We present a series of simulations of the self--regulated growth of supermassive black holes (SMBHs) in galaxies via three different fueling mechanisms: major mergers, minor mergers, and disk instabilities. The SMBHs in all three scenarios follow the same black hole fundamental plane (BHFP) and correlation with bulge binding energy seen in simulations of major mergers, and observed locally. Furthermore, provided that the total gas supply is significantly larger than the mass of the SMBH, its limiting mass is not influenced by the amount of gas available or the efficiency of black hole growth. This supports the assertion that SMBHs accrete until they reach a critical mass at which feedback is sufficient to unbind the gas locally, terminating the inflow and stalling further growth. At the same time, while minor and major mergers follow the same projected correlations (e.g., the $M_{BH}-σ$ and Magorrian relations), SMBHs grown via disk instabilities do not, owing to structural differences between the host bulges. This finding is supported by recent observations of SMBHs in pseudobulges and bulges in barred systems, as compared to those hosted by classical bulges. Taken together, this provides support for the BHFP and binding energy correlations as being more "fundamental" than other proposed correlations in that they reflect the physical mechanism driving the co-evolution of SMBHs and spheroids.
We postulate that supermassive black-holes grow in the centers of galaxies until they unbind the galactic gas that feeds them. We show that the corresponding self-regulation condition yields a correlation between black-hole mass (Mbh) and galaxy velocity dispersion (sigma) as inferred in the local universe, and recovers the observed optical and X-ray luminosity functions of quasars at redshifts up to z~6 based on the hierarchical evolution of galaxy halos in a Lambda-CDM cosmology. With only one free parameter and a simple algorithm, our model yields the observed evolution in the number densit…
We present a simple scenario where the formation of galactic bulges was regulated by the dark halo gravity and regulated the growth of the central supermassive black hole. Assuming the angular momentum is low, we suggest that bulges form in a runaway collapse due to the "gravothermal" instability once the central gas density or pressure exceeds certain threshold (Xu & Zhao 2007). We emphasize that the threshold is nearly universal, set by the background NFW dark matter gravity $g_{DM} \sim 1.2 \times 10^{-8}{\rm cm} {\rm sec}^{-2}$ in the central cusps of halos. Unlike known thresholds for gra…
We present an optical, X-ray, and radio analysis of the starburst in the Abell 1835 cluster's central cD galaxy. The dense gas surrounding the galaxy is radiating X-rays with a luminosity of ~1E45 erg/s consistent with a cooling rate of ~1000-2000 solar masses per year. However, Chandra and XMM-Newton observations find less than 200 solar masses per year of gas cooling below ~2 keV, a level that is consistent with the cD's current star formation rate of 100-180 solar masses per year. One or more heating agents (feedback) must then be replenishing the remaining radiative losses. The heat fluxes…
The evolution of a supermassive black hole in the center of galaxy is considered. We analyze the kinetic equation describing relaxation processes associated with stellar encounters. The initial distribution function of stars is assumed to be isothermal, and it changes in accordance with consumption of stars by the black hole. We calculate the consumption rate and obtain the law of growth of supermassive black hole, i.e. the dependence of the black hole mass on time and on the velocity dispersion of stars. The obtained values of mean black hole mass and mean rate of stars consumption by a black…
The observed relation between central black hole mass and spheroid velocity dispersion is interpreted in terms of a self-regulation model that incorporates a viscous Keplerian accretion disk to feed the black hole, embedded in a massive, self-gravitating star forming disk that eventually populates the spheroid. The model leads to a constant ratio between black hole mass and spheroid mass which is equal to the inverse of the critical Reynolds number for the onset of turbulence in the accretion disk surrounding the central black hole. Applying the fundamental plane correlation for spheroids, we …
We investigate the effect of a disc-driven jet on the accretion growth of cosmological supermassive black holes (SMBHs). The presence of a jet enhances the mass growth rate because for a given luminosity, the mass accretion rate, is higher (or equivalently, the radiative efficiency e_r is lower for a fixed mass accretion rate) than that predicted by standard accretion disc theory. As jets carry away very little of the accreting matter, a larger proportion of the rest mass can reach the black hole during episodes of jet activity. We show quantitatively that the conditions required to grow a rap…
