints Abelian, and therefore the constraint algebra is a true Lie algebra. This allows the completion of the Dirac quantization procedure using loop quantum gravity techniques. We can construct explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. New observables living in the bulk appear at the quantum level (analogous to spin in quantum mechanics) that are not present at the classical level and are associated with the discrete nature of the spin network states of loop quantum gravity. The resulting quantum space-times resolve the singularity present in the classical theory inside black holes. | [] | 2 | https://arxiv.org/pdf/1302.5265.pdf |
2018ApJ...856....6D | Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IX. 10 New Observations of Reverberation Mapping and Shortened Hβ Lags | 2018-01-01 | 42 | 0.56 | 180 | ['accretion', 'accretion disks', 'galaxies active', 'galaxies nuclei', 'galaxies quasars', '-'] | [] | As one paper in a series reporting on a large reverberation mapping campaign of super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs), we present the results of 10 SEAMBHs monitored spectroscopically during 2015-2017. Six of them are observed for the first time, and have generally higher 5100 Å luminosities than the SEAMBHs monitored in our campaign from 2012 to 2015; the remaining four are repeat observations to check if their previous lags change. Similar to the previous SEAMBHs, the Hβ time lags of the newly observed objects are shorter than the values predicted by the canonical R <SUB>Hβ </SUB>-L <SUB>5100</SUB> relation of sub-Eddington AGNs, by factors of ∼2-6, depending on the accretion rate. The four previously observed objects have lags consistent with previous measurements. We provide linear regressions for the R <SUB>Hβ </SUB>-L <SUB>5100</SUB> relation, solely for the SEAMBH sample and for low-accretion AGNs. We find that the relative strength of Fe II and the profile of the Hβ emission line can be used as proxies of accretion rate, showing that the shortening of Hβ lags depends on accretion rates. The recent SDSS-RM discovery of shortened Hβ lags in AGNs with low accretion rates provides compelling evidence for retrograde accretion onto the black hole. These evidences show that the canonical R <SUB>Hβ </SUB>-L <SUB>5100</SUB> relation holds only in AGNs with moderate accretion rates. At low accretion rates, it should be revised to include the effects of black hole spin, whereas the accretion rate itself becomes a key factor in the regime of high accretion rates. | [] | 14 | https://arxiv.org/pdf/1802.03022.pdf |
2008JHEP...05..003M | Black holes and quantum gravity at the LHC | 2008-01-01 | 17 | 0.46 | 180 | ['-'] | [] | We argue that the highly studied black hole signatures based on thermal multiparticle final states are very unlikely and only occur in a very limited parameter regime if at all. However, we show that if the higher-dimensional quantum gravity scale is low, it should be possible to study quantum gravity in the context of higher dimensions through detailed compositeness-type searches. | [] | 2 | https://arxiv.org/pdf/0708.3017.pdf |
2008PhRvD..77b6004B | Estimating the final spin of a binary black hole coalescence | 2008-01-01 | 9 | 0.47 | 180 | ['-', '-', '-', '-', 'methods numerical', '-', '-', 'astrophysics', '-'] | [] | We present a straightforward approach for estimating the final black hole spin of a binary black hole coalescence with arbitrary initial masses and spins. Making some simple assumptions, we estimate the final angular momentum to be the sum of the individual spins plus the orbital angular momentum of a test particle orbiting at the last stable orbit around a Kerr black hole with a spin parameter of the final black hole. The formula we obtain is able to reproduce with reasonable accuracy the results from available numerical simulations, but, more importantly, it can be used to investigate what configurations might give rise to interesting dynamics. In particular, we discuss scenarios which might give rise to a flip in the direction of the total angular momentum of the system. By studying the dependence of the final spin upon the mass ratio and initial spins, we find that our simple approach suggests that it is not possible to spin-up a black hole to extremal values through merger scenarios irrespective of the mass ratio of the objects involved. | [] | 3 | https://arxiv.org/pdf/0709.3839.pdf |
2021JCAP...03..068H | Two populations of LIGO-Virgo black holes | 2021-01-01 | 24 | 0.5 | 180 | ['-', '-', '-', '-', '-', '-', '-'] | [] | We analyse the LIGO-Virgo data, including the recently released GWTC-2dataset, to test a hypothesis that the data contains more than one population of black holes. We perform a maximum likelihood analysis including a population of astrophysical black holes with a truncated power-law mass function whose merger rate follows from star formation rate, and a population of primordial black holes for which we consider log-normal and critical collapse mass functions. We find that primordial black holes alone are strongly disfavoured by the data, while the best fit is obtained for the template combining astrophysical and primordial merger rates. Alternatively, the data may hint towards two different astrophysical black hole populations. We also update the constraints on primordial black hole abundance from LIGO-Virgo observations finding that in the 2-400 mass range they must comprise less than 0.2% of dark matter. | [] | 4 | https://arxiv.org/pdf/2012.02786.pdf |
