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1
Nomoto, K., K. Maeda, H. Umeda e N. Tominaga. "Nucleosynthesis in Population III Supernovae". Highlights of Astronomy 13 (2005): 560–65. http://dx.doi.org/10.1017/s1539299600016580.
Testo completoAbstract (sommario):
AbstractStars more massive than ~ 20–25 M⊙ form a black hole at the end of their evolution. Stars with non-rotating black holes are likely to collapse ”quietly” ejecting a small amount of heavy elements (Faint supernovae). In contrast, stars with rotating black holes are likely to give rise to very energetic supernovae (Hypernovae). Nucleosynthesis in Hypernovae is characterized by larger abundance ratios (Zn,Co,V,Ti)/Fe and smaller (Mn,Cr)/Fe than normal supernovae, which can explain the observed trend of these ratios in extremely metal-poor stars. Nucleosynthesis in Faint supernovae is characterized by a large amount of fall-back. We show that the abundance pattern of the recently discovered most Fe-poor star, HE0107-5240, and other extremely metal-poor carbon-rich stars are in good accord with those of black-hole-forming supernovae, but not pair-instability supernovae. This suggests that black-hole-forming supernovae made important contributions to the early Galactic (and cosmic) chemical evolution as the First (Pop III) Supernovae.
2
Stevenson, Simon. "Biases in Estimates of Black Hole Kicks from the Spin Distribution of Binary Black Holes". Astrophysical Journal Letters 926, n. 2 (1 febbraio 2022): L32. http://dx.doi.org/10.3847/2041-8213/ac5252.
Testo completoAbstract (sommario):
Abstract A population of more than 50 binary black hole mergers has now been observed by the LIGO and Virgo gravitational-wave observatories. While neutron stars are known to have large velocities associated with impulsive kicks imparted to them at birth in supernovae, whether black holes receive similar kicks, and of what magnitude, remains an open question. Recently, Callister et al. analyzed the binary black hole population under the hypothesis that they were all formed through isolated binary evolution and claimed that large black hole kicks (greater than 260 km s−1 at 99% confidence) were required for the spin distribution of merging binary black holes to match observations. Here we highlight that a key assumption made by Callister et al.—that all secondary black holes can be tidally spun up—is not motivated by physical models and may lead to a bias in their estimate of the magnitudes of black hole kicks. We make only minor changes to the Callister et al. model, accounting for a population of wider merging binaries where tidal synchronization is ineffective. We show that this naturally produces a bimodal spin distribution for secondary black holes and that the spin–orbit misalignments observed in the binary black hole population can be explained by more typical black hole kicks of order 100 km s−1, consistent with kicks inferred from Galactic X-ray binaries containing black holes. We conclude that the majority of the binary black hole population is consistent with forming through isolated binary evolution.
3
Pesce, Dominic W., Daniel C. M. Palumbo, Angelo Ricarte, Avery E. Broderick, Michael D. Johnson, Neil M. Nagar, Priyamvada Natarajan e José L. Gómez. "Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT". Galaxies 10, n. 6 (2 dicembre 2022): 109. http://dx.doi.org/10.3390/galaxies10060109.
Testo completoAbstract (sommario):
We present estimates for the number of supermassive black holes (SMBHs) for which the next-generation Event Horizon Telescope (ngEHT) can identify the black hole “shadow”, along with estimates for how many black hole masses and spins the ngEHT can expect to constrain using measurements of horizon-resolved emission structure. Building on prior theoretical studies of SMBH accretion flows and analyses carried out by the Event Horizon Telescope (EHT) collaboration, we construct a simple geometric model for the polarized emission structure around a black hole, and we associate parameters of this model with the three physical quantities of interest. We generate a large number of realistic synthetic ngEHT datasets across different assumed source sizes and flux densities, and we estimate the precision with which our defined proxies for physical parameters could be measured from these datasets. Under April weather conditions and using an observing frequency of 230 GHz, we predict that a “Phase 1” ngEHT can potentially measure ∼50 black hole masses, ∼30 black hole spins, and ∼7 black hole shadows across the entire sky.
4
Doctor, Zoheyr, Ben Farr e Daniel E. Holz. "Black Hole Leftovers: The Remnant Population from Binary Black Hole Mergers". Astrophysical Journal Letters 914, n. 1 (1 giugno 2021): L18. http://dx.doi.org/10.3847/2041-8213/ac0334.
Testo completo
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Callister, Thomas A., Simona J. Miller, Katerina Chatziioannou e Will M. Farr. "No Evidence that the Majority of Black Holes in Binaries Have Zero Spin". Astrophysical Journal Letters 937, n. 1 (1 settembre 2022): L13. http://dx.doi.org/10.3847/2041-8213/ac847e.
Testo completoAbstract (sommario):
Abstract The spin properties of merging black holes observed with gravitational waves can offer novel information about the origin of these systems. The magnitudes and orientations of black hole spins offer a record of binaries’ evolutionary history, encoding information about massive stellar evolution and the astrophysical environments in which binary black holes are assembled. Recent analyses of the binary black hole population have yielded conflicting portraits of the black hole spin distribution. Some works suggest that black hole spins are small but nonzero and exhibit a wide range of misalignment angles relative to binaries’ orbital angular momenta. Other works conclude that the majority of black holes are nonspinning while the remainder are rapidly rotating and primarily aligned with their orbits. We revisit these conflicting conclusions, employing a variety of complementary methods to measure the distribution of spin magnitudes and orientations among binary black hole mergers. We find that the existence of a subpopulation of black holes with vanishing spins is not required by current data. Should such a subpopulation exist, we conclude that it must contain ≲60% of binaries. Additionally, we find evidence for significant spin–orbit misalignment among the binary black hole population, with some systems exhibiting misalignment angles greater than 90°, and see no evidence for an approximately spin-aligned subpopulation.
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Rees, Martin J., e Marta Volonteri. "Massive black holes: formation and evolution". Proceedings of the International Astronomical Union 2, S238 (agosto 2006): 51–58. http://dx.doi.org/10.1017/s1743921307004681.
Testo completoAbstract (sommario):
AbstractSupermassive black holes are nowadays believed to reside in most local galaxies. Observations have revealed us vast information on the population of local and distant black holes, but the detailed physical properties of these dark massive objects are still to be proven. Accretion of gas and black hole mergers play a fundamental role in determining the two parameters defining a black hole: mass and spin. We briefly review here the basic properties of the population of supermassive black holes, focusing on the still mysterious formation of the first massive black holes, and their evolution from early times to now.
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Reynolds, Christopher S. "Observational Constraints on Black Hole Spin". Annual Review of Astronomy and Astrophysics 59, n. 1 (8 settembre 2021): 117–54. http://dx.doi.org/10.1146/annurev-astro-112420-035022.
Testo completoAbstract (sommario):
The spin of a black hole is an important quantity to study, providing a window into the processes by which a black hole was born and grew. Furthermore, spin can be a potent energy source for powering relativistic jets and energetic particle acceleration. In this review, I describe the techniques currently used to detect and measure the spins of black holes. It is shown that: ▪ Two well-understood techniques, X-ray reflection spectroscopy and thermal continuum fitting, can be used to measure the spins of black holes that are accreting at moderate rates. There is a rich set of other electromagnetic techniques allowing us to extend spin measurements to lower accretion rates. ▪ Many accreting supermassive black holes are found to be rapidly spinning, although a population of more slowly spinning black holes emerges at masses above [Formula: see text] as expected from recent structure formation models. ▪ Many accreting stellar-mass black holes in X-ray binary systems are rapidly spinning and must have been born in this state. ▪ The advent of gravitational wave astronomy has enabled the detection of spin effects in merging binary black holes. Most of the premerger black holes are found to be slowly spinning, a notable exception being an object that may itself be a merger product. ▪ The stark difference in spins between the black hole X-ray binary and the binary black hole populations shows that there is a diversity of formation mechanisms. Given the array of new electromagnetic and gravitational wave capabilities currently being planned, the future of black hole spin studies is bright.
