Marek Abramowicz SUPER-EDDINGTON ACCRETION
Abstract: Quasars and other sources (e.g. ULXs) provide a convincing observational evidence for a stable super-Eddington black hole accretion. Theory predicts that strongly super-Eddington accretion flows form thick tori with a pair of narrow funnels along the rotating axis. Black hole relativistic gravity causes the super-Eddington tori to be marginally locked inside their "relativistic Roche lobes" i.e. particular equipotentials that self-cross along the cusp-shaped inner edge of the torus. A small overflow of the Roche lobe regulates accretion rate near the black hole, and the location of the inner edge regulates the efficiency of accretion, which is much smaller than the standard ~10%. Radiation inside the funnels is collimated into narrow, highly super-Eddington beams. Thermal, viscous, and Papaloizou-Pringle modes of thick disks global hydrodynamical oscillations are stabilized by the small (but dynamical) mass accretion loss caused by the Roche lobe overflow. Little is known about MHD instabilities, convection, radiative transfer, radiative instabilities, and a possible role of global outflows and magnetic fields. Almost nothing is known about outer boundary conditions. All these effects may be rather important in determining details of the super-Eddington accretion physics.
David Alexander Accreting super-massive black holes in high-redshift SCUBA galaxies
Abstract: Deep SCUBA surveys have uncovered a large population of ultra-luminous galaxies at z>1. These sources are often assumed to be starburst galaxies, but there is growing evidence that a substantial fraction host an AGN (i.e., an accreting super-massive black hole). I will present the strongest evidence for this viewpoint to date: the combination of ultra-deep X-ray observations and deep optical spectroscopic data. I will address the question "What powers bright SCUBA galaxies?" and show that a non-negligble fraction of SCUBA galaxies show evidence for binary AGN activity (presumably the early stages of black hole coalesence).
Frederick Baganoff Chandra Observations of Sgr A* and Its Galactic Habitat
Abstract: Over the past five years, the Chandra X-ray Observatory has repeatedly observed Sgr A*, the compact radio source and supermassive black hole at the dynamical center of the Milky Way. The total exposure of 650 ks coupled with Chandra's 0.5 arcsecond resolution have produced the most sensitive X-ray image of our Galactic center, allowing us to study the central black hole and its environment in unprecedented detail. Sgr A* is extremely faint in X-rays, radiating about 11 orders of magnitude below the Eddington limit. The properties of this emission will be discussed, along with the emission from surrounding structures. In October 2000, Chandra discovered a rapid, large-amplitude X-ray flare from Sgr A*. This extreme activity was totally unexpected. Chandra and XMM-Newton have since shown that Sgr A* flares in X-rays on a daily basis. NIR flares have been discovered within the last year at about three times the rate of the X-ray flares, raising the question of whether the X-ray and NIR flares are produced by the same or different processes. I will present results from the first simultaneous detection of an X-ray and NIR flare from Sgr A*. At least in this case, the X-rays and NIR photons appear to arise from the same electron population.
Aaron Barth Intermediate-mass black holes in dwarf galaxies
Abstract: Dynamical searches for black holes in galaxy nuclei do not have the sensitivity to find black holes of mass below 10^6 solar masses at distances beyond the Local Group. However, a few nearby dwarf galaxies do show AGN activity indicating that a black hole is present, with likely masses of order 10^5 solar masses. I will review the evidence for intermediate-mass black holes in dwarf galaxies and describe results from a new search for nuclear activity in dwarf galaxies.
Thomas Beckert The Evolution of the Dusty Vail around AGN
Abstract: Based on the 'unified scheme' for AGN we develop a model for a clumpy and dusty torus surrounding the growing supermassive black holes in the center of galaxies. A stationary, axissymetric model for a cloud distribution in a geometrically thick accretion flow is presented. Cloud-cloud collisions lead to accretion in the combined potential of black hole and nuclear star cluster and fuel the central engine. For a given ratio of type 1 and 2 AGN successful obscuration of the BLR and central source requires mass accretion rates above the Eddington limit for the black hole itself. The model will be tested in nearby sources like NGC 1068 with upcoming optical interferometers. The scenario, which includes accretion through the torus, a strong outflow along the symmetry axis, and feeding of the central accretion disk, predicts the evolution of the obscuring material during the growth of todays supermassive black holes.
Mitchell Begelman AGN feedabck
Abstract: Jets and winds are significant channels for energy loss from accreting black holes. These outflows mechanically heat their surroundings, through shocks as well as gentler forms of heating. I will discuss the nature of this feedback and its possible role in regulating black hole growth. Clusters of galaxies, where feedback effects are evident, may serve as laboratories for studying the nature and distribution of mechanical heating by supermassive black holes.
Ralf Bender Supermassive black holes in galaxy centers
Abstract: TBD
Roger Blandford On the evolution of Black Holes and their host galaxies
Abstract: TBD
Thomas Boller Narrow-Line Seyfert 1 Galaxies as AGN in the making
Abstract: Narrow-Line Seyfert 1 Galaxies (NLS1s) are an important class of Seyfert 1 type galaxies and exhibit extreme X-ray, UV- and optical properties. One important aspect with respect to galaxy evolutionary scenarios is that NLS1s may be AGN in the making and as such, may be low redshift analogues of the high redshift quasars. I will address the strong obvervational facts which support that evolutionary scheme.
