Related papers: Black Holes in Accelerated Universe
We report results of a project investigating the growth of super-massive black holes (BHs) by disk accretion. We find that the BH mass growth is quick enough to account for the inferred masses in the highest-redshift quasars, and the growth…
We consider the evolution of primordial black holes formed during the high energy phase of the braneworld scenario. We show that the effect of accretion from the surrounding radiation bath is dominant compared to evaporation for such black…
We investigate the effects of accretion of phantom energy onto primordial black holes. Since Hawking radiation and phantom energy accretion contribute to a {\it decrease} of the mass of the black hole, the primordial black hole that would…
Black holes across a broad range of masses play a key role in the evolution of galaxies. The initial seeds of black holes formed at $z \sim 30$ and grew over cosmic time by gas accretion and mergers. Using observational data for quasars and…
In the classical theory of general relativity black holes can only absorb and not emit particles. When quantum mechanical effects are taken into account, then the black holes emit particles as hot bodies with temperature proportional to…
We examine how cosmological expansion arises in a universe containing a lattice of spinning black holes. We study averaged expansion properties as a function of fundamental properties of the black holes, including the bare mass of the black…
We recently studied the formation and evaporation of primordial black holes in a simple braneworld cosmology, namely Randall-Sundrum Type II. Here we study the effect of accretion from the cosmological background onto the black holes after…
We consider the evolution of primordial black holes in a generalyzed Jordan-Brans-Dicke cosmological model where both the Brans-Dicke scalar field and its coupling to gravity are dynamical functions determined from the evolution equations.…
Recent observations have found a large number of supermassive black holes already in place in the first few hundred million years after Big Bang. The channels of formation and growth of these early, massive black holes are not clear, with…
We use the integrated spectrum of the X-ray background and quasars Spectral Energy Distribution to derive the contribution of quasars to the energy output of the Universe. We find a lower limit for the energy from accretion onto black holes…
We use medium resolution optical spectra of 3CR radio galaxies to estimate their black hole masses and accretion rates. Black hole masses are found from central stellar velocity dispersions and accretion rates are derived from narrow…
The origin of the supermassive black holes that power the most distant quasars observed is largely unknown. One hypothesis is that they grew rapidly from intermediate-mass seeds (~100 M_sun) left by the first stars. However, some previous…
Dark matter overdensities around black holes can alter the dynamical evolution of a companion object orbiting around it, and cause a dephasing of the gravitational waveform. Here, we present a refined calculation of the co-evolution of the…
The discovery of supermassive black holes with masses $\gtrsim 10^9 M_\odot$ at redshifts $z\gtrsim 10$ challenges conventional formation scenarios based on baryonic accretion and mergers within the first few hundred million years. We…
The black hole mass function of supermassive black holes describes the evolution of the distribution of black hole mass. It is one of the primary empirical tools available for mapping the growth of supermassive black holes and for…
We argue that supermassive black hole growth in AGN occurs via sequences of randomly--oriented accretion discs with angular momentum limited by self--gravity. These stably co-- or counter--align with the black hole spin with almost equal…
Based on the numerical solution of the time-dependent relativistic Euler equations onto a fixed Schwarzschild background space-time, we estimate the accretion rate of radial flow toward the horizon of a test perfect fluid obeying an ideal…
We investigate the evolution of supermassive black hole mass (M_BH) and the host spheroid mass (M_sph) in order to track the history of the M_BH-M_sph relationship. The typical mass increase of M_BH is calculated by a continuity equation…
In this paper we investigate a steady accretion within the Einstein-Straus vacuole, in the presence of the cosmological constant. The dark energy damps the mass accretion rate and --- above certain limit --- completely stops the steady…
Black hole spins affect the efficiency of the "classical" accretion processes, hence the radiative output from quasars. Spins also determine how much energy is extractable from the hole itself. Recently it became clear that massive black…