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Treister, Ezequiel, Claudia M. Urry, Kevin Schawinski, Brooke D. Simmons, Priyamvada Natarajan e Marta Volonteri. "The Multiwavelength AGN Population and the X-ray Background". Proceedings of the International Astronomical Union 9, S304 (ottobre 2013): 188–94. http://dx.doi.org/10.1017/s1743921314003731.
Testo completoAbstract (sommario):
AbstractIn order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (LX~ 1044 erg/s) sources (Seyfert-type AGN), at z~ 0.5−1 and in heavily obscured but Compton-thin, NH~ 1023cm−2, systems. However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We further investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~ 0 to z~ 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth. Finally, we constrain the total accreted mass density in supermassive black holes at z > 6, inferred via the upper limit derived from the integrated X-ray emission from a sample of photometrically selected galaxy candidates. We estimate an accreted mass density <1000 M⊙Mpc−3 at z~ 6, significantly lower than the previous predictions from some existing models of early black hole growth and earlier prior observations.
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Netzer, Hagai. "Black Hole Demographics: Statistical Characteristics of Accreting Black Holes". Proceedings of the International Astronomical Union 5, S267 (agosto 2009): 213–22. http://dx.doi.org/10.1017/s1743921310006319.
Testo completoAbstract (sommario):
This review summarizes the important properties of active black holes (BHs) up to z ~ 2; their mass, accretion rate, and growth rate. At higher redshifts, such information is only available for small samples that do not represent the entire population of active galactic nuclei (AGNs). Black hole spin is still unknown; it is speculated to change with redshift, but with little experimental evidence. The available data sets also enable a direct comparison of BH accretion rates and host galaxy star-formation rates (SFRs). The ratio of the BH growth rate g(BH) and the bulge growth rate g(bulge), suggests that the two are proportional to each other. The local value of g(bulge)/g(BH) in low-luminosity AGNs is of order 100 and the corresponding ratio in high-luminosity, high-redshift AGNs is of order 10. This has important implications regarding the parallel evolution of active BHs and their hosts.
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Zevin, Michael, e Daniel E. Holz. "Avoiding a Cluster Catastrophe: Retention Efficiency and the Binary Black Hole Mass Spectrum". Astrophysical Journal Letters 935, n. 1 (1 agosto 2022): L20. http://dx.doi.org/10.3847/2041-8213/ac853d.
Testo completoAbstract (sommario):
Abstract The population of binary black hole mergers identified through gravitational waves has uncovered unexpected features in the intrinsic properties of black holes in the universe. One particularly surprising and exciting result is the possible existence of black holes in the pair-instability mass gap, ∼50–120 M ⊙. Dense stellar environments can populate this region of mass space through hierarchical mergers, with the retention efficiency of black hole merger products strongly dependent on the escape velocity of the host environment. We use simple toy models to represent hierarchical merger scenarios in various dynamical environments. We find that hierarchical mergers in environments with high escape velocities (≳300 km s−1) are efficiently retained. If such environments dominate the binary black hole merger rate, this would lead to an abundance of high-mass mergers that is potentially incompatible with the empirical mass spectrum from the current catalog of binary black hole mergers. Models that efficiently generate hierarchical mergers, and contribute significantly to the observed population, must therefore be tuned to avoid a “cluster catastrophe” of overproducing binary black hole mergers within and above the pair-instability mass gap.
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Ricarte, Angelo, Fabio Pacucci, Nico Cappelluti e Priyamvada Natarajan. "The clustering of undetected high-redshift black holes and their signatures in cosmic backgrounds". Monthly Notices of the Royal Astronomical Society 489, n. 1 (23 agosto 2019): 1006–22. http://dx.doi.org/10.1093/mnras/stz1891.
Testo completoAbstract (sommario):
ABSTRACT There exist hitherto unexplained fluctuations in the cosmic infrared background on arcminute scales and larger. These have been shown to cross-correlate with the cosmic X-ray background, leading several authors to attribute the excess to a high-redshift growing black hole population. In order to investigate potential sources that could explain this excess, in this paper, we develop a new framework to compute the power spectrum of undetected sources that do not have constant flux as a function of halo mass. In this formulation, we combine a semi-analytic model for black hole growth and their simulated spectra from hydrodynamical simulations. Revisiting the possible contribution of a high-redshift black hole population, we find that too much black hole growth is required at early epochs for z > 6 accretion to explain these fluctuations. Examining a population of accreting black holes at more moderate redshifts, z ∼ 2–3, we find that such models produce a poor fit to the observed fluctuations while simultaneously overproducing the local black hole mass density. Additionally, we rule out the hypothesis of a missing Galactic foreground of warm dust that produces coherent fluctuations in the X-ray via reflection of Galactic X-ray binary emission. Although we firmly rule out accreting massive black holes as the source of these missing fluctuations, additional studies will be required to determine their origin.
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Payne, Ethan, Ling Sun, Kyle Kremer, Paul D. Lasky e Eric Thrane. "The Imprint of Superradiance on Hierarchical Black Hole Mergers". Astrophysical Journal 931, n. 2 (26 maggio 2022): 79. http://dx.doi.org/10.3847/1538-4357/ac66df.
Testo completoAbstract (sommario):
Abstract Ultralight bosons are a proposed solution to outstanding problems in cosmology and particle physics: they provide a dark-matter candidate while potentially explaining the strong charge-parity problem. If they exist, ultralight bosons can interact with black holes through the superradiant instability. In this work we explore the consequences of this instability on the evolution of hierarchical black holes within dense stellar clusters. By reducing the spin of individual black holes, superradiance reduces the recoil velocity of merging binary black holes, which, in turn, increases the retention fraction of hierarchical merger remnants. We show that the existence of ultralight bosons with mass 2 × 10−14 ≲ μ/eV ≲ 2 × 10−13 would lead to an increased rate of hierarchical black hole mergers in nuclear star clusters. An ultralight boson in this energy range would result in up to ≈60% more present-day nuclear star clusters supporting hierarchical growth. The presence of an ultralight boson can also double the rate of intermediate-mass black hole mergers to ≈0.08 Gpc−3 yr−1 in the local universe. These results imply that a select range of ultralight boson masses can have far-reaching consequences for the population of black holes in dense stellar environments. Future studies into black hole cluster populations and the spin distribution of hierarchically formed black holes will test this scenario.
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Broekgaarden, Floor S., Simon Stevenson e Eric Thrane. "Signatures of Mass Ratio Reversal in Gravitational Waves from Merging Binary Black Holes". Astrophysical Journal 938, n. 1 (1 ottobre 2022): 45. http://dx.doi.org/10.3847/1538-4357/ac8879.
Testo completoAbstract (sommario):
Abstract The spins of merging binary black holes offer insights into their formation history. Recently it has been argued that in the isolated binary evolution of two massive stars the firstborn black hole is slowly rotating, while the progenitor of the second-born black hole can be tidally spun up if the binary is tight enough. Naively, one might therefore expect that only the less massive black hole in merging binaries exhibits nonnegligible spin. However, if the mass ratio of the binary is “reversed” (typically during the first mass transfer episode), it is possible for the tidally spun up second-born to become the more massive black hole. We study the properties of such mass ratio reversed binary black hole mergers using a large set of 560 population synthesis models. We find that the more massive black hole is formed second in ≳70% of binary black holes observable by LIGO, Virgo, and KAGRA for most model variations we consider, with typical total masses ≳20 M ⊙ and mass ratios q = m 2/m 1 ∼ 0.7 (where m 1 > m 2). The formation history of these systems typically involves only stable mass transfer episodes. The second-born black hole has nonnegligible spin (χ > 0.05) in up to 25% of binary black holes, with among those the more (less) massive black hole is spinning in 0%–80% (20%–100%) of the cases, varying greatly in our models. We discuss our models in the context of several observed gravitational-wave events and the observed mass ratio—effective spin correlation.
