scholarly journals Merger rates in primordial black hole clusters without initial binaries

2020 ◽  
Vol 496 (1) ◽  
pp. 994-1000 ◽  
Author(s):  
Valeriya Korol ◽  
Ilya Mandel ◽  
M Coleman Miller ◽  
Ross P Church ◽  
Melvyn B Davies
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Matter Content ◽  
Density Fluctuations ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Order Of Magnitude ◽  
Three Body ◽  
Small Clusters ◽  
The Universe

ABSTRACT Primordial black holes formed through the collapse of cosmological density fluctuations have been hypothesized as contributors to the dark matter content of the Universe. At the same time, their mergers could contribute to the recently observed population of gravitational-wave sources. We investigate the scenario in which primordial black holes form binaries at late times in the Universe. Specifically, we re-examine the mergers of primordial black holes in small clusters of ∼30 objects in the absence of initial binaries. Binaries form dynamically through Newtonian gravitational interactions. These binaries act as heat sources for the cluster, increasing the cluster’s velocity dispersion, which inhibits direct mergers through gravitational-wave two-body captures. Meanwhile, three-body encounters of tight binaries are too rare to tighten binaries sufficiently to allow them to merge through gravitational-wave emission. We conclude that in the absence of initial binaries, merger rates of primordial black holes in the considered scenario are at least an order of magnitude lower than previously suggested, which makes gravitational-wave detections of such sources improbable.

scholarly journals EVOLUTION OF PRIMORDIAL BLACK HOLE MASS SPECTRUM IN BRANS–DICKE THEORY

2013 ◽  
Vol 22 (05) ◽  
pp. 1350022 ◽  
Author(s):  
D. DWIVEDEE ◽  
B. NAYAK ◽  
L. P. SINGH
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Energy Density ◽  
Analytic Solutions ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Black Hole Mass ◽  
Linear And Nonlinear ◽  
The Universe

We investigate the evolution of primordial black hole mass spectrum by including both accretion of radiation and Hawking evaporation within Brans–Dicke (BD) cosmology in radiation-, matter- and vacuum-dominated eras. We also consider the effect of evaporation of primordial black holes on the expansion dynamics of the universe. The analytic solutions describing the energy density of the black holes in equilibrium with radiation are presented. We demonstrate that these solutions act as attractors for the system ensuring stability for both linear and nonlinear situations. We show, however, that inclusion of accretion of radiation delays the onset of this equilibrium in all radiation-, matter- and vacuum-dominated eras.

scholarly journals Stellar mass primordial black holes as cold dark matter

2020 ◽  
Vol 496 (1) ◽  
pp. 60-66
Author(s):  
J L G Sobrinho ◽  
P Augusto
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Dark Matter ◽  
Mass Spectrum ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Density Fluctuations ◽  
Primordial Black Holes ◽  
Qcd Phase Transition ◽  
The Universe

ABSTRACT Primordial black holes (PBHs) might have formed in the early Universe due to the collapse of density fluctuations. PBHs may act as the sources for some of the gravitational waves recently observed. We explored the formation scenarios of PBHs of stellar mass, taking into account the possible influence of the QCD phase transition, for which we considered three different models: crossover model, bag model, and lattice fit model. For the fluctuations, we considered a running-tilt power-law spectrum; when these cross the ∼10−9–10−1 s Universe horizon they originate 0.05–500 M⊙ PBHs that could (i) provide a population of stellar mass PBHs similar to the ones present on the binaries associated with all-known gravitational wave sources and (ii) constitute a broad-mass spectrum accounting for ${\sim}76{{\ \rm per\ cent}}$ of all cold dark matter in the Universe.

scholarly journals Were recently reported MHz events planet mass primordial black hole mergers?

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Guillem Domènech
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
High Frequency ◽  
Short Note ◽  
Oort Cloud ◽  
Bulk Acoustic Wave ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Wave Antenna ◽  
High Frequency Waves

AbstractA bulk acoustic wave cavity as high frequency gravitational wave antenna has recently detected two rare events at 5.5MHz. Assuming that the detected events are due to gravitational waves, their characteristic strain amplitude lies at about $$h_c\approx 2.5 \times 10^{-16}$$ h c ≈ 2.5 × 10 - 16 . While a cosmological signal is out of the picture due to the large energy carried by the high frequency waves, the signal could be due to the merging of two planet mass primordial black holes ($$\approx 4\times 10^{-4} M_\odot $$ ≈ 4 × 10 - 4 M ⊙ ) inside the Oort cloud at roughly 0.025 pc (5300 AU) away. In this short note, we show that the probability of one such event to occur within this volume per year is around $$1:10^{24}$$ 1 : 10 24 , if such Saturn-like mass primordial black holes are $$1\%$$ 1 % of the dark matter. Thus, the detected signal is very unlikely to be due the merger of planet mass primordial black holes. Nevertheless, the stochastic background of saturn mass primordial black holes binaries might be seen by next generation gravitational wave detectors, such as DECIGO and BBO.

scholarly journals TIME EVOLUTION OF A NONSINGULAR PRIMORDIAL BLACK HOLE

2012 ◽  
Vol 21 (03) ◽  
pp. 1250027
Author(s):  
MANASSE R. MBONYE ◽  
NICHOLAS BATTISTA ◽  
BENJAMIN FARR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Time Evolution ◽  
Evolutionary History ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
History Of ◽  
Early Radiation ◽  
The One ◽  
The Universe