2013LRR....16....8K | Classification of Near-Horizon Geometries of Extremal Black Holes | 2013-01-01 | 43 | 0.46 | 180 | ['-', '-', 'black hole physics', '-', '-', '-', '-'] | [] | Any spacetime containing a degenerate Killing horizon, such as an extremal black hole, possesses a well-defined notion of a near-horizon geometry. We review such near-horizon geometry solutions in a variety of dimensions and theories in a unified manner. We discuss various general results including horizon topology and near-horizon symmetry enhancement. We also discuss the status of the classification of near-horizon geometries in theories ranging from vacuum gravity to Einstein-Maxwell theory and supergravity theories. Finally, we discuss applications to the classification of extremal black holes and various related topics. Several new results are presented and open problems are highlighted throughout. | [] | 2 | https://arxiv.org/pdf/1306.2517.pdf |
2002PThPS.148..307T | Classical Black Hole Evaporation in Randall-Sundrum Infinite Braneworld | 2002-01-01 | 5 | 0.46 | 180 | ['-', '-'] | [] | After the gravity induced on the brane in the Randall-Sundrum (RS) infinite braneworld is briefly reviewed, we discuss the possibility that black holes evaporate as a result of classical evolution in this model based on the AdS/CFT correspondence. If this possibility is really the case, the existence of long-lived solar mass black holes will give the strongest constraint on the bulk curvature radius. At the same time, we can propose a new method to simulate the evaporation of a 4D black hole due to the Hawking radiation as a 5D process. | [] | 1 | https://arxiv.org/pdf/gr-qc/0203082.pdf |
2006JHEP...04..036K | Supersymmetric multi-charge AdS<SUB>5</SUB> black holes | 2006-01-01 | 4 | 0.45 | 180 | ['-'] | [] | A new supersymmetric, asymptotically anti-de Sitter, black hole solution of five-dimensional U(1)<SUP>3</SUP> gauged supergravity is presented. All known examples of such black holes arise as special cases of this solution, which is characterized by three charges and two angular momenta, with one constraint relating these five quantities. Analagous solutions of U(1)<SUP>n</SUP> gauged supergravity are also presented. | [] | 3 | https://arxiv.org/pdf/hep-th/0601156.pdf |
2021Sci...371.1046M | Cygnus X-1 contains a 21-solar mass black hole—Implications for massive star winds | 2021-01-01 | 68 | 0.62 | 180 | ['-', '-'] | [] | The evolution of massive stars is influenced by the mass lost to stellar winds over their lifetimes. These winds limit the masses of the stellar remnants (such as black holes) that the stars ultimately produce. We used radio astrometry to refine the distance to the black hole x-ray binary Cygnus X-1, which we found to be 2.22<SUB>-0.17</SUB><SUP>+0.18</SUP> kiloparsecs. When combined with archival optical data, this implies a black hole mass of 21.2 ± 2.2 solar masses, which is higher than previous measurements. The formation of such a high-mass black hole in a high-metallicity system (within the Milky Way) constrains wind mass loss from massive stars. | [] | 26 | https://arxiv.org/pdf/2102.09091.pdf |
2019Natur.573..381M | Nine-hour X-ray quasi-periodic eruptions from a low-mass black hole galactic nucleus | 2019-01-01 | 88 | 0.63 | 180 | ['-', '-'] | [] | In the past two decades, high-amplitude electromagnetic outbursts have been detected from dormant galaxies and often attributed to the tidal disruption of a star by the central black hole<SUP>1,2</SUP>. X-ray emission from the Seyfert 2 galaxy GSN 069 (2MASX J01190869-3411305) at a redshift of z = 0.018 was first detected in July 2010 and implies an X-ray brightening by a factor of more than 240 over ROSAT observations performed 16 years earlier<SUP>3,4</SUP>. The emission has smoothly decayed over time since 2010, possibly indicating a long-lived tidal disruption event<SUP>5</SUP>. The X-ray spectrum is ultra-soft and can be described by accretion disk emission with luminosity proportional to the fourth power of the disk temperature during long-term evolution. Here we report observations of quasi-periodic X-ray eruptions from the nucleus of GSN 069 over the course of 54 days, from December 2018 onwards. During these eruptions, the X-ray count rate increases by up to two orders of magnitude with an event duration of just over an hour and a recurrence time of about nine hours. These eruptions are associated with fast spectral transitions between a cold and a warm phase in the accretion flow around a low-mass black hole (of approximately 4 × 10<SUP>5</SUP> solar masses) with peak X-ray luminosity of about 5 × 10<SUP>42</SUP> erg per second. The warm phase has kT (where T is the temperature and k is the Boltzmann constant) of about 120 electronvolts, reminiscent of the typical soft-X-ray excess, an almost universal thermal-like feature in the X-ray spectra of luminous active nuclei<SUP>6-8</SUP>. If the observed properties are not unique to GSN 069, and assuming standard scaling of timescales with black hole mass and accretion properties, typical active galactic nuclei with higher-mass black holes can be expected to exhibit high-amplitude optical to X-ray variability on timescales as short as months or years<SUP>9</SUP>. | [] | 14 | https://arxiv.org/pdf/1909.04693.pdf |
