scholarly journals Black Hole Demographics: Statistical Characteristics of Accreting Black Holes

2009 ◽  
Vol 5 (S267) ◽  
pp. 213-222
Author(s):  
Hagai Netzer

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.

2019 ◽  
Vol 15 (S359) ◽  
pp. 57-61
Author(s):  
Michael Brotherton ◽  
Jaya Maithil ◽  
Adam Myers ◽  
Ohad Shemmer ◽  
Brandon Matthews ◽  
...  

AbstractQuasar black hole masses are most commonly estimated using broad emission lines in single epoch spectra based on scaling relationships determined from reverberation mapping of small samples of low-redshift objects. Several effects have been identified requiring modifications to these scaling relationships, resulting in significant reductions of the black hole mass determinations at high redshift. Correcting these systematic biases is critical to understanding the relationships among black hole and host galaxy properties. We are completing a program using the Gemini North telescope, called the Gemini North Infrared Spectrograph (GNIRS) Distant Quasar Survey (DQS), that has produced rest-frame optical spectra of about 200 high-redshift quasars (z = 1.5–3.5). The GNIRS-DQS will produce new and improved ultraviolet-based black hole mass and accretion rate prescriptions, as well as new redshift prescriptions for velocity zero points of high-z quasars, necessary to measure feedback.


2020 ◽  
Vol 501 (1) ◽  
pp. 269-280
Author(s):  
Xuheng Ding ◽  
Tommaso Treu ◽  
Simon Birrer ◽  
Adriano Agnello ◽  
Dominique Sluse ◽  
...  

ABSTRACT One of the main challenges in using high-redshift active galactic nuclei (AGNs) to study the correlations between the mass of a supermassive black hole ($\mathcal {M}_{\rm BH}$) and the properties of its active host galaxy is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed AGNs with deep Hubble Space Telescope imaging, using the lens modelling code lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. $\mathcal {M}_{\rm BH}$ are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGNs, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGNs is small and thus they provide mostly a consistency check on systematic errors related to resolution for non-lensed AGNs. However, the number of known lensed AGNs is expected to increase dramatically in the next few years, through dedicated searches in ground- and space-based wide-field surveys, and they may become a key diagnostic of black holes and galaxy co-evolution.


2019 ◽  
Vol 15 (S356) ◽  
pp. 376-376
Author(s):  
Ingyin Zaw

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.


2009 ◽  
Vol 5 (S267) ◽  
pp. 151-160 ◽  
Author(s):  
Bradley M. Peterson

AbstractWe review briefly direct and indirect methods of measuring the masses of black holes in galactic nuclei, and then focus attention on supermassive black holes in active nuclei, with special attention to results from reverberation mapping and their limitations. We find that the intrinsic scatter in the relationship between the AGN luminosity and the broad-line region size is very small, ~0.11 dex, comparable to the uncertainties in the better reverberation measurements. We also find that the relationship between reverberation-based black hole masses and host-galaxy bulge luminosities also seems to have surprisingly little intrinsic scatter, ~0.17 dex. We note, however, that there are still potential systematics that could affect the overall mass calibration at the level of a factor of a few.


Author(s):  
Pavel Kroupa ◽  
Ladislav Subr ◽  
Tereza Jerabkova ◽  
Long Wang

Abstract The observation of quasars at very high redshift such as Pōniuā’ena is a challenge for models of super-massive black hole (SMBH) formation. This work presents a study of SMBH formation via known physical processes in star-burst clusters formed at the onset of the formation of their hosting galaxy. While at the early stages hyper-massive star-burst clusters reach the luminosities of quasars, once their massive stars die, the ensuing gas accretion from the still forming host galaxy compresses its stellar black hole (BH) component to a compact state overcoming heating from the BH–BH binaries such that the cluster collapses, forming a massive SMBH-seed within about a hundred Myr. Within this scenario the SMBH–spheroid correlation emerges near-to-exactly. The highest-redshift quasars may thus be hyper-massive star-burst clusters or young ultra-compact dwarf galaxies (UCDs), being the precursors of the SMBHs that form therein within about 200 Myr of the first stars. For spheroid masses ≲ 109.6 M⊙ a SMBH cannot form and instead only the accumulated nuclear cluster remains. The number evolution of the quasar phases with redshift is calculated and the possible problem of missing quasars at very high redshift is raised. SMBH-bearing UCDs and the formation of spheroids are discussed critically in view of the high redshift observations. A possible tension is found between the high star-formation rates (SFRs) implied by downsizing and the observed SFRs, which may be alleviated within the IGIMF theory and if the downsizing times are somewhat longer.


2020 ◽  
Vol 497 (4) ◽  
pp. 5292-5308 ◽  
Author(s):  
Paul Torrey ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
Daniel Anglés-Alcázar ◽  
Eliot Quataert ◽  
...  