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Hong, Jongsuk, Abbas Askar, Mirek Giersz, Arkadiusz Hypki e Suk-Jin Yoon. "mocca-survey Database I: Binary black hole mergers from globular clusters with intermediate mass black holes". Monthly Notices of the Royal Astronomical Society 498, n. 3 (4 settembre 2020): 4287–94. http://dx.doi.org/10.1093/mnras/staa2677.
Testo completoAbstract (sommario):
ABSTRACT The dynamical formation of black hole binaries in globular clusters that merge due to gravitational waves occurs more frequently in higher stellar density. Meanwhile, the probability to form intermediate mass black holes (IMBHs) also increases with the density. To explore the impact of the formation and growth of IMBHs on the population of stellar mass black hole binaries from globular clusters, we analyse the existing large survey of Monte Carlo globular cluster simulation data (mocca-survey Database I). We show that the number of binary black hole mergers agrees with the prediction based on clusters’ initial properties when the IMBH mass is not massive enough or the IMBH seed forms at a later time. However, binary black hole formation and subsequent merger events are significantly reduced compared to the prediction when the present-day IMBH mass is more massive than ${\sim}10^4\, \rm M_{\odot }$ or the present-day IMBH mass exceeds about 1 per cent of cluster’s initial total mass. By examining the maximum black hole mass in the system at the moment of black hole binary escaping, we find that ∼90 per cent of the merging binary black holes escape before the formation and growth of the IMBH. Furthermore, large fraction of stellar mass black holes are merged into the IMBH or escape as single black holes from globular clusters in cases of massive IMBHs, which can lead to the significant underpopulation of binary black holes merging with gravitational waves by a factor of 2 depending on the clusters’ initial distributions.
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Fryer, C. L. "Population Synthesis of GRB Progenitors: Problems With Kicks". Symposium - International Astronomical Union 195 (2000): 339–46. http://dx.doi.org/10.1017/s0074180900163119.
Testo completoAbstract (sommario):
Accretion disks around stellar-mass black holes are now thought to be the engines which power classical gamma-ray bursts (GRBs). These disks are formed almost exclusively in binaries, and to study the characteristics of the progenitors of these black-hole accretion disk (BHAD) GRBs, we must understand the uncertainties in binary population synthesis calculations. Kicks imparted onto nascent neutron stars and black holes are among the most misunderstood concepts of binary population synthesis. In this paper, we outline the current understanding (or lack of understanding) of these kicks and discuss their effect on BHAD GRBs and binary population synthesis as a whole.
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Thomas, Nicole, Romeel Davé, Matt J. Jarvis e Daniel Anglés-Alcázar. "The radio galaxy population in the simba simulations". Monthly Notices of the Royal Astronomical Society 503, n. 3 (9 marzo 2021): 3492–509. http://dx.doi.org/10.1093/mnras/stab654.
Testo completoAbstract (sommario):
ABSTRACT We examine the 1.4 GHz radio luminosities of galaxies arising from star formation and active galactic nuclei (AGNs) within the state-of-the-art cosmological hydrodynamic simulation Simba. Simba grows black holes via gravitational torque limited accretion from cold gas and Bondi accretion from hot gas, and employs AGN feedback including jets at low Eddington ratios. We define a population of radio loud AGNs (RLAGNs) based on the presence of ongoing jet feedback. Within RLAGN, we define high and low excitation radio galaxies (HERGs and LERGs) based on their dominant mode of black hole accretion: torque limited accretion representing feeding from a cold disc, or Bondi representing advection-dominated accretion from a hot medium. Simba predicts good agreement with the observed radio luminosity function (RLF) and its evolution, overall as well as separately for HERGs and LERGs. Quiescent galaxies with AGN-dominated radio flux dominate the RLF at $\gtrsim 10^{22-23}$ W Hz−1, while star formation dominates at lower radio powers. Overall, RLAGNs have higher black hole accretion rates and lower star formation rates than non-RLAGN at a given stellar mass or velocity dispersion, but have similar black hole masses. Simba predicts an LERG number density of 8.53 Mpc−3, ∼10× higher than for HERGs, broadly as observed. While LERGs dominate among most massive galaxies with the largest black holes and HERGs dominate at high specific star formation rates, they otherwise largely populate similar-sized dark matter haloes and have similar host galaxy properties. Simba thus predicts that deeper radio surveys will reveal an increasing overlap between the host galaxy demographics of HERGs and LERGs.
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Mezcua, Mar. "Feeding and feedback from little monsters: AGN in dwarf galaxies". Proceedings of the International Astronomical Union 15, S359 (marzo 2020): 238–42. http://dx.doi.org/10.1017/s1743921320002240.
Testo completoAbstract (sommario):
AbstractDetecting the seed black holes from which quasars formed is extremely challenging; however, those seeds that did not grow into supermassive should be found as intermediate-mass black holes (IMBHs) of 100 – 105 M⊙ in local dwarf galaxies. The use of deep multiwavelength surveys has revealed that a population of actively accreting IMBHs (low-mass AGN) exists in dwarf galaxies at least out to z ˜3. The black hole occupation fraction of these galaxies suggests that the early Universe seed black holes formed from direct collapse of gas, which is reinforced by the possible flattening of the black hole-galaxy scaling relations at the low-mass end. This scenario is however challenged by the finding that AGN feedback can have a strong impact on dwarf galaxies, which implies that low-mass AGN in dwarf galaxies might not be the untouched relics of the early seed black holes. This has important implications for seed black hole formation models.
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Zhou, Shuying, Mouyuan Sun, Tong Liu, Jian-Min Wang, Jun-Xian Wang e Yongquan Xue. "Stellar Black Holes Can “Stretch” Supermassive Black Hole Accretion Disks". Astrophysical Journal Letters 966, n. 1 (24 aprile 2024): L9. http://dx.doi.org/10.3847/2041-8213/ad3c3f.
Testo completoAbstract (sommario):
Abstract Stellar black holes (sBHs) are widely believed to exist in the accretion disks of active galactic nuclei (AGNs). Previous studies often focus on the transient emission produced by embedded sBHs. Here, we explore the possible observational consequences of an AGN accretion disk that contains a population of accreting sBHs. Embedded accreting sBHs change the effective temperature distribution of the AGN accretion disk by heating gas in the outer regions. Two possible observational consequences are presented. First, the spectral energy distribution has a turnover feature at ∼4700 Å when the supermassive black hole mass is ∼108 M ⊙, which can help explain the observed shallow spectral shape at wavelengths >5000 Å for the Sloan Digital Sky Survey quasar composite spectrum. Second, the half-light radius of a given relatively long wavelength is significantly larger than for an AGN disk without sBHs, which can be tested by microlensing observations. With appropriate sBH distributions, the model can be reconciled with quasar microlensing disk sizes. We propose that the half-light radius–wavelength relation can be utilized to investigate the distributions of embedded sBHs in AGN accretion disks.
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Mukherjee, Suvodip, e Joseph Silk. "Can we distinguish astrophysical from primordial black holes via the stochastic gravitational wave background?" Monthly Notices of the Royal Astronomical Society 506, n. 3 (8 luglio 2021): 3977–85. http://dx.doi.org/10.1093/mnras/stab1932.
Testo completoAbstract (sommario):
ABSTRACT One of the crucial windows for distinguishing astrophysical black holes from primordial black holes is through the redshift evolution of their respective merger rates. The low redshift population of black holes of astrophysical origin is expected to follow the star formation rate. The corresponding peak in their merger rate peaks at a redshift smaller than that of the star formation rate peak (zp ≈ 2), depending on the time delay between the formation and mergers of black holes. Black holes of primordial origin are going to be present before the formation of the stars, and the merger rate of these sources at high redshift is going to be large. We propose a joint estimation of a hybrid merger rate from the stochastic gravitational wave background, which can use the cosmic history of merger rates to distinguish between the two populations of black holes. Using the latest bounds on the amplitude of the stochastic gravitational wave background amplitude from the third observation run of LIGO/Virgo, we obtain weak constraints at $68{{\ \rm per\ cent}}$ C.L. on the primordial black hole merger rate index $2.56_{-1.76}^{+1.64}$ and astrophysical black hole time delay $6.7_{-4.74}^{+4.22}$ Gyr. We should be able to distinguish between the different populations of black holes with the forthcoming O5 and A+ detector sensitivities.