2016MNRAS.461.3760H | Circularization of tidally disrupted stars around spinning supermassive black holes | 2016-01-01 | 36 | 0.5 | 179 | ['accretion', 'accretion disks', 'black hole physics', 'gravitational waves', 'hydrodynamics', '-', '-'] | [] | We study the circularization of tidally disrupted stars on bound orbits around spinning supermassive black holes by performing 3D smoothed particle hydrodynamic simulations with post-Newtonian corrections. Our simulations reveal that debris circularization depends sensitively on the efficiency of radiative cooling. There are two stages in debris circularization if radiative cooling is inefficient: first, the stellar debris streams self-intersect due to relativistic apsidal precession; shocks at the intersection points thermalize orbital energy and the debris forms a geometrically thick, ring-like structure around the black hole. The ring rapidly spreads via viscous diffusion, leading to the formation of a geometrically thick accretion disc. In contrast, if radiative cooling is efficient, the stellar debris circularizes due to self-intersection shocks and forms a geometrically thin ring-like structure. In this case, the dissipated energy can be emitted during debris circularization as a precursor to the subsequent tidal disruption flare. The circularization time-scale is remarkably long in the radiatively efficient cooling case, and is also sensitive to black hole spin. Specifically, Lense-Thirring torques cause dynamically important nodal precession, which significantly delays debris circularization. On the other hand, nodal precession is too slow to produce observable signatures in the radiatively inefficient case. Since the stellar debris is optically thick and its photon diffusion time is likely longer than the time-scale of shock heating, our inefficient cooling scenario is more generally applicable in eccentric tidal disruption events (TDEs). However, in parabolic TDEs for M<SUB>BH</SUB> ≳ 2 × 10<SUP>6</SUP> M<SUB>⊙</SUB>, the spin-sensitive behaviour associated with efficient cooling may be realized. | [] | 3 | https://arxiv.org/pdf/1501.05207.pdf |
1996PhLB..381..423B | Macroscopic and microscopic entropy of near-extremal spinning black holes | 1996-01-01 | 6 | 0.45 | 179 | ['-'] | [] | A seven-parameter family of five-dimensional black hole solutions depending on mass, two angular momenta, three charges and the asymptotic value of a scalar field is constructed. The entropy is computed as a function of these parameters both from the Bekenstein-Hawking formula and from the degeneracies of the corresponding D-brane states in string theory. The expressions agree at and to leading order away from extremality. | [] | 6 | https://arxiv.org/pdf/hep-th/9603078.pdf |
2003PhRvD..67j3009B | Gravitational lensing by a charged black hole of string theory | 2003-01-01 | 7 | 0.46 | 179 | ['-', '-', '-', '-', '-', 'astrophysics', '-'] | [] | We study gravitational lensing by the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) charged black hole of heterotic string theory and obtain the angular position and magnification of the relativistic images. Modeling the supermassive central object of the galaxy as a GMGHS black hole, we estimate the numerical values of different strong-lensing parameters. We find that there is no significant string effect present in the lensing observables in the strong-gravity scenario. | [] | 1 | https://arxiv.org/pdf/gr-qc/0306016.pdf |
2003NuPhS.124..103C | Black hole remnants and dark matter | 2003-01-01 | 10 | 0.45 | 179 | ['-'] | [] | We argue that, when the gravity effect is included, the generalized uncertainty principle (CUP) may prevent black holes from total evaporation in a similar way that the standard uncertainty principle prevents the hydrogen atom from total collapse. Specifically we invoke the GUP to obtain a modified Hawking temperature, which indicates that there should exist non-radiating remnants (BHR) of about Planck mass. BHRs are an attractive candidate for cold dark matter. We investigate an alternative cosmology in which primordial BHRs are the primary source of dark matter. <P />Work partially funded by NASA, Grant NAS8-39225 | [] | 2 | https://arxiv.org/pdf/gr-qc/0205106.pdf |
1995CQGra..12.1081L | Two-dimensional black holes and planar general relativity | 1995-01-01 | 7 | 0.46 | 179 | ['-'] | [] | The Einstein-Hilbert action with a cosmological term is used to derive a new action in 1+1 spacetime dimensions. It is shown that the two-dimensional theory is equivalent to planar symmetry in General Relativity. The two-dimensional theory admits black holes and free dilatons, and has a structure similar to two-dimensional string theories. Since by construction these solutions also solve Einstein's equations, such a theory can bring two-dimensional results into the four-dimensional real world. In particular the two-dimensional black hole is also a black hole in General Relativity. | [] | 1 | https://arxiv.org/pdf/gr-qc/9407024.pdf |
2010JHEP...10..027G | Holography of dyonic dilaton black branes | 2010-01-01 | 15 | 0.46 | 179 | ['-', 'black hole physics', '-', '-', '-'] | [] | We study black branes carrying both electric and magnetic charges in Einstein-Maxwell theory coupled to a dilaton-axion in asymptotically anti de Sitter space. After reviewing and extending earlier results for the case of electrically charged branes, we characterise the thermodynamics of magnetically charged branes. We then focus on dyonic branes in theories which enjoy an SL(2 ,R) electric-magnetic duality. Using SL(2 ,R), we are able to generate solutions with arbitrary charges starting with the electrically charged solution, and also calculate transport coefficients. These solutions all exhibit a Lifshitz-like near-horizon geometry. The system behaves as expected for a charged fluid in a magnetic field, with non-vanishing Hall conductance and vanishing DC longitudinal conductivity at low temperatures. Its response is characterised by a cyclotron resonance at a frequency proportional to the magnetic field, for small magnetic fields. Interestingly, the DC Hall conductance is related to the attractor value of the axion. We also study the attractor flows of the dilaton-axion, both in cases with and without an additional modular-invariant scalar potential. The flows exhibit intricate behaviour related to the duality symmetry. Finally, we briefly discuss attractor flows in more general dilaton-axion theories which do not enjoy SL(2 ,R) symmetry. | [] | 6 | https://arxiv.org/pdf/1007.2490.pdf |