Bernhard Brandl Spitzer Observations of Massive Black Holes in Infrared Galaxies
Abstract: The Spitzer Space Telescope, NASA's 4th Great Observatory, was launched on 25 August 2003. With its three scientific instruments on board it covers the wavelength range from 3 to 160 microns and is ideally suited to peek into the dust-enshrouded environments of active galactic nuclei. I will give a brief introduction in the capabilities of this new observatory, and then present some recent results -- from local AGN to ultra-luminous galaxies to Cen-A and to quasars at high redshift.
Niel Brandt X-rays from the First Massive Black Holes
Abstract: X-ray studies of high-redshift (z > 4) active galaxies have advanced dramatically over the past few years, largely due to complementary results from Chandra and XMM-Newton. I will review these results and discuss their implications for the first massive black holes and their young host galaxies. In particular, I will focus on constraints on quasar energetics and environments from a systematic Chandra and XMM-Newton study of the highest redshift known quasars, mostly found by the Sloan Digital Sky Survey. I will also present results from the Chandra Deep Field-North and Extended Chandra Deep Field-South surveys which (1) allow study of the X-ray emission properties of moderate-luminosity active galaxies at z > 4, and (2) constrain the number density of high-redshift active galaxies with implications for reionization. Finally, I will describe how these studies are laying crucial observational groundwork for future missions including Constellation-X, XEUS, and Generation-X.
Volker Bromm Formation of the First Supermassive Black Holes
Abstract: I consider the physical conditions under which supermassive black holes could have formed inside the first galaxies. Numerical simulations indicate that metal-free dwarf galaxies, collapsing at z~10, and with H2 formation suppressed, tend to form a binary black hole system that contains a substantial fraction (> 10%) of the total baryonic mass of the host galaxy. These early black holes lead to quasar activity before the epoch of reionization.
Andrea Comastri Heavily obscured accreting black holes
Abstract: Obscured accretion onto supermassive black holes dominates the Universe high energy output recorded in the X-ray background spectrum. The most recent findings emerging from deep and shallow surveys will be reviewed. In particular the role of heavily obscured Compton Thick sources and their contribution to the black hole mass density will be discussed.
Luigi Danese A Physical model for the co-evolution of QSOs and of their Spheroidal Hosts
Abstract: We present a physically motivated model for the early co-evolution of massive spheroids and active nuclei at their centers. Within dark matter halos, forming at the rate predicted by the canonical hierarchical clustering scenario, the gas evolution is controlled by gravity, radiative cooling, and heating by feedback from SN and from the growing active nucleus. SN heating is increasingly effective with decreasing binding energy in slowing down the star formation and in driving gas outflows. The more massive proto-galaxies virializing at early times are thus the sites of the faster star-formation. The correspondingly higher radiation drag fastens the angular momentum loss by the gas, resulting in a larger accretion rate onto the central black-hole. In turn, the kinetic energy carried by outflows driven by active nuclei can unbind the residual gas, thus halting both the star formation and the black-hole growth, in a time again shorter for larger halos. For the most massive galaxies the gas unbinding time is short enough for the bulk of the star-formation to be completed before type Ia SN can substantially increase the Fe abundance of the interstellar medium, thus accounting for the alpha-enhancement seen in the largest E galaxies. The feedback from SN and from the active nucleus also determines the relationship between the black-hole mass and the mass, or the velocity dispersion, of the host galaxy, as well as the black-hole mass function. In both cases the model predictions are in excellent agreement with the observational data. Coupling the model with GRASIL, a code computing in a self-consistent way the chemical and spectrophotometric evolution of galaxies over a very wide wavelength interval, we obtained predictions in excellent agreement with observations for a number of observables which proved to be extremely challenging for all current semi-analytical models, including the sub-mm counts and the corresponding redshift distributions, and the epoch-dependent K-band luminosity function of spheroidal galaxies.
Karsten Danzmann LISA and black hole merging
Abstract: TBD
Tiziana Di Matteo Black holes and galaxy formation
Abstract: In recent years significant evidence has been accumulated that the formation of black holes and their associated activity is intimately linked to formation of their host galaxies and plays a key role in shaping their evolution. I will discuss the application of cosmological hydrodynamic simulations of galaxy formation to study the growth and activity of black holes in galaxies. By studying the interplay between star formation and black hole fuelling, we can identify physical processes that lead to the observed black hole-galaxy bulge correlations, and to the strong evolution of the quasar population. I will discuss the properties and the evolution of black holes in galaxies and what we can expect to learn from new observations.nter the abstract here
Andreas Eckart Simultaneous NIR and X-Ray Observations of Sagittarius A*
Abstract: We report on the first simultaneous near-infrared/X-ray observations of the massive 3--4$\times$10$^6$\solm black hole at the center of the Milky Way using the NACO adaptive optics instrument at the European Southern Observatories Very Large Telescope and the ACIS-I aboard the Chandra X-ray observatory. On one occasion, a fading flare of Sgr~A* with $>$2 times the quiescent flux was detected at the beginning of the NIR observations. This flare was also detected in the X-domain. Our data therefore represent the first simultaneous NIR/X-ray measurement of the quiescent and flaring state of SgrA*. We find that the flaring state can be conveniently explained with a synchrotron self-Compton model involving up-scattered sub-millimeter photons from a compact source component showing bulk relativistic motion. The size of that component is assumed to be of the order of the Schwarzschild radius. With a value of about 1.3 the spectral overall indices of both states are quite comparable. Since the X-ray flux density is extended, the spectral index for the quiescent state is probably only a limit for the compact source Sgr~A*.