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Häberle, Maximilian, Nadine Neumayer, Anil Seth, Andrea Bellini, Mattia Libralato, Holger Baumgardt, Matthew Whitaker et al. "Fast-moving stars around an intermediate-mass black hole in ω Centauri". Nature 631, n. 8020 (10 luglio 2024): 285–88. http://dx.doi.org/10.1038/s41586-024-07511-z.
Testo completoAbstract (sommario):
AbstractBlack holes have been found over a wide range of masses, from stellar remnants with masses of 5–150 solar masses (M☉), to those found at the centres of galaxies with M > 105M☉. However, only a few debated candidate black holes exist between 150M☉ and 105M☉. Determining the population of these intermediate-mass black holes is an important step towards understanding supermassive black hole formation in the early universe1,2. Several studies have claimed the detection of a central black hole in ω Centauri, the most massive globular cluster of the Milky Way3–5. However, these studies have been questioned because of the possible mass contribution of stellar mass black holes, their sensitivity to the cluster centre and the lack of fast-moving stars above the escape velocity6–9. Here we report the observations of seven fast-moving stars in the central 3 arcsec (0.08 pc) of ω Centauri. The velocities of the fast-moving stars are significantly higher than the expected central escape velocity of the star cluster, so their presence can be explained only by being bound to a massive black hole. From the velocities alone, we can infer a firm lower limit of the black hole mass of about 8,200M☉, making this a good case for an intermediate-mass black hole in the local universe.
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Ellis, Sebastian A. R. "Premature black hole death of Population III stars by dark matter". Journal of Cosmology and Astroparticle Physics 2022, n. 05 (1 maggio 2022): 025. http://dx.doi.org/10.1088/1475-7516/2022/05/025.
Testo completoAbstract (sommario):
Abstract Population III stars were the first generation of stars, formed in minihalos of roughly primordial element abundances, and therefore metal-free. They are thought to have formed at the cores of dense dark matter clouds. Interactions between baryons and dark matter can therefore have had an important impact on their evolution. In this paper we consider the capture of non- or weakly-annihilating dark matter by these early massive stars. In a wide region of parameter space, interactions of dark matter with baryons lead to premature death of the star as a black hole. We sketch how this modification of the standard evolutionary history of Population III stars might impact the epoch of reionisation, by modifying the amount of UV emission, the transition to Population II star formation, and the X-ray and radio emission from accretion onto the black hole remnants. Signals of massive black holes originating from Population III stars could be observed through gravitational waves from their mergers. Finally, the observation of pair-instability supernovae could effectively preclude premature black hole death across a wide range of parameter space, ranging in mass from m DM ∼ 0.1 GeV to m DM ∼ m Pl.
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Fusco, Michael S., Benjamin L. Davis, Julia Kennefick, Daniel Kennefick e Marc S. Seigar. "Probing the Low-Mass End of the Black Hole Mass Function via a Study of Faint Local Spiral Galaxies". Universe 8, n. 12 (6 dicembre 2022): 649. http://dx.doi.org/10.3390/universe8120649.
Testo completoAbstract (sommario):
We present an analysis of the pitch angle distribution function (PADF) for nearby galaxies and its resulting black hole mass function (BHMF) via the well-known relationship between pitch angle and black hole mass. Our sample consists of a subset of 74 spiral galaxies from the Carnegie-Irvine Galaxy Survey with absolute B-band magnitude MB>−19.12 mag and luminosity distance DL≤25.4 Mpc, which is an extension of a complementary set of 140 more luminous (MB≤−19.12 mag) late-type galaxies. We find the PADFs of the two samples are, somewhat surprisingly, not strongly dissimilar; a result that may hold important implications for spiral formation theories. Our data show a distinct bimodal population manifest in the pitch angles of the Sa–Sc types and separately the Scd–Sm types, with Sa–Sc types having tighter spiral arms on average. Importantly, we uncover a distinct bifurcation of the BHMF, such that the Sa–Sc galaxies typically host so-called “supermassive” black holes (M•≳106M⊙), whereas Scd–Sm galaxies accordingly harbor black holes that are “less-than-supermassive” (M•≲106M⊙). It is amongst this latter population of galaxies where we expect fruitful bounties of elusive intermediate-mass black holes (IMBHs), through which a better understanding will help form more precise benchmarks for future generations of gravitational wave detectors.
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Casares, Jorge. "Observational evidence for stellar-mass black holes". Proceedings of the International Astronomical Union 2, S238 (agosto 2006): 3–12. http://dx.doi.org/10.1017/s1743921307004590.
Testo completoAbstract (sommario):
AbstractRadial velocity studies of X-ray binaries provide the most solid evidence for the existence of stellar-mass black holes. We currently have 20 confirmed cases, with dynamical masses in excess of 3 M⊙. Accurate masses have been obtained for a subset of systems which gives us a hint at the mass spectrum of the black hole population. This review summarizes the history of black hole discoveries and presents the latest results in the field.
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Kauffmann, Guinevere, e Timothy M. Heckman. "The formation of bulges and black holes: lessons from a census of active galaxies in the SDSS". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, n. 1828 (12 gennaio 2005): 621–43. http://dx.doi.org/10.1098/rsta.2004.1516.
Testo completoAbstract (sommario):
We examine the relationship between galaxies, supermassive black holes and AGN using a sample of 23 000 narrow–emission–line (‘type 2’) active galactic nuclei (AGN) drawn from a sample of 123 000 galaxies from the Sloan Digital Sky Survey. We have studied how AGN host properties compare with those of normal galaxies and how they depend on the luminosity of the active nucleus. We find that AGN reside in massive galaxies and have distributions of sizes and concentrations that are similar to those of the early–type galaxies in our sample. The host galaxies of low–luminosity AGN have stellar populations similar to normal early types. The hosts of highluminosity AGN have much younger mean stellar ages, and a significant fraction have experienced recent starbursts. High–luminosity AGN are also found in lower–density environments. We then use the stellar velocity dispersions of the AGN hosts to estimate black hole masses and their [OIII]λ5007 emission–line luminosities to estimate black hole accretion rates.We find that the volume averaged ratio of star formation to black hole accretion is ∼1000 for the bulge–dominated galaxies in our sample. This is remarkably similar to the observed ratio of stellar mass to black hole mass in nearby bulges. Most of the present–day black hole growth is occurring in black holes with masses less than 3 × 10 7 M ⊙. Our estimated accretion rates imply that low–mass black holes are growing on a time–scale that is comparable with the age of the Universe. Around 50% this growth takes place in AGN that are radiating within a factor of five of the Eddington luminosity. Such systems are rare, making up only 0.2% of the lowmass black hole population at the present day. The remaining growth occurs in lower luminosity AGN. The growth time–scale increases by more than an order of magnitude for the most massive black holes in our sample. We conclude that the evolution of the AGN luminosity function documented in recent optical and X–ray surveys is driven by a decrease in the characteristic mass scale of actively accreting black holes.
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Edelman, Bruce, Zoheyr Doctor e Ben Farr. "Poking Holes: Looking for Gaps in LIGO/Virgo’s Black Hole Population". Astrophysical Journal Letters 913, n. 2 (28 maggio 2021): L23. http://dx.doi.org/10.3847/2041-8213/abfdb3.
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Gallegos-Garcia, Monica, Christopher P. L. Berry, Pablo Marchant e Vicky Kalogera. "Binary Black Hole Formation with Detailed Modeling: Stable Mass Transfer Leads to Lower Merger Rates". Astrophysical Journal 922, n. 2 (24 novembre 2021): 110. http://dx.doi.org/10.3847/1538-4357/ac2610.