2007CQGra..24S..59P | Reducing orbital eccentricity in binary black hole simulations | 2007-01-01 | 5 | 0.46 | 179 | ['-'] | [] | Binary black hole simulations starting from quasi-circular (i.e., zero radial velocity) initial data have orbits with small but nonzero orbital eccentricities. In this paper, the quasi-equilibrium initial-data method is extended to allow nonzero radial velocities to be specified in binary black hole initial data. New low-eccentricity initial data are obtained by adjusting the orbital frequency and radial velocities to minimize the orbital eccentricity, and the resulting (~5 orbit) evolutions are compared with those of quasi-circular initial data. Evolutions of the quasi-circular data clearly show eccentric orbits, with eccentricity that decays over time. The precise decay rate depends on the definition of eccentricity; if defined in terms of variations in the orbital frequency, the decay rate agrees well with the prediction of Peters (1964 Phys. Rev. 136 1224 32). The gravitational waveforms, which contain ~8 cycles in the dominant l = m = 2 mode, are largely unaffected by the eccentricity of the quasi-circular initial data. The overlap between the dominant mode in the quasi-circular evolution and the same mode in the low-eccentricity evolution is about 0.99. | [] | 6 | https://arxiv.org/pdf/gr-qc/0702106.pdf |
2003PhRvD..67f4025I | Rotating black holes at future colliders: Greybody factors for brane fields | 2003-01-01 | 7 | 0.46 | 179 | ['-', '-', '-', '-', '-', '-', '-', '-'] | [] | We study theoretical aspects of rotating black hole production and evaporation in extra dimension scenarios with TeV scale gravity, within the mass range in which the higher dimensional Kerr solution provides a good description. We evaluate the production cross section of black holes, taking their angular momenta into account. We find that it becomes larger than the Schwarzschild radius squared, which is conventionally utilized in the literature, and our result nicely agrees with the recent numerical study by Yoshino and Nambu within a few percent error for the higher dimensional case. In the same approximation used to obtain the above result, we find that the production cross section becomes larger for a black hole with larger angular momentum. Second, we derive the generalized Teukolsky equation for spin 0, 1/2, and 1 brane fields in higher dimensional Kerr geometry and explicitly show that it is separable in any dimensions. For a five-dimensional (Randall-Sundrum) black hole, we obtain analytic formulas for the greybody factors in the low frequency expansion and we present the power spectra of the Hawking radiation as well as their angular dependence. The phenomenological implications of our results are briefly sketched. | [] | 3 | https://arxiv.org/pdf/hep-th/0212108.pdf |
2012ApJ...755...51N | Circumbinary Magnetohydrodynamic Accretion into Inspiraling Binary Black Holes | 2012-01-01 | 22 | 0.51 | 179 | ['accretion', 'accretion disks', 'black hole physics', 'galaxies nuclei', 'mhd', '-', '-', '-'] | [] | We have simulated the magnetohydrodynamic evolution of a circumbinary disk surrounding an equal-mass binary comprising two non-spinning black holes during the period in which the disk inflow time is comparable to the binary evolution time due to gravitational radiation. Both the changing spacetime and the binary orbital evolution are described by an innovative technique utilizing high-order post-Newtonian approximations. Prior to the beginning of the inspiral, the structure of the circumbinary disk is predicted well by extrapolation from Newtonian results: a gap of roughly two binary separation radii is cleared, and matter piles up at the outer edge of this gap as inflow is retarded by torques exerted by the binary; the accretion rate is roughly half its value at large radius. During inspiral, the inner edge of the disk initially moves inward in coordination with the shrinking binary, but—as the orbital evolution accelerates—the inward motion of the disk edge falls behind the rate of binary compression. In this stage, the binary torque falls substantially, but the accretion rate decreases by only 10%-20%. When the binary separation is tens of gravitational radii, the rest-mass efficiency of disk radiation is a few percent, suggesting that supermassive binary black holes could be very luminous at this stage of their evolution. Inner disk heating is modulated at a beat frequency comparable to the binary orbital frequency. However, a disk with sufficient surface density to be luminous may be optically thick, suppressing periodic modulation of the luminosity. | [] | 7 | https://arxiv.org/pdf/1204.1073.pdf |