HII regions surrounding supermassive black holes (BHs) in an otherwise still neutral intergalactic medium (IGM) are likely to be the most easily detectable sources by future 21cm experiments like LOFAR. We have made predictions for the size distribution of such HII regions for several physically motivated models for BH growth at high redshift and compared this to the expected LOFAR sensitivity to these sources. The number of potentially detectable HII regions does not only depend on the ionisation state of the intergalactic medium and the decoupling of the spin temperature of the neutral hydro…
The recently confirmed correlation between the mass of SMBH and bulges of galaxies (and their central velocity dispersion), suggest a common formation scenario for galaxies and their central black holes. Common fueling can be invoked through internal dynamical processes, external accretion, and hierarchical merging of structures. The success of recent theories is reviewed, as the self-regulated growth of both bulges and SMBHs, the predicted AGN statistics, when activity is triggered by accretion and mergers, the predicted frequency of binary SMBH and consequences. In particular, the SMBH growt…
Recent studies have shown that during their coalescence, binary supermassive black holes (SMBHs) experience a gravitational recoil with velocities of 100 km/s < v(kick) < 600 km/s. These velocities exceed the escape velocity v(esc) from typical dark matter (DM) halos at high-redshift (z>6), and therefore put constraints on scenarios in which early SMBHs grow at the centers of DM halos. Here we quantify these constraints for the most distant known SMBHs, with inferred masses in excess of 10^9 M(sun), powering the bright quasars discovered in the Sloan Digital Sky Survey at z>6. We assume that t…
Supermassive black holes underwent periods of exponential growth during which we seem them as quasars in the distant Universe. The summed emission from these quasars generates the cosmic X-ray background, the spectrum of which has been used to argue that most black-hole growth is obscured. There are clear examples of obscured black-hole growth in the form of `type-2' quasars, but their numbers are fewer than expected from modelling of the X-ray background. Here we report on the direct detection of a population of distant type-2 quasars which is at least comparable in size to the well-known uno…
We study the demographics of supermassive black holes (SMBHs) in the local and high-z universe with hard X-ray luminosity functions (HXLFs) of AGNs. First, we compare the mass accretion history at z>0 with optical luminosity functions (OLFs) and that with HXLFs. We consider the constraints on parameters of mass accretion (energy conversion efficiency and Eddington ratio) and conclude that the constraints based on HXLFs are more adequate rather than that based on OLFs. The sub-Eddington case is allowed only when we use HXLFs. Next, we estimate the upper limit of the cumulative mass density of S…
We present an alternative method to X-ray surveys for hunting down the high-redshift type-2 quasar population, using Spitzer and VLA data on the Spitzer First Look Survey. By demanding objects to be bright at 24 microns but faint at 3.6 microns, and combining this with a radio criterion, we find 21 type-2 radio-quiet quasar candidates at the epoch at which the quasar activity peaked. Optical spectroscopy with the WHT confirmed 10 of these objects to be type-2s with 1.4 < z < 4.2 while the rest are blank. There is no evidence for contamination in our sample, and we postulate that our 11 blank-s…
Aims: We investigate the cosmological growth of dark halos and follow the consequences of coeval growth for the accretion history of associated supermassive black holes. Methods: The Press-Schechter approximation is used to obtain an analytic expression for the mean rate of growth of dark matter halos. Dark halo accretion rates are compared with numerical work and the consequences for understanding AGN evolution are described. Results: The mean accretion rate onto dark matter halos is shown to have a simple analytic form that agrees with previous numerical work and that may easily be calculate…
A novel mechanism to build up a supermassive black hole (SMBH) is proposed. Here, relativistic radiation-hydrodynamic processes are considered from a galactic scale to a horizon scale. In the present scenario, the mass of a SMBH is predicted to be in proportion to the bulge mass, and it turns out that the SMBH-to-bulge mass ratio is basically determined by the nuclear energy conversion efficiency from hydrogen to helium, $ε=0.007$. The BH hierarchy is also addressed in relation to the BH formation in globular clusters. Futhermore, a new picture for QSO formation is proposed based on the presen…
Based on a high resolution cosmological n-body simulation, we track the hierarchical growth of black holes in galaxy clusters from z=20 to z=0. We present a census of black holes as function of redshift and will determine their mass assembly history under a variety of assumptions regarding the importance of gas accretion in black hole growth, from early supercritical Eddington accretion to gas-poor hierarchical assembly. Following a galaxy merger, black holes are expected to form, inspiral and merge after strongly radiating energy via gravitational waves. For each binary black hole inspiral an…