ABSTRACT Accreting black holes can drive fast and energetic nuclear winds that may be an important feedback mechanism associated with active galactic nuclei (AGN). In this paper, we implement a scheme for capturing feedback from these fast nuclear winds and examine their impact in simulations of isolated disc galaxies. Stellar feedback is modelled using the Feedback In Realistic Environments (fire) physics and produces a realistic multiphase interstellar medium (ISM). We find that AGN winds drive the formation of a low-density, high-temperature central gas cavity that is broadly consistent with analytic model expectations. The effects of AGN feedback on the host galaxy are a strong function of the wind kinetic power and momentum. Low- and moderate-luminosity AGN do not have a significant effect on their host galaxy: the AGN winds inefficiently couple to the ambient ISM and instead a significant fraction of their energy vents in the polar direction. For such massive black holes, accretion near the Eddington limit can have a dramatic impact on the host galaxy ISM: if AGN wind feedback acts for ≳20–30 Myr, the inner ∼1–10 kpc of the ISM is disrupted and the global galaxy star formation rate is significantly reduced. We quantify the properties of the resulting galaxy-scale outflows and find that the radial momentum in the outflow is boosted by a factor of ∼2–3 relative to that initially supplied in the AGN wind for strong feedback scenarios, decreasing below unity for less energetic winds. In contrast to observations, however, the outflows are primarily hot, with very little atomic or molecular gas. We conjecture that merging galaxies and high-redshift galaxies, which have more turbulent and thicker discs and very different nuclear gas geometries, may be even more disrupted by AGN winds than found in our simulations.


2019 ◽  
Vol 491 (4) ◽  
pp. 4973-4992
Author(s):  
C DeGraf ◽  
D Sijacki

ABSTRACT We study how statistical properties of supermassive black holes depend on the frequency and conditions for massive seed formation in cosmological simulations of structure formation. We develop a novel method to recalculate detailed growth histories and merger trees of black holes within the framework of the Illustris simulation for several seed formation models, including a physically motivated model where black hole seeds only form in progenitor galaxies that conform to the conditions for direct collapse black hole formation. While all seed models considered here are in a broad agreement with present observational constraints on black hole populations from optical, UV, and X-ray studies, we find that they lead to widely different black hole number densities and halo occupation fractions, which are currently observationally unconstrained. In terms of future electromagnetic spectrum observations, the faint-end quasar luminosity function and the low-mass-end black hole–host galaxy scaling relations are very sensitive to the specific massive seed prescription. Specifically, the direct collapse model exhibits a seeding efficiency that decreases rapidly with cosmic time and produces much fewer black holes in low-mass galaxies, in contrast to the original Illustris simulation. We further find that the total black hole merger rate varies by more than one order of magnitude for different seed models, with the redshift evolution of the chirp mass changing as well. Supermassive black hole merger detections with LISA and International Pulsar Timing Array may hence provide the most direct means of constraining massive black hole seed formation in the early Universe.


1989 ◽  
Vol 134 ◽  
pp. 233-239
Author(s):  
R. D. Blandford

The observed evolutionary behavior of active galactic nuclei is compatible with a model in which black holes form in the nuclei of new-born galaxies and then grow at a rate limited by both radiation pressure and the supply of gas. Individual sources become more luminous with time as long as they are being fueled. However, the rapid decrease in the mean rate of supply of gas causes a strong decline in the space density of active objects. Nearby galaxies should harbor modest size (∼ 106 – 108 M⊙) black holes. It is suggested that the gas that fuels high redshift quasars is mostly derived from the host galaxy.


Daedalus ◽  
2014 ◽  
Vol 143 (4) ◽  
pp. 103-113 ◽  
Author(s):  
Scott Tremaine

Quasars emit more energy than any other object in the universe, yet are not much bigger than our solar system. Quasars are powered by giant black holes of up to ten billion (1010) times the mass of the sun. Their enormous luminosities are the result of frictional forces acting upon matter as it spirals toward the black hole, heating the gas until it glows. We also believe that black holes of one million to ten billion solar masses – dead quasars – are present at the centers of most galaxies, including our own. The mass of the central black hole appears to be closely related to other properties of its host galaxy, such as the total mass in stars, but the origin of this relation and the role that black holes play in the formation of galaxies are still mysteries.


2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Giuseppe Lodato

I review the recent progresses that have been obtained, especially through the use of high-resolution numerical simulations, on the dynamics of self-gravitating accretion discs. A coherent picture is emerging, where the disc dynamics is controlled by a small number of parameters that determine whether the disc is stable or unstable, whether the instability saturates in a self-regulated state or runs away into fragmentation, and whether the dynamics is local or global. I then apply these concepts to the case of AGN discs, discussing the implications of such evolution on the feeding of supermassive black holes. Nonfragmenting, self-gravitating discs appear to play a fundamental role in the process of formation of massive black hole seeds at high redshift ( 10–15) through direct gas collapse. On the other hand, the different cooling properties of the interstellar gas at low redshifts determine a radically different behaviour for the outskirts of the accretion discs feeding typical AGNs. Here the situation is much less clear from a theoretical point of view, and while several observational clues point to the important role of massive discs at a distance of roughly a parsec from their central black hole, their dynamics is still under debate.


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