2015ApJ...804..148V | The Case for Supercritical Accretion onto Massive Black Holes at High Redshift | 2015-01-01 | 30 | 0.5 | 179 | ['accretion', 'accretion disks', 'galaxies photometry', 'galaxies quasars', '-', '-', '-'] | [] | Short-lived intermittent phases of super-critical (super-Eddington) growth, coupled with star formation via positive feedback, may account for early growth of massive black holes (MBH) and coevolution with their host spheroids. We estimate the possible growth rates and duty cycles of these episodes, both assuming slim accretion disk solutions and adopting the results of recent numerical simulations. The angular momentum of gas joining the accretion disk determines the length of the accretion episodes and the final mass that an MBH can reach. The latter can be related to the gas velocity dispersion and, in galaxies with low-angular momentum gas, the MBH can reach a higher mass. When the host galaxy is able to sustain inflow rates at 1-100 {{M}<SUB>⊙ </SUB>} y{{r}<SUP>-1</SUP>}, replenishing and circulation lead to a sequence of short (∼ {{10}<SUP>4</SUP>}-{{10}<SUP>7</SUP>} yr), heavily obscured accretion episodes that increase the growth rates, with respect to an Eddington-limited case, by several orders of magnitude. Our model predicts that the ratio of the MBH accretion rate-to-star formation rate is 10<SUP>-2</SUP> or higher, leading, at early epochs, to a ratio of MBH-to-stellar mass that is higher than the “canonical” value of ∼ {{10}<SUP>-3</SUP>}, which is in agreement with current observations. Our model makes specific predictions that long-lived super-critical accretion occurs only in galaxies with copious low-angular momentum gas, and, in this case, the MBH is more massive at a fixed velocity dispersion. | [] | 3 | https://arxiv.org/pdf/1401.3513.pdf |
2016MNRAS.455.1665B | European Pulsar Timing Array limits on continuous gravitational waves from individual supermassive black hole binaries | 2016-01-01 | 30 | 0.5 | 179 | ['black hole physics', 'gravitational waves', '-', '-', '-', '-', '-'] | [] | We have searched for continuous gravitational wave (CGW) signals produced by individually resolvable, circular supermassive black hole binaries (SMBHBs) in the latest European Pulsar Timing Array (EPTA) data set, which consists of ultraprecise timing data on 41-ms pulsars. We develop frequentist and Bayesian detection algorithms to search both for monochromatic and frequency-evolving systems. None of the adopted algorithms show evidence for the presence of such a CGW signal, indicating that the data are best described by pulsar and radiometer noise only. Depending on the adopted detection algorithm, the 95 per cent upper limit on the sky-averaged strain amplitude lies in the range 6 × 10<SUP>-15</SUP> < A < 1.5 × 10<SUP>-14</SUP> at 5 nHz < f < 7 nHz. This limit varies by a factor of five, depending on the assumed source position and the most constraining limit is achieved towards the positions of the most sensitive pulsars in the timing array. The most robust upper limit - obtained via a full Bayesian analysis searching simultaneously over the signal and pulsar noise on the subset of ours six best pulsars - is A ≈ 10<SUP>-14</SUP>. These limits, the most stringent to date at f < 10 nHz, exclude the presence of sub-centiparsec binaries with chirp mass M_c>10^9 M_{⊙} out to a distance of about 25 Mpc, and with M_c>10^{10} M_{⊙} out to a distance of about 1Gpc (z ≈ 0.2). We show that state-of-the-art SMBHB population models predict <1 per cent probability of detecting a CGW with the current EPTA data set, consistent with the reported non-detection. We stress, however, that PTA limits on individual CGW have improved by almost an order of magnitude in the last five years. The continuing advances in pulsar timing data acquisition and analysis techniques will allow for strong astrophysical constraints on the population of nearby SMBHBs in the coming years. | [] | 36 | https://arxiv.org/pdf/1509.02165.pdf |
2010MNRAS.407.1946D | Compact binaries in star clusters - I. Black hole binaries inside globular clusters | 2010-01-01 | 26 | 0.47 | 179 | ['gravitational waves', 'stars binaries close', 'clusters globular', '-', '-'] | [] | We study the compact binary population in star clusters, focusing on binaries containing black holes, using a self-consistent Monte Carlo treatment of dynamics and full stellar evolution. We find that the black holes experience strong mass segregation and become centrally concentrated. In the core the black holes interact strongly with each other and black hole-black hole binaries are formed very efficiently. The strong interactions, however, also destroy or eject the black hole-black hole binaries. We find no black hole-black hole mergers within our simulations but produce many hard escapers that will merge in the Galactic field within a Hubble time. We also find several highly eccentric black hole-black hole binaries that are potential Laser Interferometer Space Antenna (LISA) sources, suggesting that star clusters are interesting targets for space-based detectors. We conclude that star clusters must be taken into account when predicting compact binary population statistics. | [] | 4 | https://arxiv.org/pdf/0910.0546.pdf |