Testo completoAbstract (sommario):
Abstract Rapid binary population synthesis codes are often used to investigate the evolution of compact-object binaries. They typically rely on analytical fits of single-star evolutionary tracks and parameterized models for interactive phases of evolution (e.g., mass transfer on a thermal timescale, determination of dynamical instability, and common envelope) that are crucial to predict the fate of binaries. These processes can be more carefully implemented in stellar structure and evolution codes such as MESA. To assess the impact of such improvements, we compare binary black hole mergers as predicted in models with the rapid binary population synthesis code COSMIC to models ran with MESA simulations through mass transfer and common-envelope treatment. We find that results significantly differ in terms of formation paths, the orbital periods and mass ratios of merging binary black holes, and consequently merger rates. While common-envelope evolution is the dominant formation channel in COSMIC, stable mass transfer dominates in our MESA models. Depending upon the black hole donor mass, and mass-transfer and common-envelope physics, at subsolar metallicity, COSMIC overproduces the number of binary black hole mergers by factors of 2–35 with a significant fraction of them having merger times orders of magnitude shorter than the binary black holes formed when using detailed MESA models. Therefore we find that some binary black hole merger rate predictions from rapid population syntheses of isolated binaries may be overestimated by factors of ∼ 5–500. We conclude that the interpretation of gravitational-wave observations requires the use of detailed treatment of these interactive binary phases.
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Nitta, S. "Statistical Properties of Kerr BH Flywheel Model of QSOs/AGNs". Symposium - International Astronomical Union 195 (2000): 417–18. http://dx.doi.org/10.1017/s0074180900163351.
Testo completoAbstract (sommario):
The aim of this work is to demonstrate the properties of the magnetospheric model around Kerr black holes, so-called the “flywheel” (rotation powered) model. The fly-wheel engine of the BH accretion disk system is applied to the statistics of QSOs/AGNs. Nitta, Takahashi, & Tomimatsu clarified the individual evolution of the Kerr black-hole fly-wheel engine, which is parameterized by black-hole mass, initial Kerr parameter, magnetic field near the horizon, and a dimensionless small parameter. We impose a statistical model for the initial mass function of an ensemble of black holes using the Press-Schechter formalism. With the help of additional assumptions, we can discuss the evolution of the luminosity function and the spatial number density (population) of QSOs/AGNs. The result explains well the decrease of very bright QSOs and decrease of population after z ~ 2.
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Sadler, Elaine M., Scott M. Croom, John H. Y. Ching, Helen M. Johnston, Russell D. Cannon e Tom Mauch. "Radio-Mode Feedback in Massive Galaxies at Redshift 0 < z < 1". Proceedings of the International Astronomical Union 5, S267 (agosto 2009): 377–82. http://dx.doi.org/10.1017/s1743921310006745.
Testo completoAbstract (sommario):
AbstractWe have carried out a large observational study of the radio luminosities, stellar populations, and environments of massive galaxies over the redshift range 0 < z < 1. Radio jets powered by an accreting central black hole are common in massive galaxies, and there is a large class of “optically quiet AGN,” with radio emission but no optical/IR signature of black-hole accretion. The central black holes in these galaxies are probably accreting in a radiatively inefficient mode, and our results suggest that “radio-mode feedback” as described by Croton et al. is likely to occur in all masssive early-type galaxies at z < 0.8. While it appears that radio-loud AGN occur episodically in all massive early-type galaxies, we also identify a sub-population of galaxies with powerful radio sources and a prominent younger (~ 108 yr) stellar population that may have undergone recent mergers.
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Shojaie, H., e M. Farhoudi. "Black holes in the varying speed of light theory". Canadian Journal of Physics 85, n. 12 (1 dicembre 2007): 1409–15. http://dx.doi.org/10.1139/p07-131.
Testo completoAbstract (sommario):
We consider the effect of the varying speed of light theory on nonrotating black holes. We show that in any varying-c theory, the Schwarzschild solution is neither static nor stationary. For a no-charged black hole, the singularity in the Schwarzschild horizon cannot be removed by coordinate transformation. Hence, no matter can enter the horizon, and the interior part of the black hole is separated from the rest of the Universe. If ċ < 0, then the size of the Schwarzschild radius increases with time. The higher value of the speed of light in the very early Universe may have caused a large reduction in the probability of the creation of the primordial black holes and their population. The same analogy is also considered for charged black holes. PACS No.: 04.70.–s
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Ng, Ken K. Y., Gabriele Franciolini, Emanuele Berti, Paolo Pani, Antonio Riotto e Salvatore Vitale. "Constraining High-redshift Stellar-mass Primordial Black Holes with Next-generation Ground-based Gravitational-wave Detectors". Astrophysical Journal Letters 933, n. 2 (1 luglio 2022): L41. http://dx.doi.org/10.3847/2041-8213/ac7aae.
Testo completoAbstract (sommario):
Abstract The possible existence of primordial black holes in the stellar-mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population III stars, are expected to dominate at high redshifts (z ≳ 10). However, the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET) can access this distinctive feature in the merger rates as functions of redshift, allowing for direct measurement of the abundance of the two populations and hence for robust constraints on the abundance of primordial black holes. We simulate four months’ worth of data observed by a CE-ET detector network and perform hierarchical Bayesian analysis to recover the merger rate densities. We find that if the universe has no primordial black holes with masses of ( 10 M ⊙ ) , the projected upper limit on their abundance f PBH as a fraction of dark matter energy density may be as low as f PBH ∼ ( 10 − 5 ) , about two orders of magnitude lower than the current upper limits in this mass range. If instead f PBH ≳ 10−4, future gravitational-wave observations would exclude f PBH = 0 at the 95% credible interval.
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Mummery, Andrew, e Steven A. Balbus. "An upper observable black hole mass scale for tidal destruction events with thermal X-ray spectra". Monthly Notices of the Royal Astronomical Society 505, n. 2 (17 maggio 2021): 1629–44. http://dx.doi.org/10.1093/mnras/stab1141.
Testo completoAbstract (sommario):
ABSTRACT We comprehensively model the X-ray luminosity emergent from time-dependent relativistic accretion discs, developing analytical models of the X-ray luminosity of thermal disc systems as a function of black hole mass M, disc mass Md, and disc α-parameter. The X-ray properties of these solutions will be directly relevant for understanding tidal disruption event (TDE) observations. We demonstrate an extremely strong suppression of thermal X-ray luminosity from large mass black holes, LX ∼ exp (− m7/6), where m is a dimensionless mass, roughly the black hole mass in unity of 106M⊙. This strong suppression results in upper observable black hole mass limits, which we demonstrate to be of order Mlim ≃ 3 × 107M⊙, above which thermal X-ray emission will not be observable. This upper observable black hole mass limit is a function of the remaining disc parameters, and the full dependence can be described analytically (equation 82). We demonstrate that the current population of observed X-ray TDEs is indeed consistent with an upper black hole mass limit of order M ∼ 107M⊙, consistent with our analysis.
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Mummery, Andrew. "A maximum X-ray luminosity scale of disc-dominated tidal destruction events". Monthly Notices of the Royal Astronomical Society 504, n. 4 (26 aprile 2021): 5144–54. http://dx.doi.org/10.1093/mnras/stab1187.
Testo completoAbstract (sommario):
ABSTRACT We develop a model describing the dynamical and observed properties of disc-dominated tidal disruption events (TDEs) around black holes with the lowest masses (M ≲ few × 106M⊙). TDEs around black holes with the lowest masses are most likely to reach super-Eddington luminosities at early times in their evolution. By assuming that the amount of stellar debris that can form into a compact accretion disc is set dynamically by the Eddington luminosity, we make a number of interesting and testable predictions about the observed properties of bright soft-state X-ray TDEs and optically bright, X-ray dim TDEs. We argue that TDEs around black holes of the lowest masses will expel the vast majority of their gravitationally bound debris into a radiatively driven outflow. A large-mass outflow will obscure the innermost X-ray producing regions, leading to a population of low black hole mass TDEs that are only observed at optical and UV energies. TDE discs evolving with bolometric luminosities comparable to their Eddington luminosity will have near constant (i.e. black hole mass independent) X-ray luminosities, of order LX, max ≡ LM ∼ 1043 − 1044 erg s−1. The range of luminosity values stems primarily from the range of allowed black hole spins. A similar X-ray luminosity limit exists for X-ray TDEs in the hard (Compton scattering dominated) state, and we therefore predict that the X-ray luminosity of the brightest X-ray TDEs will be at the scale LM(a) ∼ 1043 − 1044 erg s−1, independent of black hole mass and accretion state. These predictions are in strong agreement with the properties of the existing population (∼40 sources) of observed TDEs.