The strong correlation between the mass of the central supermassive black hole (SMBH) and the bulge in some galaxies and quasars implies that the formation of the black hole is somehow linked to the bulge. The measurement of metallicity by NV/CIV or NV/HeII in quasars allows to discuss a possible way of formation of the black hole. In this Letter we trace the metallicity along the possible routes in Rees' diagram in order to test the ways by which SMBHs can form. We derive a relation between the metallicity and the mass of the SMBH as $Z\propto M_{BH}$ based on the numerical simulation of the …
Understanding how seed black holes grow into intermediate and supermassive black holes (IMBHs and SMBHs, respectively) has important implications for the duty-cycle of active galactic nuclei (AGN), galaxy evolution, and gravitational wave astronomy. Most studies of the cosmological growth and merger history of black holes have used semianalytic models and have concentrated on SMBH growth in luminous galaxies. Using high resolution cosmological N-body simulations, we track the assembly of black holes over a large range of final masses -- from seed black holes to SMBHs -- over widely varying dyn…
We present an analysis of the growth of black holes through accretion and bulges through star formation in 33 galaxies at the centers of cooling flows. Most of these systems show evidence of cavities in the intracluster medium (ICM) inflated by radio jets emanating from their active galactic nuclei (AGN). We present a new and extensive analysis of X-ray cavities in these systems. We find that AGN are energetically able to balance radiative losses (cooling) from the ICM in more than half of our sample. Using a subsample of 17 systems, we examine the relationship between cooling and star formati…
We report on a calculation of the growth of the mass of supermassive black holes at galactic centers from dark matter and Eddington - limited baryonic accretion. Assuming that dark matter halos are made of fermions and harbor compact degenerate Fermi balls of masses from $10^{3}M_{\odot}$ to $10^{6}M_{\odot}$, we find that dark matter accretion can boost the mass of seed black holes from about $\sim 5M_{\odot}$ to $10^{3-4}M_{\odot}$ black holes, which then grow by Eddington - limited baryonic accretion to supermassive black holes of $10^{6 - 9}M_{\odot}$. We then show that the formation of th…
We consider the consequences of SIDM for a velocity dependent cross section per unit mass. Accretion of SIDM onto seed black holes can produce supermassive black holes that are too large for certain combinations of parameters,which is used to obtain a new constraint on the dark matter interaction. Constraints due to other considerations are presented and previous ones are generalized. The black hole constraint is extremely sensitive to the slope α, of the inner density profile of dark halos. For the most probable value of α=1.3, there exists a narrow range in parameter space, such that all con…
We discuss the role of feedback via photoionization and Compton heating in the co-evolution of massive black holes at the center of spheroidal galaxies and their stellar and gaseous components. We first assess the energetics of the radiative feedback from a typical quasar on the ambient interstellar gas. We then demonstrate that the observed Mbh-sigma relation could be established at a relatively early epoch in galactic evolution when the formation of the stellar bulge was almost completed and the gas-to-stars mass ratio was reduced to a low level ~0.01 such that cooling could not keep up with…
We show that the observed scatter in the relations between the mass of supermassive black holes (SMBHs), M_bh, and the velocity dispersion sigma or mass M_sph of their host spheroid, place interesting constraints on the process that regulates SMBH growth in galaxies. When combined with the observed properties of early-type SDSS galaxies, the observed intrinsic scatters imply that SMBH growth is regulated by the spheroid velocity dispersion rather than its mass. The M_bh-M_sph relation is therefore a by-product of a more fundamental M_bh-sigma relation. We construct a theoretical model for the …
Massive tori with $\approx 10^{8-9}M_{\odot}$ are predicted to extend on $\sim $100 pc scale around the centre of elliptical galaxy progenitors by a model of a supermassive black hole (SMBH) growth coeval to the spheroidal population of the host galaxy. Direct detection of such massive tori would cast light on a key physical condition that allows the rapid growth of SMBHs and the appearance of QSOs at high redshift. For this reason, we examine the detectability of such structures at substantial redshift with the Atacama Large Millimeter Array (ALMA). We propose that submillimeter galaxies (SMG…
In this paper, we address whether the growth of supermassive black-holes has kept pace with the process of galaxy assembly. For this purpose, we first searched the Hubble Ultra Deep Field (HUDF) for "tadpole galaxies", which have a knot at one end and an extended tail. They appear dynamically unrelaxed -- presumably early-stage mergers -- and make up ~6% of the field galaxy population. Their redshift distribution follows that of field galaxies, indicating that -- if tadpole galaxies are indeed dynamically young -- the process of galaxy assembly generally kept up with the reservoir of field gal…