2021JCAP...03..053P | Gravitational waves from a universe filled with primordial black holes | 2021-01-01 | 43 | 0.47 | 179 | ['-', '-', '-', '-', '-'] | [] | Ultra-light primordial black holes, with masses m<SUP>PBH</SUP> < 10<SUP>9</SUP>g, evaporate before big-bang nucleosynthesis and can therefore not be directly constrained. They can however be so abundant that they dominate the universe content for a transient period (before reheating the universe via Hawking evaporation). If this happens, they support large cosmological fluctuations at small scales, which in turn induce the production of gravitational waves through second-order effects. Contrary to the primordial black holes, those gravitational waves survive after evaporation, and can therefore be used to constrain such scenarios. In this work, we show that for induced gravitational waves not to lead to a backreaction problem, the relative abundance of black holes at formation, denoted Ω<SUB>PBH,f</SUB>, should be such that Ω<SUB>PBH,f</SUB> < 10<SUP>-4</SUP>(m<SUP>PBH</SUP>/10<SUP>9</SUP>g)<SUP>-1/4</SUP>. In particular, scenarios where primordial black holes dominate right upon their formation time are all excluded (given that m<SUP>PBH</SUP> > 10 g for inflation to proceed at ρ<SUP>1/4</SUP> < 10<SUP>16</SUP> GeV). This sets the first constraints on ultra-light primordial black holes. | [] | 3 | https://arxiv.org/pdf/2010.11573.pdf |
1999ApJ...514..164R | X-Ray Iron Line Reverberation from Black Hole Accretion Disks | 1999-01-01 | 12 | 0.48 | 178 | ['accretion', 'accretion disks', 'black hole physics', 'galaxies active', 'galaxies seyfert', 'astronomy x rays', 'accretion', 'accretion disks', 'black hole physics', 'galaxies active', 'galaxies seyfert', 'astronomy x rays', 'astrophysics'] | [] | The relativistically broad X-ray iron line seen in many active galactic nucleus (AGN) spectra is thought to originate from the central regions of the putative black hole accretion disk. Both the line profile and strength will vary in response to rapid variability of the primary X-ray continuum source. The temporal response of the line contains information on the accretion disk structure, the X-ray source geometry, and the spin of the black hole. Since the X-ray source will have a size comparable with the fluorescing region of the accretion disk, the general reverberation problem is not invertible. However, progress can be made, since, empirically, AGN light curves are seen to undergo dramatic short timescale variability that presumably corresponds to the creation of a single new active region within the distributed X-ray source. The iron-line response to these individual events can be described using linear transfer theory. We consider the line response to the activation/flaring of a new X-ray emitting region. Most of our detailed calculations are performed for the case of an X-ray source on the symmetry axis and at some height above the disk plane around a Kerr black hole. We also present preliminary calculations for off-axis flares. We suggest ways in which future, high-throughput X-ray observatories such as XMM and the Constellation X-ray Mission may use these reverberation signatures to probe both the mass and spin of AGN black holes as well as the X-ray source geometry. | [] | 4 | https://arxiv.org/pdf/astro-ph/9806327.pdf |
1993PhRvL..71.2851A | Collision of two black holes | 1993-01-01 | 9 | 0.46 | 178 | ['-', '-', '-', '-', '-', '-', 'black hole physics', '-'] | [] | We study the head-on collision of two equal-mass, nonrotating black holes. We consider various cases, from holes surrounded by a common horizon to holes separated by about 20M, where M is the mass of each hole. The wave forms and energy output are computed, showing that normal modes of the final black hole are clearly excited. We also estimate analytically the total gravitational radiation emitted, considering tidal heating of horizons and other effects. The analytic calculations, perturbation theory, and strong-field, nonlinear numerical calculations agree very well with each other. | [] | 5 | https://arxiv.org/pdf/gr-qc/9309016.pdf |
2001PhRvD..64f4011B | Supersymmetric conical defects: Towards a string theoretic description of black hole formation | 2001-01-01 | 9 | 0.45 | 178 | ['-', '-', '-', '-', '-', '-', '-', '-'] | [] | Conical defects, or point particles, in AdS<SUB>3</SUB> are one of the simplest nontrivial gravitating systems, and are particularly interesting because black holes can form from their collision. We embed the BPS conical defects of three dimensions into the N=4b supergravity in six dimensions, which arises from the IIB string theory compactified on K3. The required Kaluza-Klein reduction of the six dimensional theory on a sphere is analyzed in detail, including the relation to the Chern-Simons supergravities in three dimensions. We show that the six dimensional spaces obtained by embedding the 3D conical defects arise in the near-horizon limit of rotating black strings. Various properties of these solutions are analyzed and we propose a representation of our defects in the CFT dual to asymptotically AdS<SUB>3</SUB>×S<SUP>3</SUP> spaces. Our work is intended as a first step towards analyzing colliding defects that form black holes. | [] | 4 | https://arxiv.org/pdf/hep-th/0011217.pdf |