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Postnov, Konstantin, e Alexander Kuranov. "Progenitors of binary black hole mergers detected by LIGO". Proceedings of the International Astronomical Union 12, S329 (novembre 2016): 118–25. http://dx.doi.org/10.1017/s1743921317002964.
Testo completoAbstract (sommario):
AbstractPossible formation mechanisms of massive close binary black holes that can merge in the Hubble time to produce powerful gravitational wave bursts detected during advanced LIGO O1 science run are briefly discussed. The pathways include the evolution from field low-metallicity massive binaries, the dynamical formation in globular clusters and primordial black holes. Low effective black hole spins inferred for LIGO GW150914 and LTV151012 events are discussed. Population synthesis calculations of the expected spin and chirp mass distributions from the standard field massive binary formation channel are presented for different metallicities (from zero-metal Population III stars up to solar metal abundance). We conclude that that merging binary black holes can contain systems from different formation channels, discrimination between which can be made with increasing statistics of mass and spin measurements from ongoing and future gravitational wave observations.
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Shao, Yong, e Xiang-Dong Li. "Population Synthesis of Black Hole X-Ray Binaries". Astrophysical Journal 898, n. 2 (3 agosto 2020): 143. http://dx.doi.org/10.3847/1538-4357/aba118.
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Tiwari, Vaibhav. "Exploring Features in the Binary Black Hole Population". Astrophysical Journal 928, n. 2 (1 aprile 2022): 155. http://dx.doi.org/10.3847/1538-4357/ac589a.
Testo completoAbstract (sommario):
Abstract Vamana is a mixture model framework that infers the astrophysical distribution of chirp mass, mass ratio, and spin component aligned with the orbital angular momentum for the binary black holes (BBH) population. We extend the mixing components in this framework to also model the redshift evolution of merger rate and report all the major one- and two-dimensional features in the BBH population using the 69 gravitational-wave signals detected with a false alarm rate <1 yr−1 in the third Gravitational-Wave Transient Catalog (GWTC-3). Endorsing our previous report and a recent corroborating report from LIGO Scientific, Virgo, and KAGRA Collaborations, we observe the chirp mass distribution has multiple peaks and a lack of mergers with chirp masses 10–12 M ⊙. In addition, we observe that aligned spins show mass dependence with heavier binaries exhibiting larger spins, the mass ratio shows a dependence on the chirp mass but not on the aligned spin, and the redshift evolution of the merger rate for the peaks in the mass distribution is disparate. These features possibly reflect the astrophysics associated with the BBH formation channels. However, additional observations are needed to improve our limited confidence in them.
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Dolgov, A., e K. Postnov. "Globular cluster seeding by primordial black hole population". Journal of Cosmology and Astroparticle Physics 2017, n. 04 (20 aprile 2017): 036. http://dx.doi.org/10.1088/1475-7516/2017/04/036.
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Ohsuga, Ken, Hajime Susa e Yosuke Uchiyama. "Instability of Population III Black Hole Accretion Disks". Publications of the Astronomical Society of Japan 59, n. 6 (25 dicembre 2007): 1235–41. http://dx.doi.org/10.1093/pasj/59.6.1235.
Testo completo
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Nitz, Alexander H., Collin D. Capano, Sumit Kumar, Yi-Fan Wang, Shilpa Kastha, Marlin Schäfer, Rahul Dhurkunde e Miriam Cabero. "3-OGC: Catalog of Gravitational Waves from Compact-binary Mergers". Astrophysical Journal 922, n. 1 (1 novembre 2021): 76. http://dx.doi.org/10.3847/1538-4357/ac1c03.
Testo completoAbstract (sommario):
Abstract We present the third open gravitational-wave catalog (3-OGC) of compact-binary coalescences, based on the analysis of the public LIGO and Virgo data from 2015 through 2019 (O1, O2, O3a). Our updated catalog includes a population of 57 observations, including 4 binary black hole mergers that had not been previously reported. This consists of 55 binary black hole mergers and the 2 binary neutron star mergers, GW170817 and GW190425. We find no additional significant binary neutron star or neutron star–black hole merger events. The most confident new detection is the binary black hole merger GW190925_232845, which was observed by the LIGO–Hanford and Virgo observatories with astro > 0.99 ; its primary and secondary component masses are 20.2 − 2.5 + 3.9 M ⊙ and 15.6 − 2.6 + 2.1 M ⊙ , respectively. We estimate the parameters of all binary black hole events using an up-to-date waveform model that includes both subdominant harmonics and precession effects. To enable deep follow up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the subthreshold population of candidates, and the posterior samples of our source parameter estimates.
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Ziółkowski, Janusz, e Krzysztof Belczyński. "On the apparent lack of Be X-ray binaries with black holes in the galaxy and in the Magellanic Clouds". Proceedings of the International Astronomical Union 6, S275 (settembre 2010): 329–30. http://dx.doi.org/10.1017/s1743921310016340.
Testo completoAbstract (sommario):
AbstractIn the Galaxy there are 67 Be X-ray binaries known to-date. Out of those, 45 host a neutron star, and for the reminder the nature of a companion is not known. None, so far, is known to host a black hole. This disparity is referred to as a missing Be – black hole X-ray binary problem. The stellar population synthesis calculations following the formation of Be X-ray binaries (Belczyński & Ziółkowski 2009) predict that the ratio of the binaries with neutron stars to the ones with black holes is rather high FNS/BH ~ 30–50. A comparison of this ratio with the number of confirmed Be – neutron star X-ray binaries (45) indicates that the expected number of Be – black hole X-ray binaries is of the order of only ~0–2. This is entirely consistent with the observed Galactic sample. Therefore, there is no problem of the missing Be+BH X-Ray Binaries for the GalaxyIn the Magellanic Clouds there are 94 Be X-ray binaries known to-date. Out of those, 60 host a neutron star. Again, none hosts a black hole. The stellar population synthesis calculations carried out specifically for the Magellanic Clouds (Ziółkowski & Belczyński 2010) predict that the ratio of the Be X-ray binaries with neutron stars to the ones with black holes is only FNS/BH ~ 10. This value is rather too low, as it implies the expected number of Be+BH X-ray binaries of the order of ~6, while none is observed. We found, that to remove the discrepancy, one has to take into account a different history of the star formation rate in the Magellanic Clouds, with the respect to the Galaxy. New stellar population synthesis calculations are currently being carried out.
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Wong, Thomas Hong Tsun, Hugo Pfister e Lixin Dai. "Revisiting the Rates and Demographics of Tidal Disruption Events: Effects of the Disk Formation Efficiency". Astrophysical Journal Letters 927, n. 1 (1 marzo 2022): L19. http://dx.doi.org/10.3847/2041-8213/ac5823.
Testo completoAbstract (sommario):
Abstract Tidal disruption events (TDEs) are valuable probes of the demographics of supermassive black holes as well as the dynamics and population of stars in the centers of galaxies. In this Letter, we focus on studying how debris disk formation and circularization processes can impact the possibility of observing prompt flares in TDEs. First, we investigate how the efficiency of disk formation is determined by the key parameters, namely, the black hole mass M BH, the stellar mass m ⋆, and the orbital penetration parameter β that quantifies how close the disrupted star would orbit around the black hole. Then we calculate the intrinsic differential TDE rate as a function of these three parameters. Combining these two results, we find that the rates of TDEs with prompt disk formation are significantly suppressed around lighter black holes, which provides a plausible explanation for why the observed TDE host black hole mass distribution peaks between 106 and 107 M ⊙. Therefore, the consideration of disk formation efficiency is crucial for recovering the intrinsic black hole demographics from TDEs. Furthermore, we find that the efficiency of the disk formation process also impacts the distributions of both stellar orbital penetration parameter and stellar mass observed in TDEs.