We argue that the velocity dispersions and masses of galactic bulges and spheroids are byproducts of the feedback that regulates rapid black hole growth in protogalaxies. We suggest that the feedback energy liberated by accretion must pass through the accreting material, in an energy-conserving flux close-in and a momentum-conserving flux further out. If the inflowing gas dominates the gravitational potential outside the Bondi radius, feedback from Eddington-limited accretion drives the density profile of the gas to that of a singular isothermal sphere. We find that the velocity dispersion ass…
Simulations of binary black hole mergers indicate that asymmetrical gravitational wave (GW) emission can cause black holes to recoil at speeds up to thousands of km/s. These GW recoil events can dramatically affect the coevolution of recoiling supermassive black holes (SMBHs) and their host galaxies. However, theoretical studies of SMBH-galaxy evolution almost always assume a stationary central black hole. In light of the numerical results on GW recoil velocities, we relax that assumption here and consider the consequences of recoil for SMBH evolution. We follow the trajectories of SMBHs eject…
We present results from an extensive set of simulations of gravitational fragmentation in the presence of magnetic fields and ambipolar diffusion. The average fragmentation spacing in the nonlinear phase of evolution is in excellent agreement with the prediction of linear perturbation theory. The time scale for nonlinear growth and runaway of the first core is $\approx 10$ times the calculated growth time $\taugm$ of the eigenmode with minimum growth time, when starting from a uniform background state with small-amplitude white-noise perturbations. Subcritical and transcritical models typicall…
The influence of dark matter (DM) on the growth of supermassive black holes (SMBHs) in galaxies is studied. It is shown that gravitational scattering of DM particles on bulge stars leads to diffusion of DM in phase space {m, m_z, I} ('m' denotes the angular momentum and 'I' is the radial action). Appropriate diffusion coefficients are calculated for different bulge models, and it is argued that the diffusion along 'm' axis is the most important effect. It is shown that this process leads to noticeable flow of DM into the black hole (BH), resulting in its power-law growth: M_{bh} ~ t^{9/16}. Co…
Supermassive Black Holes are the most entropic objects found in the universe. The Holographic Bound (HB) to the entropy is used to constrain their formation time with initial masses $\sim{10}^{6-8}M_{\odot}$, as inferred from observations. We find that the entropy considerations are more limiting than causality for this "direct" formation. Later we analyze the possibility of SMBHs growing from seed black holes. The growth of the initial mass is studied in the case of accretion of pure radiation and quintessence fields, and we find that there is a class of models that may allow this metamorphos…
We discuss currently available observational constraints on the reionization history of the intergalactic medium (IGM), and the extent to which accreting black holes (BHs) can help explain these observations. We show new evidence, based on the combined statistics of Lyman alpha and beta absorption in quasar spectra, that the IGM contains a significant amount of neutral hydrogen, and is experiencing rapid ionization around redshift z=6. However, we argue that quasar BHs, even faint ones that are below the detection thresholds of existing optical surveys, are unlikely to drive the evolution of t…
We consider the distribution of local supermassive black hole Eddington ratios and accretion rates, accounting for the dependence of radiative efficiency and bolometric corrections on the accretion rate. We find that black hole mass growth, both of the integrated mass density and the masses of most individual objects, must be dominated by an earlier, radiatively efficient, high accretion rate stage, and not by the radiatively inefficient low accretion rate phase in which most local supermassive black holes are currently observed. This conclusion is particularly true of supermassive black holes…
We describe a mechanism by which supermassive black holes can form directly in the nuclei of protogalaxies, without the need for seed black holes left over from early star formation. Self-gravitating gas in dark matter halos can lose angular momentum rapidly via runaway, global dynamical instabilities, the so-called "bars within bars" mechanism. This leads to the rapid buildup of a dense, self-gravitating core supported by gas pressure - surrounded by a radiation pressure-dominated envelope - which gradually contracts and is compressed further by subsequent infall. These conditions lead to suc…