Andrew Fabian The X-ray Background and black holes accretion history
Abstract: TBD
Xiaohui Fan The highest redshift Quasars
Abstract: The discovery of luminous quasars at z>6 indicates the existence billion-solar-mass black holes at the end of cosmic dark ages. They provide the best probes of the early growth of supermassive black holes in the universe, the relation between the formation of early galaxies and black holes, and put constraints on the role of quasars and AGNs to the cosmic reionization. About 1000 quasars have been discovered at z>4, including 50 at z>5 and eight at z>6. I will review the recent observational results on surveys and detailed follow-up observations of the highest redshift quasars, including the evolution of luminosity function and clustering the evolution of spectral properties and chemical enrichment history, distribution of black hole masses and contraints on the mass and star-formation of the earliest quasar host galaxies.
William Forman Outbursts from Supermassive Black Holes and Their Impact on the Hot Gas in Elliptical Galaxies
Abstract: We present the results of a study of the interaction between the supermassive black hole in M87 and its surrounding hot gas from a study of Chandra, ROSAT HRI, and XMM-Newton observations. Many X-ray features appear to be a direct result of repetitive AGN outbursts. In particular, we discuss X-ray cavities around the jet and counter jet and rings of enhanced emission at 14 and 17 kpc, probable shock fronts associated with outbursts that began $1-2\times10^7$ years ago. On larger scales, $\sim$50 kpc from the nucleus, depressions in the surface brightness may be remnants of earlier outbursts. For M87, the mean power driving the shock outburst, $2.4\times 10^{43}$~\ergssec, is three times greater than the radiative losses in the cooling core around M87.
In addition we will briefly discuss new Chandra observations of the jet in Cen A and present the results of a Chandra survey of over 100 early type galaxies. We will highlight nuclear outbursts in individual galaxies and show the correlation of nuclear X-ray luminosity with the black hole mass.
Reinhard Genzel The supermassive black hole in our galactic center
Abstract: TBD
Roberto Gilli The spatial clustering of X-ray selected AGN in the Chandra Msec Fields
Abstract: I will present the first measurements of the spatial correlation function of X-ray selected AGN in the 2Msec Chandra Deep Field North (CDFN) and 1Msec Chandra Deep Field South (CDFS). At a median redshift of z~0.8, and on scales of ~ 1-20 comoving Mpc, the AGN clustering amplitude is found to be a factor of ~2 higher in the CDFS than in the CDFN. No significant differences are found between the clustering properties of soft and hard X-ray selected AGN neither in the CDFS nor in the CDFN. Similarly, there are no significant differences in the clustering properties of type 1 and type 2 AGN neither in the CDFS nor in the CDFN. The AGN spatial correlation function will be compared with that measured for X-ray selected galaxies in the CDFN. Also, the AGN clustering observed in the CDFS and CDFN will be compared with that of other X-ray selected AGN in shallower surveys. Finally, the observed variance between the CDFN and CDFS AGN clustering amplitude will be discussed.
Zoltan Haiman The growth of the earliest supermassive black holes and their contribution to reionization
Abstract: Recent data on cosmic microwave background anisotropies(by WMAP) and on the spectra of high-redshift quasars (by the SDSS) together imply that the reionization history of the universe is extended and complex. I will discuss currently available observational constraints, and the extent to which accreting black holes (BHs) can help explain these data. I will show new evidence that the intergalactic medium contains a significant amount of neutral hydrogen at z~6 and is experiencing rapid ionization. However, I will argue that quasars are unlikely to drive the observed evolution of the neutral fraction without over-producing the present-day soft X-ray background. On the other hand, the seeds of the z~6 quasar BHs likely appeared at much earlier epochs (z~20), and produced hard ionizing radiation by accretion. These early BHs are promising candidates to account for the high redshift (z~15) ionization implied by the WMAP data.
Guenther Hasinger When supermassive black holes were growing: clues from deep X-ray surveys
Abstract: TBD
Sebastian Heinz The importance of outflows for black hole growth
Abstract: I will present new constraints on the contribution from jets to the overall radiative output of accreting black holes. Using these limits and the relation between black hole mass, accretion rate, and radio luminosity, one can estimate the mechanical energy input into the interstellar and intergalactic medium by jets, which, in turn, acts as a limit on the accretion rate and thus on black hole growth. Understanding this interaction quantitatively is key to understanding the accretion history of supermassive black holes, and the mechanical power input is the most critical, still missing bit of information.