2009ApJ...704L..40B | Predicting the Direction of the Final Spin from the Coalescence of Two Black Holes | 2009-01-01 | 21 | 0.48 | 178 | ['black hole physics', 'galaxies nuclei', 'gravitational waves', 'relativity', '-', '-', '-'] | [] | Knowledge of the spin of the black hole resulting from the merger of a generic black-hole binary is of great importance for studying the cosmological evolution of supermassive black holes. Several attempts have been made to model the spin via simple expressions exploiting the results of numerical-relativity simulations. While these expressions are in reasonable agreement with the simulations, they neglect the precession of the binary's orbital plane, and cannot therefore be applied directly—i.e., without evolving the system to small separations using post-Newtonian theory—to binaries with separations larger than a few hundred gravitational radii. While not a problem in principle, this may be impractical if the formulas are employed in cosmological merger trees or N-body simulations, which provide the spins and angular momentum of the two black holes when their separation is of hundreds or thousands of gravitational radii. The formula that we propose is instead built on improved assumptions and gives, for any separation, a very accurate prediction both for the norm of the final spin and for its direction. By comparing with the numerical data, we also show that the final-spin direction is very accurately aligned with the binary's total angular momentum at large separation. Hence, observations of the final-spin direction (e.g., via a jet) can provide information on the binary's orbital plane at large separations and could be relevant, for instance, for studying X-shaped radio sources. | [] | 2 | https://arxiv.org/pdf/0904.2577.pdf |
2002PhLB..525..135R | Collider versus cosmic ray sensitivity to black hole production | 2002-01-01 | 5 | 0.46 | 178 | ['-', 'astrophysics', '-', '-', '-'] | [] | In scenarios with extra dimensions and TeV-scale quantum gravity, black holes are expected to be produced copiously at center-of-mass energies above the fundamental Planck scale. The Large Hadron Collider (LHC) may thus turn into a factory of black holes, at which their production and evaporation may be studied in detail. But even before the LHC starts operating, the Pierre Auger Observatory for cosmic rays, presently under construction, has an opportunity to search for black hole signatures. Black hole production in the scattering of ultrahigh energy cosmic neutrinos on nucleons in the atmosphere may initiate quasi-horizontal air showers with distinct characteristics above the Standard Model rate. In this Letter, we compare the sensitivity of LHC and Auger to black hole production by studying their respective reach in black hole production parameter space. Moreover, we present constraints in this parameter space from the non-observation of horizontal showers by the Fly's Eye Collaboration. We find that if the ultrahigh energy neutrino flux is at the level expected from cosmic ray interactions with the cosmic microwave background radiation, Auger has only a small window of opportunity to detect black holes before the start of the LHC. If, on the other hand, larger ultrahigh energy neutrino fluxes on the level of the upper limit from ``hidden'' hadronic astrophysical sources are realized in nature, then the first signs of black hole production may be observed at Auger. Moreover, in this case, the Fly's Eye constraints, although more model-dependent, turn out to be competitive with other currently available constraints on TeV-scale gravity which are mainly based on interactions associated with Kaluza-Klein gravitons. | [] | 2 | https://arxiv.org/pdf/hep-ph/0111042.pdf |
2022arXiv221105767E | Primordial Black Holes | 2022-01-01 | 102 | 0.53 | 178 | ['-', '-', '-', '-'] | [] | Aspects of primordial black holes, i.e. black holes formed in the early Universe, are reviewed. Special emphasis is put on their formation, their r{ô}le as dark matter candidates and their manifold signatures, particularly through gravitational waves. | [] | 3 | https://arxiv.org/pdf/2211.05767.pdf |
2017MNRAS.471.2801S | Hierarchical analysis of gravitational-wave measurements of binary black hole spin-orbit misalignments | 2017-01-01 | 36 | 0.48 | 178 | ['black hole physics', 'gravitational waves', 'methods data analysis', '-', '-', '-'] | [] | Binary black holes (BBHs) may form both through isolated binary evolution and through dynamical interactions in dense stellar environments. The formation channel leaves an imprint on the alignment between the BH spins and the orbital angular momentum. Gravitational waves (GW) from these systems directly encode information about the spin-orbit misalignment angles, allowing them to be (weakly) constrained. Identifying subpopulations of spinning BBHs will inform us about compact binary formation and evolution. We simulate a mixed population of BBHs with spin-orbit misalignments modelled under a range of assumptions. We then develop a hierarchical analysis and apply it to mock GW observations of these populations. Assuming a population with dimensionless spin magnitudes of χ = 0.7, we show that tens of observations will make it possible to distinguish the presence of subpopulations of coalescing binary black holes based on their spin orientations. With 100 observations, it will be possible to infer the relative fraction of coalescing BBHs with isotropic spin directions (corresponding to dynamical formation in our models) with a fractional uncertainty of ∼40 per cent. Meanwhile, only ∼5 observations are sufficient to distinguish between extreme models - all BBHs either having exactly aligned spins or isotropic spin directions. | [] | 3 | https://arxiv.org/pdf/1703.06873.pdf |