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Greene, Jenny E., e Luis C. Ho. "Local active black hole mass functions". Proceedings of the International Astronomical Union 2, S238 (agosto 2006): 87–90. http://dx.doi.org/10.1017/s1743921307004747.
Testo completoAbstract (sommario):
AbstractWhile black holes (BHs) are apparently a ubiquitous component of the nuclei of local spheroids, their role in galaxy evolution remains largely unknown. The tight correlations between galaxy spheroid properties and BH mass provide an important boundary condition for models of the coevolution of BHs and galaxies. Here we consider another important boundary condition: the local mass function of broad-line active galaxies. We use standard virial mass estimation techniques to examine the distribution of BH masses and accretion rates for active galaxies in the local universe, and we also compare the distribution of BH masses in local broad and narrow-line objects, and find that both populations have a characteristic mass of ∼107M⊙. Most importantly, this is the first BH mass function to consider BH with masses ∼106M⊙. The space density of this important population allows us to place constraints on potential mechanisms for the creation of seed BHs in the early Universe.
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Chen, Nianyi, Yueying Ni, Michael Tremmel, Tiziana Di Matteo, Simeon Bird, Colin DeGraf e Yu Feng. "Dynamical friction modelling of massive black holes in cosmological simulations and effects on merger rate predictions". Monthly Notices of the Royal Astronomical Society 510, n. 1 (26 novembre 2021): 531–50. http://dx.doi.org/10.1093/mnras/stab3411.
Testo completoAbstract (sommario):
ABSTRACT In this work, we establish and test methods for implementing dynamical friction (DF) for massive black hole pairs that form in large volume cosmological hydrodynamical simulations that include galaxy formation and black hole growth. We verify our models and parameters both for individual black hole dynamics and for the black hole population in cosmological volumes. Using our model of DF from collisionless particles, black holes can effectively sink close to the galaxy centre, provided that the black hole’s dynamical mass is at least twice that of the lowest mass resolution particles in the simulation. Gas drag also plays a role in assisting the black holes’ orbital decay, but it is typically less effective than that from collisionless particles, especially after the first billion years of the black hole’s evolution. DF from gas becomes less than $1{{\ \rm per\ cent}}$ of DF from collisionless particles for BH masses >107 M⊙. Using our best DF model, we calculate the merger rate down to z = 1.1 using an Lbox = 35 Mpc h−1 simulation box. We predict ∼2 mergers per year for z > 1.1 peaking at z ∼ 2. These merger rates are within the range obtained in previous work using similar resolution hydrodynamical simulations. We show that the rate is enhanced by factor of ∼2 when DF is taken into account in the simulations compared to the no-DF run. This is due to ${\gt}40{{\ \rm per\ cent}}$ more black holes reaching the centre of their host halo when DF is added.
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Davis, Benjamin L., e Zehao 泽灏 Jin 金. "Discovery of a Planar Black Hole Mass Scaling Relation for Spiral Galaxies". Astrophysical Journal Letters 956, n. 1 (1 ottobre 2023): L22. http://dx.doi.org/10.3847/2041-8213/acfa98.
Testo completoAbstract (sommario):
Abstract Supermassive black holes (SMBHs) are tiny in comparison to the galaxies they inhabit, yet they manage to influence and coevolve along with their hosts. Evidence of this mutual development is observed in the structure and dynamics of galaxies and their correlations with black hole mass (M •). For our study, we focus on relative parameters that are unique to only disk galaxies. As such, we quantify the structure of spiral galaxies via their logarithmic spiral-arm pitch angles (ϕ) and their dynamics through the maximum rotational velocities of their galactic disks (v max). In the past, we have studied black hole mass scaling relations between M • and ϕ or v max, separately. Now, we combine the three parameters into a trivariate M •–ϕ–v max relationship that yields best-in-class accuracy in prediction of black hole masses in spiral galaxies. Because most black hole mass scaling relations have been created from samples of the largest SMBHs within the most massive galaxies, they lack certainty when extrapolated to low-mass spiral galaxies. Thus, it is difficult to confidently use existing scaling relations when trying to identify galaxies that might harbor the elusive class of intermediate-mass black holes (IMBHs). Therefore, we offer our novel relationship as an ideal predictor to search for IMBHs and probe the low-mass end of the black hole mass function by utilizing spiral galaxies. Already with rotational velocities widely available for a large population of galaxies and pitch angles readily measurable from uncalibrated images, we expect that the M •–ϕ–v max fundamental plane will be a useful tool for estimating black hole masses, even at high redshifts.
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Bavera, Simone S., Tassos Fragos, Michael Zevin, Christopher P. L. Berry, Pablo Marchant, Jeff J. Andrews, Scott Coughlin et al. "The impact of mass-transfer physics on the observable properties of field binary black hole populations". Astronomy & Astrophysics 647 (marzo 2021): A153. http://dx.doi.org/10.1051/0004-6361/202039804.
Testo completoAbstract (sommario):
We study the impact of mass-transfer physics on the observable properties of binary black hole populations that formed through isolated binary evolution. We used the POSYDON framework to combine detailed MESA binary simulations with the COSMIC population synthesis tool to obtain an accurate estimate of merging binary black hole observables with a specific focus on the spins of the black holes. We investigate the impact of mass-accretion efficiency onto compact objects and common-envelope efficiency on the observed distributions of the effective inspiral spin parameter χeff, chirp mass Mchirp, and binary mass ratio q. We find that low common envelope efficiency translates to tighter orbits following the common envelope and therefore more tidally spun up second-born black holes. However, these systems have short merger timescales and are only marginally detectable by current gravitational-wave detectors as they form and merge at high redshifts (z ∼ 2), outside current detector horizons. Assuming Eddington-limited accretion efficiency and that the first-born black hole is formed with a negligible spin, we find that all non-zero χeff systems in the detectable population can come only from the common envelope channel as the stable mass-transfer channel cannot shrink the orbits enough for efficient tidal spin-up to take place. We find that the local rate density (z ≃ 0.01) for the common envelope channel is in the range of ∼17–113 Gpc−3 yr−1, considering a range of αCE ∈ [0.2, 5.0], while for the stable mass transfer channel the rate density is ∼25 Gpc−3 yr−1. The latter drops by two orders of magnitude if the mass accretion onto the black hole is not Eddington limited because conservative mass transfer does not shrink the orbit as efficiently as non-conservative mass transfer does. Finally, using GWTC-2 events, we constrained the lower bound of branching fraction from other formation channels in the detected population to be ∼0.2. Assuming all remaining events to be formed through either stable mass transfer or common envelope channels, we find moderate to strong evidence in favour of models with inefficient common envelopes.
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Rastello, Sara, Ugo N. di Carlo, Michela Mapelli, Nicola Giacobbo e Alessandro Ballone. "Black Hole dynamics in Young Star Clusters". Proceedings of the International Astronomical Union 14, S351 (maggio 2019): 490–93. http://dx.doi.org/10.1017/s174392131900680x.
Testo completoAbstract (sommario):
AbstractYoung star clusters are a promising environment for forming binary black holes. Such binaries may form dynamically or via binary star evolution or through the interplay of these two channels. To study these formation pathways, we have performed high precision direct N-body simulations of low-mass (M < 1000 M⊙) young star clusters. The simulations were carried out with the code Nbody6++GPU coupled with the population synthesis code MOBSE. Our results highlight the importance of dynamics to form massive black hole binaries even in low-mass young star clusters.
46
Sbarrato, T., G. Ghisellini, G. Giovannini e M. Giroletti. "Jetted radio-quiet quasars at z > 5". Astronomy & Astrophysics 655 (novembre 2021): A95. http://dx.doi.org/10.1051/0004-6361/202141827.