Scott Hughes How black holes get their kicks: radiation recoil in binary black hole mergers
Abstract: Gravitational waves from the coalescence of binary black holes carry away linear momentum, causing center of mass recoil. This ``radiation rocket'' has important implications for systems with escape speeds of order the recoil velocity. In this talk, I will describe new calculations of the recoil that use high precision black hole perturbation theory to estimate the magnitude of the final recoil velocity. We find that the recoil has a strong dependence on the binary's parameters - particularly mass ratio, spin of the larger hole, and inclination angle - but that velocities of a few hundred km/sec can be achieved fairly easily.
Guinevere Kauffmann Accretion onto Black Holes in the Local Universe: the SDSS View
Abstract:
Co-authors: Tim Heckman, Christy Tremonti, Jarle Brinchmann, Stephane Charlot and Simon White
We have studied the properties of the host galaxies of 22,000 optically-selected Type 2 AGN in the Sloan Digital Sky Survey. We have demonstrated that AGN occur only in massive (> 10^10 M_sol) galaxies and that powerful AGN occur in galaxies that are currently forming stars. In this talk, I will present the results of our most recent analysis. I will demonstrate that the level of present-day accretion onto a black hole is very strongly correlated with the environment of the galaxy. The difference between Seyferts and Liners is determined by their clustering properties. We also use multi-wavelength data to quantify the amount of material that is being accreted by the black holes and compare this to the total star formation that is occurring in the bulges of the AGN hosts in our sample. We show that the relation between these two quantities corresponds to what is expected from the well-known bulge mass/black hole mass correlation. We conclude that even at the present day, black hole growth and bulge growth are continuing hand-in-hand.
Stelios Kazantzidis Reconstructing the Dynamics of Super Massive Black Holes During the Assembly of Galaxies and Galaxy Halos: The View from state-of-the-art N-body/SPH Simulations
Abstract: We present the results of a large set of new N-body/SPH simulations of binary mergers of disk galaxies with mass ratios of 1:1, 2:1, 3:1, and 4:1, using unprecedented resolution. The multi-component galaxy models we adopt comprise a stellar and a gaseous disk, a bulge, and an extended dark matter halo; their structure is based on the currently favored galaxy formation paradigm within cold dark matter models. At the center of each galaxy, a super-massive black hole is also included, whose mass obeys the $M_{\rm BH}-\sigma$ relation between the black hole mass and the velocity dispersion of the host bulge. The orbital configurations of the encounters are chosen according to recent results of high-resolution cosmological simulations and mimic mergers that occur both at high and low redshift. Tidal and hydrodynamical torques acting during the mergers drive considerable amounts of gas toward the center of the galaxies. However, while in the adiabatic runs, shock heating dominates in the final stage and leads to a fairly extended gas distribution in the remnants, in the simulations where radiative cooling is incorporated gas dissipates efficiently and often settles into a rotationally supported disk-like structure. We find that radiative cooling leads to baryonic dominance in the central few kpc of the remnants and that the very massive nuclear disks that form might fuel the central black holes by losing angular momentum through gravitational instability mechanisms. We discuss the implications of our results for crucial issues including the efficiency of the super-massive black hole binary formation following a galaxy merger, the dependence of the pairing process on the internal structure of the galaxies, and the origin and evolution of the $M_{\rm BH}-\sigma$ relation.
Andrew King Outflows, M - sigma, and the supermassive BH environment
Abstract: TBD
Anton Koekemoer Early Spitzer Detections of Extreme X-ray/Optical sources (EXOs):
Abstract: The first Spitzer images from the GOODS survey have revealed detections of all the Extreme X-ray / Optical sources (`EXO's) in the CDF-South. These X-ray sources are completely undetected in our deep optical GOODS HST/ACS imaging, to limits that place them at the extreme end of the Fx/Fopt parameter space, with values about 100 to 1000 times higher than generally found for Active Galactic Nuclei (AGN). We use their Spitzer detections to investigate two possible scenarios for their nature: (1) their hosts could be extremely faint, obscured high-redshift Extremely Red Objects (EROs), at redshifts about 2 - 5, thus higher redshift than previously studied EROs; (2) some of them could lie at redshifts above about 6 - 7, such that their Lyman-alpha emission is completely redshifted into the IR. In either case, these objects serve as a valuable probe of black hole growth and accretion activity in the early universe.
Stefanie Komossa Growing BHs: Observational evidence for stellar tidal disruption events and supermassive BH binaries
Abstract: Three major feeding mechanisms have been studied in the context of black hole growth: accretion, BH-BH mergers, and tidal capture/disruption of stars. While there is ample evidence that accretion is ongoing in active galaxies, observational evidence for the two other processes remained elusive for many years. Given the intense theoretical work on these latter two processes, it is of great interest to see whether such events do occur in nature, how frequent they are, and what are their properties. In this contribution, we will give a review of observational evidence for supermassive binary black holes and stellar tidal disruption events. We will also present new multi-wavelength observations of stellar tidal disruptions, including most recent XMM and Chandra results on the two most dramatic variability events ever recorded among galaxies.
