Related papers: Constraints on Primordial Black Holes from Galacti…
It is broadly accepted that Supermassive Black Holes (SMBHs) are located in the centers of most massive galaxies, although there is still no convincing scenario for the origin of their massive seeds. It has been suggested that primordial…
Formation of significant number of primordial black holes (PBHs) is realized if and only if primordial density fluctuations have a large amplitude, which means that tensor perturbations generated from these scalar perturbations as a second…
We consider primordial black hole (PBH) production in inflationary $\alpha$-attractors. We discuss two classes of models, namely models with a minimal polynomial superpotential as well as modulated chaotic ones that admit PBHs. We find that…
Primordial Black Holes (PBH) may have formed from the collapse of cosmic string loops. The spectral shape of the PBH mass spectrum can be determined by the scaling argument for string networks. Limits on the spectral amplitude derived from…
We study the consequences of supersymmetry for primordial black hole (PBH) abundance constraints. PBHs with mass less than about 10^{11}g will emit supersymmetric particles when they evaporate. In most models of supersymmetry the lightest…
We consider the signatures of a population of primordial black holes (PBHs) in future observations of 21cm radiation from neutral hydrogen at high redshift. We focus on PBHs in the mass range $5 \times 10^{10} kg \lesssim M_{PBH} \lesssim…
Theoretical studies on the memory-burden effect suggest that Primordial Black Holes (PBHs) with masses smaller than $10^{15}$ grams may be viable dark matter candidates and, consequently, be potential sources of high-energy particles in the…
Hawking evaporation of primordial black hole (PBH), with mass $3\times 10^{-17} \lesssim M_{\rm PBH}/M_\odot \lesssim 7\times 10^{-17}$ and fractional abundance $0.01 \lesssim f_{\rm PBH} \lesssim 0.5$, well reproduces 511 keV gamma-ray…
The possibility that a relevant fraction of the dark matter might be comprised of Primordial Black Holes (PBHs) has been seriously reconsidered after LIGO's detection of a $\sim 30 M_{\odot}$ binary black holes merger. Despite the strong…
Overdense regions can collapse into primordial black holes (PBHs) in the early universe, which are a compelling candidate for dark matter. Current constraints leave the asteroid-mass window the only possible one for PBH to account for all…
Primordial black holes (PBHs) within the mass range $10^{17} - 10^{22}$ g are a favorable candidate for describing the all of the dark matter content. Towards the lower end of this mass range, the Hawking temperature, $T_{\rm H}$, of these…
While Primordial Black Holes (PBHs) with masses $M_{\rm PBH} \gtrsim 10^{-11} \, M_\odot$ cannot comprise the entirety of dark matter, the existence of even a small population of these objects can have profound astrophysical consequences. A…
We calculate the gravitational waves (GWs) induced by the density fluctuations due to inhomogeneous distribution of primordial black holes (PBHs) in the case where PBHs eventually dominate and reheat the universe by Hawking evaporation. The…
The abundance of primordial black holes (PBHs) in the mass range $0.1 - 10^3 M_\odot$ can potentially be tested by gravitational wave observations due to the large merger rate of PBH binaries formed in the early universe. To put the…
Black holes formed in the early universe, prior to the formation of stars, can exist as dark matter and also contribute to the black hole merger events observed in gravitational waves. We set a new limit on the abundance of primordial black…
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…
We investigate the effect of non-evaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable…
Ultra-light primordial black holes (PBHs) in the mass range of 10$^{16}$ - 10$^{22}$ g are allowed by current observations to constitute a significant fraction, if not all, of the dark matter in the Universe. In this work, we present limits…
The presence of supermassive black holes (SMBHs, $M_{\bullet}\sim 10^{6-10}~M_{\odot}$) in the first cosmic Gyr ($z\gtrsim 6$) challenges current models of BH formation and evolution. We propose a novel mechanism for the formation of early…
As space expands, the energy density in black holes increases relative to that of radiation, providing us with motivation to consider scenarios in which the early universe contained a significant abundance of such objects. In this study, we…