Related papers: Accretion, Primordial Black Holes and Standard Cos…
In theories with a broken discrete symmetry, Hubble sized spherical domain walls may spontaneously nucleate during inflation. These objects are subsequently stretched by the inflationary expansion, resulting in a broad distribution of…
Primordial black holes (PBHs) are thought to have been formed as a result of density fluctuations in the very early Universe. It is suggested that PBHs of mass $\sim 5 \times 10^{14} \mathrm{\ g}$ or less have evaporated through the release…
It is argued that it takes an infinite amount of external time for a freely falling test particle to reach the event horizon of a classical black hole (which happens in finite faller time), and that in this time the black hole would have…
Primordial black holes (PBHs) may have formed through the gravitational collapse of cosmological perturbations that were generated and stretched during the inflationary era, later entering the cosmological horizon during the decelerating…
We consider the formation of horizon-size primordial black holes (PBH's) from pre-existing density fluctuations during cosmic phase transitions. It is pointed out that the formation of PBH's should be particularly efficient during the QCD…
We present a numerical investigation of the gravitational collapse of horizon-size density fluctuations to primordial black holes (PBHs) during the radiation-dominated phase of the Early Universe. The collapse dynamics of three different…
First we have assumed the most general static spherically symmetric black hole metric. The accretion of any general kind of fluid flow around the black hole have been investigated. The accretion of fluid flow around the modified Hayward…
The detection of gravitational waves from mergers of tens of Solar mass black hole binaries has led to a surge in interest in Primordial Black Holes (PBHs) as a dark matter candidate. We aim to provide a (relatively) concise overview of the…
Much attention has been drawn to the recent discoveries by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) of merging intermediate mass black holes. Of particular interest is the possibility that the merger events…
We investigate the effect of gravitational back-reaction on the black hole evaporation process. The standard derivation of Hawking radiation is re-examined and extended by including gravitational interactions between the infalling matter…
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.…
In this paper, we consider the hypothesis that fractions of dark matter could be constituted by primordial black holes (PBHs). To test this possibility, we work out the observational properties of a static black hole embedded in the dark…
Primordial black holes that survive until the present have been considered as a dark matter candidate. In this paper we argue that primordial 2-2-hole remnants provide a more promising and testable option. 2-2-holes arise in quadratic…
Several different approaches to quantum gravity suggest the effective dimension of spacetime reduces from four to two near the Planck scale. In light of such evidence, this letter re-examines the thermodynamics of primordial black holes…
We study the formation of black holes from subhorizon and superhorizon perturbations in a matter dominated universe with 3+1D numerical relativity simulations. We find that there are two primary mechanisms of formation depending on the…
Primordial black holes (PBH), while still constituting a viable dark matter component, are expected to evaporate through Hawking radiation. Assuming the semi-classical approximation holds up to near the Planck scale, PBHs are expected to…
We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi- thermal Hawking radiation. The time reversal of…
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…
Primordial black holes (PBHs) are expected to accrete particle dark matter around them to form ultracompact minihalos (UCMHs), if the PBHs themselves are not most of the dark matter. We show that if most dark matter is a thermal relic, then…
A cosmological model in which primordial black holes (PBHs) are present in the cosmic fluid at some instant t=t_0 is investigated. The time t_0 is naturally identified with the end of the inflationary period. The PBHs are assumed to be…