We present a comprehensive synthesis model for the AGN evolution and the growth of supermassive black holes in the Universe. We solve the continuity equation for SMBH mass function using the locally determined one as a boundary condition, and the hard X-ray luminosity function as tracer of the AGN growth rate distribution, supplemented with a luminosity-dependent bolometric correction and an absorbing column distribution. Differently from most previous semi-analytic and numerical models, we do not assume any specific distribution of Eddington ratios, rather we determine it empirically by coupl…
I present a new method to unveil the history of cosmic accretion and the build-up of Supermassive Black Holes (SMBH) in the nuclei of galaxies, based on observations of the evolving radio and (hard) X-ray luminosity functions of AGN. The fundamental plane of black hole activity discovered by Merloni, Heinz & Di Matteo (2003) is used as a mass and accretion rate estimator. I adopt the local BH mass function as a boundary condition to integrate backwards in time the continuity equation for the SMBH evolution, neglecting the role of mergers. Under the most general assumption that accretion procee…
The relationship between galaxies and supermassive black holes (SMBH) found in their cores plays a key role in the formation and evolution of both of these major constituents of the universe, as well as the evolution of the intergalactic medium. Neither can be fully understood on their own, and studies of galaxy and SMBH co-formation and co-evolution are now among the central topics of research in cosmology. Yet the very origins, and the early growth phases of the SMBH are still not firmly established. We review our current understanding of the relevant processes and their astrophysical and co…
The correlation between the mass of supermassive black holes in galaxy nuclei and the mass of the galaxy spheroids or bulges (or more precisely their central velocity dispersion), suggests a common formation scenario for galaxies and their central black holes. The growth of bulges and black holes can commonly proceed through external gas accretion or hierarchical mergers, and are both related to starbursts. Internal dynamical processes control and regulate the rate of mass accretion. Self-regulation and feedback are the key of the correlation. It is possible that the growth of one component, e…
Using results from structural analysis of a sample of nearly 1000 local galaxies from the Sloan Digital Sky Survey, we estimate how the mass in central black holes is distributed amongst elliptical galaxies, classical bulges and pseudo-bulges, and investigate the relation between their stellar masses and central stellar velocity dispersion sigma. Assuming a single relation between elliptical galaxy/bulge mass, M_Bulge, and central black hole mass, M_BH, we find that 55^{+8}_{-4} per cent of the mass in black holes in the local universe is in the centres of elliptical galaxies, 41^{+4}_{-2} per…
We consider the problem of growing the largest supermassive black holes from stellar--mass seeds at high redshift. Rapid growth without violating the Eddington limit requires that most mass is gained while the hole has a low spin and thus a low radiative accretion efficiency. If, as was formerly thought, the black--hole spin aligns very rapidly with the accretion flow, even a randomly--oriented sequence of accretion events would all spin up the hole and prevent rapid mass growth. However, using a recent result that the Bardeen--Petterson effect causes {\it counter}alignment of hole and disc sp…
We investigate the physical conditions for the growth of intermediate mass seed black holes assumed to have formed from remnants of the first generation of massive stars. We follow the collapse of high-sigma halos with Tvir > 1e4 K using cosmological, smooth-particle hydrodynamic (SPH) simulations in the standard LCDM model. During collapse of the parent halo the seed holes are incorporated through mergers into larger systems and accrete mass from the surrounding gas. We include a self-consistent treatment of star formation, black hole accretion and associated feedback processes. Even under op…
If supermassive black holes (SMBHs) are the energy sources that power quasars and active galactic nuclei, then QSO SDSS 1148+5251, the quasar with the highest redshift (z_QSO=6.43), hosts a supermassive black hole formed within 0.9 Gyr after the Big Bang. This requirement places constraints on the cosmological formation of SMBHs, believed to grow from smaller initial seeds by a combination of accretion and mergers. We focus on gas accretion onto seeds produced by the collapse of Pop III stars at high redshift. We incorporate the results of recent relativistic, MHD simulations of disk accretion…
Understanding the fate of merging supermassive black holes in galactic mergers, and the gravitational wave emission from this process, are important LISA science goals. To this end, we present results from numerical relativity simulations of binary black hole mergers using the so-called Lazarus approach to model gravitational radiation from these events. In particular, we focus here on some recent calculations of the final spin and recoil velocity of the remnant hole formed at the end of a binary black hole merger process, which may constraint the growth history of massive black holes at the c…