Julian Krolik Black Hole Spin-Up via Accretion
Abstract: In the classical Novikov-Thorne model for relativistic accretion it is assumed that the angular momentum accreted per unit rest-mass is determined solely by test-particle orbital mechanics, and is therefore purely a function of black hole spin. However, when magnetic torques drive accretion, the grounds for this assumption are removed. Results from recent numerical MHD simulations in full general relativity will be reported showing that when the black hole rotates rapidly, electromagnetic couplings dramatically reduce the accreted angular momentum, potentially posing severe limits on the maximum black hole spin that can be achieved by accretion.
Abraham Loeb Birth and Dynamics of Black Holes in Galaxies
Abstract: Recent data indicates that almost all local galaxies possess a supermassive black hole at their center. When gas accretes onto such black holes it heats-up and shines, resulting in the appearance of a bright quasar. The earliest quasars are found to exist only a billion years after the big bang, and the properties of their X-ray and optical luminosity functions can be described in the context of popular models for galaxy formation. I will discuss recent theoretical work on both the nearest and the most distant supermassive black holes in the universe, including the use of quasars as probes of the reionization epoch (through the Lyman-alpha and 21 cm transitions of neutral hydrogen), the emission of gravitational radiation from black hole binaries at high redshifts, the Brownian motion of black holes in galactic centers, the formation of stars near dormant black holes, and the dramatic radiative and hydrodynamic influence that quasars have on their host galaxies and the surrounding intergalactic medium.
Piero Madau Dynamics and Evolution of the Earliest Seed Massive Black Holes
Abstract: TBD
Laura Maraschi Properties of Jets at Different Scales and the Connection to Accretion Disks
Abstract: We summarize new results on the properties of large scale extragalactic jets derived from the completion of a joint Chandra HST survey of 17 sources.In most cases inverse Compton scattering on the CMB(ICCMB) photons is the preferred mechansim to account for the X-ray emission but we also find synchrotron SEDs and in one case a synchrotron SED in the knot closest to the nucleus followed by a knot with ICCMB-like SED. In general the broad band SEDs of different emission regions along the jet show that the radio to X-ray flux ratio increases with increasing distance from the nucleus.
We discuss the implications of the new findings for the understanding of the physical properties of jets at different scales. Finally we reexamine the connection between jets and accretion disks in SMBH in the framework of a unified description of high power extragalactic jets.
Alessandro Marconi Local Supermassive Black Holes, Relics of Active Galactic Nuclei
Abstract: We quantify the importance of mass accretion during AGN phases in the growth of supermassive black holes (BH) by comparing the mass function of black holes in the local universe with that expected from AGN relics, which are black holes grown entirely with mass accretion during AGN phases. The local BH mass function (BHMF) is estimated by applying the well-known correlations between BH mass, bulge luminosity and stellar velocity dispersion to galaxy luminosity and velocity functions. The density of BH's in the local universe is 4.6 (-1.4; +1.9) (h/0.7)^2 10^5 Msun Mpc^-3. The relic BHMF is derived from the continuity equation with the only assumption that AGN activity is due to accretion onto massive BH's and that merging is not important. We find that the relic BHMF at z=0 is generated mainly at z<3. Moreover, the BH growth is anti-hierarchical in the sense that smaller BH's (MBH< 10^7 Msun) grow at lower redshifts (z<1) with respect to more massive one's (z~1-3). Unlike previous work, we find that the BHMF of AGN relics is perfectly consistent with the local BHMF indicating the local BH's were mainly grown during AGN activity. This agreement is obtained while satisfying, at the same time, the constraints imposed from the X-ray background. The comparison with the local BHMF also suggests that the merging process is not important in shaping the relic BHMF, at least at low redshifts (z<3). Our analysis thus suggests the following scenario: local black holes grew during AGN phases in which accreting matter was converted into radiation with efficiencies epsilon = 0.04-0.16 and emitted at a fraction lambda = 0.1-1.7 of the Eddington luminosity. The average total lifetime of these active phases ranges from ~4.5 10^8 yr for MBH< 10^8 Msun to ~1.5 10^8 yr for MBH> 10^9 Msun.
Smita Mathur Black Hole Growth and the Black Hole Mass--Bulge Relations of AGNs
Abstract: We present black hole mass--bulge velocity dispersion relation for a complete sample of 75 soft X-ray selected AGNs. We find that NLS1s lie below the \mbh--\sig\ relation of BLS1s, confirming the Mathur \etal (2001) result. The statistical result is robust and not due to any systematic measurement error. This has important consequences towards our understanding of black hole formation and growth: black holes grow by accretion in well formed bulges, possibly after a major merger. As they grow, they get closer to the \mbh--\sig\ relation for normal galaxies. The accretion is highest in the beginning and dwindles as the time goes by. Our result does not support theories of \mbh--\sig\ relation in which the black hole mass is a constant fraction of the bulge mass/ velocity dispersion {\it at all times} or those in which bulge growth is controlled by AGN feedback.
