Related papers: The Abundance of Clustered Primordial Black Holes …
We investigate the spatial clustering properties of primordial black holes (PBHs). With minimal assumptions, we show that PBHs created in the radiation era are highly clustered. Using the peaks theory model of bias, we compute the PBH…
It is argued that the bulk of black holes (BH) in the universe are primordial (PBH). This assertion is strongly supported by the recent astronomical observations, which allow to conclude that supermassive BHs with $M= (10^6 - 10^9) M_\odot$…
Many recent observational and theoretical studies suggest that globular clusters (GCs) host compact object populations large enough to play dominant roles in their overall dynamical evolution. Yet direct detection, particularly of black…
We show that the effect of initial non-Gaussian clustering can significantly enhance the event rate for primordial black hole (PBH) coalescence. The impact of such clustering is studied in a specific scenario of multi-stream inflation.…
There has recently been interest in multi-Solar mass Primordial Black Holes (PBHs) as a dark matter (DM) candidate. There are various microlensing, dynamical and accretion constraints on the abundance of PBHs in this mass range. Taken at…
The formation and abundance of primordial black holes (PBHs) arising from the curvature perturbation $\zeta$ is studied. The non-linear relation between $\zeta$ and the density contrast $\delta$ means that, even when $\zeta$ has an exactly…
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…
The recent discovery of critical phenomena arising in gravitational collapse near the threshold of black hole formation is used to estimate the initial mass function of primordial black holes (PBHs). It is argued that the universal scaling…
In this paper, the merger rate of black holes in a cluster of primordial black holes (PBHs) is investigated. The clusters have characteristics close to those of typical globular star clusters. A cluster that has a wide mass spectrum ranging…
We update the constraints on the fraction of the Universe that may have gone into primordial black holes (PBHs) over the mass range $10^{-5}\text{--}10^{50}$ g. Those smaller than $\sim 10^{15}$ g would have evaporated by now due to Hawking…
Next-generation ground-based gravitational wave (GW) detectors are expected to observe millions of binary black hole mergers, a fraction of which will be strongly lensed by intervening galaxies or clusters, producing multiple images with…
Primordial black holes (PBHs) are considered viable candidates for dark matter and the seeds of supermassive black holes (SMBHs), with their fruitful physical influences providing significant insights into the conditions of the early…
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…
Primordial black holes (PBHs) in the mass range $10^{-16}-10^{-11}~M_\odot$ may constitute all the dark matter. We show that gravitational microlensing of bright x-ray pulsars provide the most robust and immediately implementable…
The recent detection by Advanced LIGO of gravitational waves (GW) from the merging of a binary black hole system sets new limits on the merging rates of massive primordial black holes (PBH) that could be a significant fraction or even the…
Microlensing is one of the most promising tools for discovering stellar-mass black holes (BHs) in the Milky Way because it allows us to probe dark or faint celestial compact objects. While the existence of stellar-mass BHs has been…
Sub-parsec binary massive black holes (BBHs) are long anticipated to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO…
Recently, Subaru Hyper Suprime-Cam (HSC) observations found 12 candidates for microlensing events. These events can be explained by primordial black holes (PBHs) with masses of $10^{-7}$-$10^{-6} M_\odot$ and a fraction of all dark matter…
Primordial Black Holes (PBHs) remain a Dark Matter (DM) candidate of the Standard Model of Particle Physics. Previously, we proposed a new method of constraining the remaining PBH DM mass range using microlensing of stars monitored by…
Cosmological observations, e.g., cosmic microwave background, have precisely measured the spectrum of primordial curvature perturbation on larger scales, but smaller scales are still poorly constrained. Since primordial black holes (PBHs)…