Related papers: QSO Lifetimes
We present an estimate of the black hole mass function (BHMF) of broad line quasars (BLQSOs) that self-consistently corrects for incompleteness and the statistical uncertainty in the mass estimates, based on a sample of 9886 quasars at 1 <…
Understanding the growth of the supermassive black holes powering luminous quasars, their co-evolution with host galaxies, and impact on the surrounding intergalactic medium depends sensitively on the duration of quasar accretion episodes.…
QSOs from SDSS, 2QZ and 2SLAQ covering an order of magnitude in luminosity at fixed redshift exhibit similar amplitudes of clustering. In addition, QSO clustering evolution at z>0.5 is well fitted by a model that assumes a fixed host halo…
The dependence of the number density of the bright QSOs at different redshifts ($n_{QSO}(z)$) on initial power spectrum is studied. It is assumed that QSO phenomenon is an early short term stage of evolution of massive galaxies with $M\geq…
The observed number counts of quasars may be explained either by long-lived activity within rare massive hosts, or by short-lived activity within smaller, more common hosts. It has been argued that quasar lifetimes may therefore be inferred…
The evolution of QSO clustering is investigated with a new sample of 388 QSOs with 0.3<z<2.2, B<20.5 and M_B<-23. Evidence is found for an increase of the clustering amplitude with increasing redshift. These measurements allow to further…
We constrain the average episodic quasar lifetime (as in steady-state accretion) using two statistics of quasars that are recently turned off (i.e., dimmed by a large factor): 1) the fraction of turned-off quasars in a statistical sample…
We propose a model of quasar lifetimes in which observational quasar lifetimes and an intrinsic lifetime of rapid accretion are strongly distinguished by the physics of obscuration by surrounding gas and dust. Quasars are powered by gas…
The proximity effect (PE) of QSOs is believed to be useful in constraining the QSO lifetime. Observations on the PE so far, however, give apparently contradictory results -- some are consistent with a long QSO lifetime (>~ a few 10^7 yr),…
Proximity zones of high-redshift quasars are unique probes of supermassive black hole formation, but simultaneously explaining proximity zone sizes and black hole masses has proved to be challenging. We study the robustness of some of the…
I investigate whether useful constraints on the evolution of the relationship between galaxy mass and black hole (BH) mass can be obtained from recent measurements of galaxy stellar mass functions and QSO bolometric luminosity functions at…
We review the current status of QSO clustering measurements, particular with respect to their relevance in understanding AGN physics. Measurements based on the 2dF QSO Redshift Survey (2QZ) find a scale length for QSO clustering of…
We present a robust method to derive the duty cycle of QSO activity based on the empirical QSO luminosity function and on the present-day linear relation between the masses of supermassive black holes and those of their spheroidal host…
The formation of the first massive objects in the infant Universe remains impossible to observe directly and yet it sets the stage for the subsequent evolution of galaxies. While some black holes with masses > billion solar masses? have…
The time evolution of black holes involves both the canonical equations of quantum gravity and the statistical mechanics of Hawking radiation, neither of which contains a time variable. In order to introduce the time, we apply the…
Quasars (Quasi Stellar Objects, abbreviated as QSOs) are still nowadays, close to half a century after their discovery, objects which are not completel y understood. In this brief review a description of the pending problems,…
Older and more recent pieces of observational evidence suggest a strong connection between QSOs and galaxies; in particular, the recently discovered correlation between black hole and galactic bulge masses suggests that QSO activity is…
(Abridged) Based on numerical simulations of galaxy mergers that incorporate black hole (BH) growth, we predict the faint end slope of the quasar luminosity function (QLF) and its evolution with redshift. Our simulations have yielded a new…
We study the cross-correlation between quasars and galaxies by embedding models for the formation and evolution of the two populations in cosmological N-body simulations. We adopt the quasar evolution model of Kauffmann & Haehnelt (2000),…
Recent work on red and blue quasi-stellar objects (QSOs) has identified peculiar number distributions as a function of radio loudness that we explore and attempt to explain from the perspective of a picture in which a subset of the…