Nicola Menci BH accretion and of Starbursts Triggered by Interactions in Hierarchical Galaxy Formation
Abstract: We present the results of a semi-analytic model of galaxy formation which includes a physical description of the starbursts and of accretion onto the central massive BHs. Both such processes are connected to the amount of galactic cold gas destabilized during galaxy encounters. As a result, at high $z$ the protogalaxies grow rapidly by hierarchical merging; meanwhile, much fresh gas is imported and destabilized, so the holes are fueled at their full Eddington rates, and the starbursts are effective to build up a large fraction of the star content of massive galaxies. At lower $z$ the merging rate decline, the refueling peters out, as the residual gas is exhausted while the destabilizing encounters dwindle. So our model uniquely produces at $z>3$ a rise, and at $z\lesssim 2.5$ a decline of the bright QSO population as steep as observed; the predicted local $m_{BH}-\sigma$ relation and the luminosity functions of QSOs from $z\approx 5$ to $z\approx 0$ fit the observations. The corresponding history of starbursts is such that the high-$z$ star formation rate, the B-band luminosity functions, and the luminosity and $z$-distribution of galaxies in K-band at $z\lesssim 2$, all match the existing observations concerning the bright galaxy population.
Andrea Merloni The anti-hierarchical growth of supermassive black holes
Abstract: I present a new method to unveil the history of cosmic accretion and the build-up of 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 proceeds in a radiatively efficient way above a certain rate, and in a radiatively inefficient way below, the redshift evolution of the mass and accretion rate functions are calculated self-consistently. The only tunable parameters are the accretion efficiency and the critical ratio of the X-ray to Eddington luminosity at which the transition between accretion modes takes place. For fiducial values of these parameters, I found that half (85%) of the local BH mass density was accumulated at redshift z<1 (z<3), mostly in radiatively efficient episodes of accretion. The evolution of the BH mass function between z=0 and z~3 shows clear signs of an anti-hierarchical behaviour: while the majority of the most massive objects (M > 10^9) were already in place at z~3, lower mass ones mainly grew at progressively lower redshift. Also, the average accretion rate decreases with time. Consequently, sources in the radiatively inefficient regime of accretion only begin to dominate the comoving accretion energy density in the universe at z<1. I discuss the implications of these results for the efficiency of accretion onto SMBH, the quasars lifetimes and duty cycles and the history of AGN feedback in the form of mechanical energy output
David Merritt Interaction of Supermassive black holes with their stellar and dark matter environments
Abstract: Massive black holes dominate the gravitational potential in their vicinity, and this fact suggests that they should induce observable changes in the distribution of luminous and dark matter at the centers of galaxies. I will review the mechanisms by which this takes place, including collisionless and collisional cusp formation, interaction of binary black holes with their surroundings, Brownian motion, and gravitational radiation recoil. There is reasonable agreement between these models and the observed structure of galactic nuclei, although a number of uncertainties remain, most importantly the unknown efficiency of binary black hole coalescence.
Maryam Modjaz Probing the Magnetic Field in the Accretion Disk of NGC 4258
Abstract: NGC 4258 is a low luminosity Seyfert II galaxy in which water maser emission arises in a very thin accretion disk around a supermassive black hole of 4 x 10^7 M_solar. The detected part of the molecular portion of the disk has an outer radius of about 0.3 pc and is nearly edge-on. We present polarimetric observations of some of the systemic and redshifted high-velocity water maser features obtained with the VLA and the GBT at 22 GHz. We did not detect any circular polarization in the spectrum indicative of Zeeman-induced splitting of the maser lines of water vapor. At a distance of about 0.2 pc from the central black hole, along the diameter perpendicular to the line of sight, the toroidal component of the B field is < 90 mG (from highly redshifted maser components) and the radial component along the line of sight is < 30 mG (from systemic features at 470-510 km/s). Assuming equipartition of thermal and magnetic energy, we estimate an upper limit on the mass accretion rate of ~ 10^-3 alpha M_solar/yr (where alpha is the Shakura-Sunyaev viscosity parameter) for a magnetic field purely along the line-of-sight. We delineate the ramifications of our results on current accretion theories; those include standard thin-disk models and advection-dominated accretion flows, which have been used to explain sub-Eddington-luminosity AGNs.
Pierluigi Monaco Feedback from quasars in galaxy formation
Abstract: The main structural, photometrical and chemical properties of elliptical galaxies suggest that most of their stars formed in a quick starburst at high redshift, eventually interrupted by a strong galactic wind. Quasar activity is a plausible trigger for such a wind. However, the mechanism by which gas is accelerated and removed from a very bright galaxy is still unclear. I propose a scenario in which the joint action of photo-evaporation by the quasar and feedback from SNe trigger the wind. In a typical forming spheroid with multi-phase ISM, an equilibrium configuration is reached where most mass is in low-filling factor cold clouds, while shock waves from exploding type II SNe are pressure-confined in the adiabatic phase by a pervasive hot diffuse phase. Photo-evaporation by the quasar causes a quick and significant mass transfer from the cold clouds to the hot diffuse phase, making the latter much denser. SNRs then become radiative, working to collapse the hot phase into cold clouds to get back to the equilibrium configuration. We show that in this case SNRs percolate the volume, creating a giant galaxy-wide super-bubble. Some gas will be compressed to the centre, feeding the black hole and giving rise to nuclear star formation. In this situation radiation pressure from the quasar and new SNe will pump more energy into the super-bubble. Finally, the consequences of this process on the statistical properties of ellipticals and remnant black holes will be outlined.