There is growing notion that black holes may not contain curvature singularities (and that indeed nature in general may abhor such spacetime defects). This notion could have implications on our understanding of the evolution of primordial Black holes (PBHs) and possibly on their contribution to cosmic energy. This paper discusses the evolution of a nonsingular black hole (NSBH) based on a recent model [M. R. Mbonye and D. Kazanas, Phys. Rev. D. 72 (2005) 024016]. The model is used to discuss the time evolution of a primordial black hole (PBH), through the early radiation era of the universe to present, under the assumption that PBHs are nonsingular. In particular, we track the evolution of two benchmark PBHs, namely the one radiating up to the end of the cosmic radiation domination era, and the one stopping to radiate currently, and in each case determine some useful features including the initial mass mf and the corresponding time of formation tf. It is found that along the evolutionary history of the universe the distribution of PBH remnant masses (PBH-RM) PBH-RMs follows a power law. We believe such a result can be a useful step in a study to establish current abundance of PBH-MRs.

scholarly journals The minimum testable abundance of primordial black holes at future gravitational-wave detectors

2021 ◽  
Vol 2021 (11) ◽  
pp. 039
Author(s):  
Valerio De Luca ◽  
Gabriele Franciolini ◽  
Paolo Pani ◽  
Antonio Riotto
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Gravitational Wave ◽  
Primordial Black Hole ◽  
Spatial Distributions ◽  
Primordial Black Holes ◽  
Next Generation ◽  
Einstein Telescope ◽  
Gravitational Wave Detectors

Abstract The next generation of gravitational-wave experiments, such as Einstein Telescope, Cosmic Explorer and LISA, will test the primordial black hole scenario. We provide a forecast for the minimum testable value of the abundance of primordial black holes as a function of their masses for both the unclustered and clustered spatial distributions at formation. In particular, we show that these instruments may test abundances, relative to the dark matter, as low as 10-10.

scholarly journals Testing stochastic gravitational wave signals from primordial black holes with optical telescopes

2021 ◽  
Vol 814 ◽  
pp. 136097
Author(s):  
Sunao Sugiyama ◽  
Volodymyr Takhistov ◽  
Edoardo Vitagliano ◽  
Alexander Kusenko ◽  
Misao Sasaki ◽  
...  
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Primordial Black Holes ◽  
Optical Telescopes

scholarly journals A constraint on light primordial black holes from the interstellar medium temperature

2021 ◽  
Author(s):  
Hyungjin Kim
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dwarf Galaxy ◽  
Dark Matter Candidate ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Substantial Fraction ◽  
Interstellar Gas ◽  
Medium Temperature ◽  
Fast Electrons

Abstract Primordial black holes are a viable dark matter candidate. They decay via Hawking evaporation. Energetic particles from the Hawking radiation interact with interstellar gas, depositing their energy as heat and ionization. For a sufficiently high Hawking temperature, fast electrons produced by black holes deposit a substantial fraction of energy as heat through the Coulomb interaction. Using the dwarf galaxy Leo T, we place an upper bound on the fraction of primordial black hole dark matter. For M < 5 × 10−17M⊙, our bound is competitive with or stronger than other bounds.

scholarly journals The Merger Rate of Black Holes in a Primordial Black Hole Cluster

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 372-378
Author(s):  
Viktor D. Stasenko ◽  
Alexander A. Kirillov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Star Clusters ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Central Black Hole ◽  
Solar Mass ◽  
Merger Rate

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 from 10−2 to 10M⊙ (Solar mass) and contains a massive central black hole of the mass M•=103M⊙ is considered. It is shown that in the process of the evolution of cluster, the merger rate changed significantly, and by now, the PBH clusters have passed the stage of active merging of the black holes inside them.

PRIMORDIAL BLACK HOLE PAIR CREATION IN R2 THEORY

1998 ◽  
Vol 13 (28) ◽  
pp. 2289-2293 ◽  
Author(s):  
B. C. PAUL ◽  
S. MUKHERJEE ◽  
G. P. SINGH ◽  
A. BEESHAM
Keyword(s):  
Black Holes ◽  
Semiclassical Approximation ◽  
Pair Creation ◽  
Quadratic Term ◽  
Inflationary Universe ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
De Sitter ◽  
Gravitational Action ◽  
Spatial Section

The probability for quantum creation of an inflationary universe with a pair of black holes has been studied in semiclassical approximation with Hartle–Hawking boundary conditions, assuming a gravitational action which includes a quadratic term in the scalar curvature αR2, α being a constant. The action of the instanton responsible for creating such a universe, with a spatial section with S1×S2 topology, is seen to be less than that of a de Sitter S3 instanton, unless α<-1/(8Λ), where Λ is the cosmological constant. Since negative α implies a classical instability, the probability for production of primordial black holes seems to be suppressd in R2-theory.

On Primordial Black Holes and secondary gravitational waves generated from inflation with solo/multi-bumpy potential

2021 ◽  
Author(s):  
Rui feng Zheng ◽  
Jia ming Shi ◽  
Taotao Qiu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Waves ◽  
Power Spectra ◽  
Small Scale ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Slow Roll ◽  
Spherical Collapse ◽  
Scalar Perturbations

Abstract It is well known that primordial black hole (PBH) can be generated in inflation process of the early universe, especially when the inflaton field has some non-trivial features that could break the slow-roll condition. In this paper, we investigate a toy model of inflation with bumpy potential, which has one or several bumps. We found that potential with multi-bump can give rise to power spectra with multi peaks in small-scale region, which can in turn predict the generation of primordial black holes in various mass ranges. We also consider the two possibilities of PBH formation by spherical collapse and elliptical collapse. And discusses the scalar-induced gravitational waves (SIGWs) generated by the second-order scalar perturbations.

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