Related papers: Expanding Microscopic Black Holes
Black holes are perhaps the most strange and fascinating objects known to exist in the universe. Our understanding of space and time is pushed to its limits by the extreme conditions found in these objects. They can be used as natural…
It is argued that the qualitative features of black holes, regarded as quantum mechanical objects, depend both on the parameters of the hole and on the microscopic theory in which it is embedded. A thermal description is inadequate for…
In the past decade, much effort was devoted to measure the masses of supermassive black holes in galactic nuclei, to establish the relation between black hole mass and the global/nuclear properties of the host galaxy, and to understand the…
We investigate the idea that ultrahigh energy gamma-rays (E>10 TeV) can be produced when charged particles are accelerated by microscopic black holes. We begin by showing that microscopic black holes may exist as remnants of primordial…
Dark matter overdensities around black holes can be searched for by looking at the characteristic imprint they leave on the gravitational waveform of binary black hole mergers. Current theoretical predictions of the density profile of dark…
The existence of massive black holes was postulated in the sixties, when the first quasars were discovered. In the late nineties their reality was proven beyond doubt, in the Milky way and a handful nearby galaxies. Since then, enormous…
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…
Black holes are among the most intriguing objects in modern physics. Their influence ranges from powering quasars and other active galactic nuclei, to providing key insights into quantum gravity. We review the observational evidence for…
It is shown that an exactly static and spherically symmetric black hole event horizon cannot be embedded in a time-dependent geometry. Forcing it to do so results in a naked null singularity at the would-be horizon. Therefore, since the…
Supermassive black holes are located at the center of most, if not all, massive galaxies. They follow close correlations with global properties of their host galaxies (scaling relations), and are thought to play a crucial role in galaxy…
I outline the theory of accretion onto black holes, and its application to observed phenomena such as X-ray binaries, active galactic nuclei, tidal disruption events, and gamma-ray bursts. The dynamics as well as radiative signatures of…
Macroscopic irreversible processes emerge from fundamental physical laws of reversible character. The source of the local irreversibility seems to be not in the laws themselves but in the initial and boundary conditions of the equations…
The discovery of high redshift quasars represents a challenge to the origin of supermassive black holes. Here, two evolutionary scenarios are considered. The first one concerns massive black holes in the local universe, which in a large…
Supermassive black holes are nowadays believed to reside in most local galaxies. Accretion of gas and black hole mergers play a fundamental role in determining the two parameters defining a black hole: mass and spin. I briefly review here…
Most accreting black holes emit a substantial fraction of their luminosity in hard X-rays/soft $\gamma$-rays of up to $\sim{\rm few}\times100$ keV. The observations suggest that the radiating gas is very hot, $T>10^9$ K, and optically thin.…
If light enough primordial black holes (PBH) account for dark matter, then its density decreases with time as they lose mass via Hawking radiation. We show that this time-dependence of the matter density can be formulated as an equivalent…
Models of Co-Decaying dark matter lead to an early matter dominated epoch -- prior to BBN -- which results in an enhancement of the growth of dark matter substructure. If these primordial structures collapse further they can form primordial…
We investigate models in which a spectrum of black holes with Hawking temperature of order the radiation temperature at the beginning of the radiation dominated era can survive long enough to produce a matter dominated era at the observed…
Black holes are expected to evaporate through the process of Hawking radiation. This process is expected to cause the uncertainty in a black hole's position to grow to $\sim M^2/M_{Pl}^3$ over the course of it's lifetime, even as its…
Possible existence of black holes remnants provides a suitable candidates for dark matter. In this paper we study the possibility of existence for such remnants. We consider quantum gravitational induced corrections of black hole's entropy…