Testo completoAbstract (sommario):
We report on the JVLA observations of three high-redshift active galactic nuclei (AGNs) that have black hole masses estimated to be among the largest known. Two of them, SDSS J0100+2802 and SDSS J0306+1853 at redshift 6.326 and 5.363, respectively, are radio-quiet AGNs according to the classic definition, while the third (B2 1023+25 at z = 5.284) is a powerful blazar. The JVLA data clearly show a radio structure in the first source and a radio emission with a relatively steep radio spectrum in the second one, indicating the presence of a radio jet and a diffuse component. Therefore, being radio-quiet does not exclude the presence of a powerful relativistic jet, which has important consequences on population studies and on the ratio between jetted and non-jetted AGNs. We can estimate the viewing angle of these jets, and this allows us to find, albeit with some uncertainty, the density of black holes with a mass in excess of 1010 M⊙ at high redshifts. We found that their density in jetted AGNs is very large in the redshift bin 5–6 and comparable with the overall AGN population of the same optical luminosity. Jets might thus play a crucial role in the fast formation and evolution of the most massive black holes in the early Universe. They are more common than what is expected from wide radio surveys with milliJansky flux sensitivity. Deeper JVLA or very-long-baseline interferometry observations are key to discovering a possible relativistic jet population hiding in plain sight at very high redshift. The discovery of powerful relativistic jets associated with the most massive black holes in the early Universe revives the question: is the jet instrumental for a rapid growth of the black hole or, instead, is the black hole mass the main driver for the jet formation?
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Baron, Dalya. "Probing black hole - host galaxy scaling relations with obscured type II AGN". Proceedings of the International Astronomical Union 15, S356 (ottobre 2019): 365. http://dx.doi.org/10.1017/s1743921320003373.
Testo completoAbstract (sommario):
AbstractThe scaling relations between supermassive black holes and their host galaxy properties are of fundamental importance in the context black hole-host galaxy co-evolution throughout cosmic time. Beyond the local universe, such relations are based on black hole mass estimates in type I AGN. Unfortunately, for this type of objects the host galaxy properties are more difficult to obtain since the AGN dominates the observed flux in most wavelength ranges. In this poster I will present a new correlation we discovered between the narrow L([OIII])/L(Hβ) line ratio and the FWHM(broad Hα). This scaling relation ties the kinematics of the gas clouds in the broad line region to the ionization state of gas in the narrow line region, connecting the properties of gas clouds kiloparsecs away from the black hole to material gravitationally bound to it on sub-parsec scales. This relation can be used to estimate black hole masses from narrow emission lines only, and thus brings the missing piece required to estimate black hole masses in obscured type II AGN. Using this technique, we estimate the black hole mass of about 10,000 type II AGN, and present, for the first time, M(BH)-sigma and M(BH)-M(stars) scaling relations for this population. These relations are remarkably consistent with those observed for type I AGN, suggesting that this new method may perform as reliably as the classical estimate used in non-obscured type I AGN. These findings open a new window for studies of black hole-host galaxy co-evolution throughout cosmic time.
48
Langer, N., C. Schürmann, K. Stoll, P. Marchant, D. J. Lennon, L. Mahy, S. E. de Mink et al. "Properties of OB star−black hole systems derived from detailed binary evolution models". Astronomy & Astrophysics 638 (giugno 2020): A39. http://dx.doi.org/10.1051/0004-6361/201937375.
Testo completoAbstract (sommario):
Context. The recent gravitational wave measurements have demonstrated the existence of stellar mass black hole binaries. It is essential for our understanding of massive star evolution to identify the contribution of binary evolution to the formation of double black holes. Aims. A promising way to progress is investigating the progenitors of double black hole systems and comparing predictions with local massive star samples, such as the population in 30 Doradus in the Large Magellanic Cloud (LMC). Methods. With this purpose in mind, we analysed a large grid of detailed binary evolution models at LMC metallicity with initial primary masses between 10 and 40 M⊙, and identified the model systems that potentially evolve into a binary consisting of a black hole and a massive main-sequence star. We then derived the observable properties of such systems, as well as peculiarities of the OB star component. Results. We find that ∼3% of the LMC late-O and early-B stars in binaries are expected to possess a black hole companion when stars with a final helium core mass above 6.6 M⊙ are assumed to form black holes. While the vast majority of them may be X-ray quiet, our models suggest that these black holes may be identified in spectroscopic binaries, either by large amplitude radial velocity variations (≳50 km s−1) and simultaneous nitrogen surface enrichment, or through a moderate radial velocity (≳10 km s−1) and simultaneous rapid rotation of the OB star. The predicted mass ratios are such that main-sequence companions can be excluded in most cases. A comparison to the observed OB+WR binaries in the LMC, Be and X-ray binaries, and known massive black hole binaries supports our conclusion. Conclusions. We expect spectroscopic observations to be able to test key assumptions in our models, with important implications for massive star evolution in general and for the formation of double black hole mergers in particular.
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Draghis, Paul A., Mayura Balakrishnan, Jon M. Miller, Edward Cackett, Andrew C. Fabian, James Miller-Jones, Mason Ng, John C. Raymond, Mark Reynolds e Abderahmen Zoghbi. "The Spin of a Newborn Black Hole: Swift J1728.9-3613". Astrophysical Journal 947, n. 1 (1 aprile 2023): 39. http://dx.doi.org/10.3847/1538-4357/acc1c8.
Testo completoAbstract (sommario):
Abstract The origin and distribution of stellar-mass black hole spins are a rare window into the progenitor stars and supernova events that create them. Swift J1728.9-3613 is an X-ray binary, likely associated with the supernova remnant (SNR) G351.9-0.9. An NuSTAR X-ray spectrum of this source during its 2019 outburst reveals reflection from an accretion disk extending to the innermost stable circular orbit. Modeling of the relativistic Doppler shifts and gravitational redshifts imprinted on the spectrum measures a dimensionless spin parameter of a = 0.86 ± 0.02 (1σ confidence), a small inclination angle of the inner accretion disk θ < 10°, and a subsolar iron abundance in the disk A Fe < 0.84. This high spin value rules out a neutron star primary at the 5σ level of confidence. If the black hole is located in a still visible SNR, it must be young. Therefore, we place a lower limit on the natal black hole spin of a > 0.82, concluding that the black hole must have formed with a high spin. This demonstrates that black hole formation channels that leave an SNR, and those that do not (e.g., Cyg X-1), can both lead to high natal spin with no requirement for subsequent accretion within the binary system. Emerging disparities between the population of high-spin black holes in X-ray binaries and the low-spin black holes that merge in gravitational wave events may therefore be explained in terms of different stellar conditions prior to collapse, rather than different environmental factors after formation.
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Wu, Chong, Tao Wu, Kaiyuan Fu, Yuan Zhu, Yongbo Li, Wangyong He e Shengwen Tang. "AMOBH: Adaptive Multiobjective Black Hole Algorithm". Computational Intelligence and Neuroscience 2017 (2017): 1–19. http://dx.doi.org/10.1155/2017/6153951.
Testo completoAbstract (sommario):
This paper proposes a new multiobjective evolutionary algorithm based on the black hole algorithm with a new individual density assessment (cell density), called “adaptive multiobjective black hole algorithm” (AMOBH). Cell density has the characteristics of low computational complexity and maintains a good balance of convergence and diversity of the Pareto front. The framework of AMOBH can be divided into three steps. Firstly, the Pareto front is mapped to a new objective space called parallel cell coordinate system. Then, to adjust the evolutionary strategies adaptively, Shannon entropy is employed to estimate the evolution status. At last, the cell density is combined with a dominance strength assessment called cell dominance to evaluate the fitness of solutions. Compared with the state-of-the-art methods SPEA-II, PESA-II, NSGA-II, and MOEA/D, experimental results show that AMOBH has a good performance in terms of convergence rate, population diversity, population convergence, subpopulation obtention of different Pareto regions, and time complexity to the latter in most cases.