Mark Morris Infrared and Radio Observations of the Galactic Black Hole and Its Attendant Stars
Abstract: Mark Morris, Andrea Ghez, Jon Mauerhan, Shelley Wright, Jessica Lu & Eric Becklin Division of Astronomy, Department of Physics and Astronomy, UCLA
We report observations of the accretion flow onto the central black hole of our Galaxy in three distinct wavebands: two measured with the Keck Observatory in the infrared at L' (3.8 µm) and at 12 µm, and the third in the radio at 3 mm, measured with the Owens Valley Radio Observatory. The 3.8 µm radiation is variable on short time scales (a factor of two in less than 40 minutes), and appears to vary stochastically rather than undergoing distinct flares as it does in X-rays. At 12 µm, a sensitive observation shows that spatially varying dust emission underlies the region immediately around SgrA*, so only a limit can be set to the emission from a point source. At 3 mm, we observed for 8 successive days, and found variations up to about 30% on time scales of a few hours. This time scale is consistent with the expected intrinsic size of the source at that wavelength, based on reported VLBA observations.
The current state of the determinations of orbital parameters of stars near the central black hole using diffraction-limited observations at the Keck Observatory will also be presented. Simultaneous orbital fits to the proper motion measurements of 8 stars, coupled with radial velocity data at multiple epochs for the best-constrained star, S0-2, provides the most accurate measure yet of the mass of the black hole (4 +/- 0.3 x 10^6 Msuns) as well as its location to within 1.5 mas, and its proper motion with respect to the stars in the central cluster (0.8 +/- 0.7 mas/yr). These data also provide a well-determined distance to the Galactic center. Perspectives and constraints on the possibility that an extended dark mass distribution surrounds the black hole will be presented.
Sergei Nayakshin Condensation, star formation and accretion in quasars and Sgr A*.
Abstract: In light of the recent observations of Sgr A*, we consider two processes that are vital to the evolution of the accretion flow and black hole growth in AGN. First is condensation of hot material that builds a thin accretion disk. Second is star formation in a self-gravitating accretion disk. The latter may be so efficient as to deplete the accretion disk much faster than the black hole could consume the disk, thus starving the black hole. We show however that continuing star formation and condensation result in disks that are able to transfer most of their mass into the black hole. Among other interesting effects connected with star-disk interactions may be the X-ray/NIR flares observed in Sgr A*.
Hagai Netzer Formation and evolution of massive black holes at redshift 1-3
Abstract: Improved methods for measuring black hole (BH) masses have been used to obtain the BH mass distribution and the M-vs-L relationship of luminous AGNs. The derived BH mass evolution is inconsistent with the accepted theory of galaxy evolution and suggests that the two populations evolved differently at redshifts 1-3. New results concerning the metalicity and accretion rate in the most luminous quasars can shade new light on the epoch of black hole formation.
Thibaut Paumard Sgr A West: a parsec-scale reservoir for accretion onto Sgr A*
Abstract: Sgr A*, the supermassive black hole at the centre of the Milkyway, is surrounded by the HII region Sgr A West, which looks in projection like a mini-spiral with three "arms". We have used high spectral resolution spectro-imaging data to analyse the velocity field of this ionized gas in a 1pc wide field, and came to the conclusion that the spiral pattern is only a projection effect. The mini-spiral is indeed made of several clouds of material, containing dust and ionized gas, and tidally stretched by the supermassive black hole. We have been able to derive an estimate of the mass of these clouds, as well as of their dynamical time-scale through a kinematic model of the main "arm". The origin and fate of this material will be discussed, in the perspective of accretion onto Sgr A*.
Sterl Phinney Black hole astrophysics from gravitational waves
Abstract: The Laser Interferometer Space Antenna (LISA) will tell us directly about two important aspects of the history black hole growth which are difficult to measure in other ways: the rate of growth by capture of compact objects from the surrounding stellar clusters, and by merging of comparable mass black holes. We review the status of the astronomical data, astrophysical inputs, and important uncertainties in these processes, and describe how the relevant signals will be found in the LISA data stream, and what information it will encode.
Daniel Proga Accretion of Low Angular Momentum Material onto Black Holes
Abstract: I will present results from our hydrodynamical and magnetohydrodynamical simulations of accretion flows onto black holes. My main focus is to explore the connection between accretion flows and related outflows. I will consider applications of such flows to low luminosity active galactic nuclei and the Galatic center.