2013Ap&SS.344..429A | Shadow of Kerr-Taub-NUT black hole | 2013-01-01 | 29 | 0.46 | 178 | ['photons', '-', '-', '-', '-'] | [] | The shadow of a rotating black hole with nonvanishing gravitomagnetic charge has been studied. It was shown that in addition to the angular momentum of black hole the gravitomagnetic charge term deforms the shape of the black hole shadow. From the numerical results we have obtained that for a given value of the rotation parameter, the presence of a gravitomagnetic charge enlarges the shadow and reduces its deformation with respect to the spacetime without gravitomagnetic charge. Finally we have studied the capture cross section for massive particles by black hole with the nonvanishing gravitomagnetic charge. | [] | 5 | https://arxiv.org/pdf/1212.4949.pdf |
2019MNRAS.484.1031P | The fast, luminous ultraviolet transient AT2018cow: extreme supernova, or disruption of a star by an intermediate-mass black hole? | 2019-01-01 | 83 | 0.58 | 178 | ['-', '-', 'stars novae;cataclysmic variables', '-', '-'] | [] | Wide-field optical surveys have begun to uncover large samples of fast (t<SUB>rise</SUB> ≲ 5 d), luminous (M<SUB>peak</SUB> < -18), blue transients. While commonly attributed to the breakout of a supernova shock into a dense wind, the great distances to the transients of this class found so far have hampered detailed investigation of their properties. We present photometry and spectroscopy from a comprehensive worldwide campaign to observe AT 2018cow (ATLAS 18qqn), the first fast-luminous optical transient to be found in real time at low redshift. Our first spectra (<2 days after discovery) are entirely featureless. A very broad absorption feature suggestive of near-relativistic velocities develops between 3 and 8 days, then disappears. Broad emission features of H and He develop after >10 days. The spectrum remains extremely hot throughout its evolution, and the photospheric radius contracts with time (receding below R < 10<SUP>14</SUP> cm after 1 month). This behaviour does not match that of any known supernova, although a relativistic jet within a fallback supernova could explain some of the observed features. Alternatively, the transient could originate from the disruption of a star by an intermediate-mass black hole, although this would require long-lasting emission of highly super-Eddington thermal radiation. In either case, AT 2018cow suggests that the population of fast luminous transients represents a new class of astrophysical event. Intensive follow-up of this event in its late phases, and of any future events found at comparable distance, will be essential to better constrain their origins. | [] | 65 | https://arxiv.org/pdf/1808.00969.pdf |
2017MNRAS.464.3131K | Massive black hole binary mergers in dynamical galactic environments | 2017-01-01 | 46 | 0.55 | 178 | ['gravitational waves', 'galaxies evolution', 'galaxies kinematics and dynamics', 'galaxies nuclei', 'galaxies quasars', '-', '-'] | [] | Gravitational waves (GWs) have now been detected from stellar-mass black hole binaries, and the first observations of GWs from massive black hole (MBH) binaries are expected within the next decade. Pulsar timing arrays (PTA), which can measure the years long periods of GWs from MBH binaries (MBHBs), have excluded many standard predictions for the amplitude of a stochastic GW background (GWB). We use coevolved populations of MBHs and galaxies from hydrodynamic, cosmological simulations (`Illustris') to calculate a predicted GWB. The most advanced predictions so far have included binary hardening mechanisms from individual environmental processes. We present the first calculation including all of the environmental mechanisms expected to be involved: dynamical friction, stellar `loss-cone' scattering, and viscous drag from a circumbinary disc. We find that MBH binary lifetimes are generally multiple gigayears, and only a fraction coalesce by redshift zero. For a variety of parameters, we find all GWB amplitudes to be below the most stringent PTA upper limit of A_{yr^{-1}} ≈ 10^{-15}. Our fairly conservative fiducial model predicts an amplitude of A_{yr^{-1}} ≈ 0.4× 10^{-15}. At lower frequencies, we find A_{0.1 yr^{-1}} ≈ 1.5× 10^{-15} with spectral indices between -0.4 and -0.6 - significantly flatter than the canonical value of -2/3 due to purely GW-driven evolution. Typical MBHBs driving the GWB signal come from redshifts around 0.3, with total masses of a few times 10<SUP>9</SUP> M<SUB>⊙</SUB>, and in host galaxies with very large stellar masses. Even without GWB detections, our results can be connected to observations of dual active galactic nuclei to constrain binary evolution. | [] | 3 | https://arxiv.org/pdf/1606.01900.pdf |
2019PhRvL.123g1103W | Repulsive Interactions and Universal Properties of Charged Anti-de Sitter Black Hole Microstructures | 2019-01-01 | 25 | 0.46 | 177 | ['-', '-'] | [] | The Ruppeiner geometry of thermodynamic fluctuations provides a powerful diagnostic of black hole microstructures. We investigate this for charged anti-de Sitter black holes and find that, while an attractive microstructure interaction dominates for most parameter ranges, a weak repulsive interaction dominates for small black holes of high temperature. This unique property distinguishes the black hole system from that of a van der Waals fluid, where only attractive microstructure interactions are found. We also find two other novel universal properties for charged black holes. One is that the repulsive interaction is independent of the black hole charge and temperature. The other is that the behavior of the Ruppeiner curvature scalar near criticality is characterized by a dimensionless constant that is identical to that for a van der Waals fluid, providing us with new insight into black hole microstructures. | [] | 3 | https://arxiv.org/pdf/1906.10840.pdf |
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