Martin Rees The formation and evolution of first black holes
Abstract: TBD
Hans-Walter Rix The M_BH M_Bulge Relation at Earlier Epochs
Abstract: I will report on a number of recent results to estimate, or limit, both M_BH and M_bulge in objects to z~6. The results point to a picture in which black holes grew faster than the surrounding stellar spheroids, i.e. suggest that M_BH/M_bulge was larger in the past.
Sergey Sazonov Radiative feedback from quasars and the growth of supermassive black holes
Abstract: We assess the importance of photoionization plus Compton heating feedback on the growth of supermassive central BHs at the center of bulges and ellipticals, using the average quasar spectrum derived from cosmic background fields supplemented by other pieces of information. We present simple arguments supporting the idea that the establishement of the Mbh-sigma relation could be in fact due to the difference of such feedback on the gaseous component of spheroids of large and small mass
Bernard Schutz Gravitational waves from merging black holes: theory and simulations
Abstract: TBD
Marek Sikora Are Quasar jets matter or Poynting flux dominated?
Abstract: If quasar jets are accelerated by magnetic fields but terminate as matter dominated, where and how does the conversion take place from Poynting to kinetic flux? To address this question, we study constraints which are imposed on jet structure by observations at different spacial scales. In particular, using high energy spectra of blazars, we derive the number flux of electrons and positrons. This flux is consistent with the rate of creation of pairs in the accretion disk corona and, therefore, there is no need for pair production in the jet. However, the momentum of the leptonic flux is too small to power radio lobes and, therefore, the energy flux of quasar jets must be dominated by magnetic fields and/or protons. We demonstrate that available observational data are consistent with a scenario, according to which acceleration of a jet is accomplished within $10^{3-4} R_g$. In this picture, non-thermal flares --- an attribute of the blazar phenomenon --- are produced by strong shocks, formed in the region where the jet inertia is already dominated by protons. The shocks are formed due to collisions between portions of the jet accelerated to different velocities, and the differential acceleration is very likely related to global MHD instabilities.
Volker Springel Black hole formation and feedback in cosmological simulations
Abstract: I will discuss hydrodynamical cosmological simulations of structure formation that self-consistently follow the growth of supermassive galactic black holes due to gas accretion and black hole mergers. We study different parameterizations of AGN feedback and explore, in particular, its impact on galactic star formation and the thermodynamic state of the intragroup and intracluster media.
Yasuo Tanaka Narrow-line Seyfert 1 galaxies: growing black holes with high accretion rate?
Abstract: Narrow-line Seyfert 1 galaxies commonly exhibit similar spectral features to those of black-hole binaries in the high state. Results of the XMM-Newton data of some NLS1 are presented, and the possibility of supercritical accretion is discussed.
Gijs Verdoes-Kleijn ISM dynamics around Black Holes in Nearby Radio Galaxies.
Abstract: We performed a dynamical analysis of the nuclear gas velocity dispersion around black holes in both active and quiescent ellipticals. Differences are found in the turbulent behavior of nuclear gas in ellipticals with and without radio jets. These results impact the black hole mass determinations by means of gas dynamical modeling which commonly assume circular rotation of the gas disks all the way to the nucleus. We also performed a maximum likelihood analysis which constrains the three dimensional structure and relative orientation of stellar host, central dusty fuel reservoir and jet in a sample of radio galaxies. This analysis is general in the sense that both circular and elliptic thick dust disks are explored together with various distribution functions of jet misalignment angles. A strong bimodal radio jet orientation is found as a function of dust orientation and morphology. This has implications for the triggering and duty cycle of black hole activity in nearby ellipticals. The modeling is based on results from HST imaging and spectroscopy.
Authors: Gijs Verdoes Kleijn (ESO), Roeland van der Marel, Stefi Baum Chris O'Dea (STScI), Tim de Zeeuw (Leiden), Jacob Noel-Storr (Columbia)
Chris Willott The host haloes of the most massive black holes at z>6
Abstract: SDSS quasars at redshifts z>6 are powered by black holes with masses greater than a billion solar masses - equivalent to the most massive in the local universe. Do these quasars act as signposts to the first massive structures to have formed? What are the masses of the dark haloes in which the quasars reside? I will discuss recent observations in the optical and sub-millimetre to identify galaxies associated with these distant quasars and hence estimate the properties of their host haloes.
Stuart Wyithe Calibrating the Black-Hole -- Halo Mass Relation from the Clustering of Quasars
Abstract: The relationship between the mass of a black-hole and the circular velocity of its host dark-matter halo is fundamental to the clustering length of quasars. The clustering length observed in the 2dF quasar redshift survey is consistent with the black-hole--halo relation observed in local galaxies, provided that quasars shine near their Eddington luminosity. The slow evolution of the clustering length with redshift inferred in the 2dF quasar redshift survey strongly favors a scenario where the central black-holes comprise a larger fraction of the host galaxy mass at higher redshifts. In a scenario where quasars are triggered by halo mergers, this scaling, in combination with observed number counts imply that quasars have an episodic lifetime that is set by the dynamical time of a galactic disk rather than by the Salpeter time.