scholarly journals GRAVITATIONAL-WAVE CONSTRAINTS ON ABUNDANCE OF PRIMORDIAL BLACK HOLES

2011 ◽  
Vol 01 ◽  
pp. 126-131
Author(s):  
RYO SAITO ◽  
JUN'ICHI YOKOYAMA
Keyword(s):  
Black Holes ◽  
Mass Range ◽  
Density Fluctuations ◽  
Primordial Black Holes ◽  
Root Mean Square Amplitude ◽  
Order Tensor ◽  
Pulsar Timing ◽  
Future Space ◽  
Timing Data ◽  
Laser Interferometers

Formation of primordial black holes (PBHs) requires a large root-mean-square amplitude of density fluctuations, which generate second-order tensor perturbations that can be compared with observational constraints. We show that pulsar timing data essentially rules out PBHs with 102–4 M⊙ which were previously considered as a candidate of intermediate-mass black hoes and that PBHs with mass range 1020–25 g which provide an astrophysical candidate for dark matter may be probed by future space-based laser interferometers.

scholarly journals Constraints on primordial black holes

2021 ◽  
Vol 84 (11) ◽  
pp. 116902
Author(s):  
Bernard Carr ◽  
Kazunori Kohri ◽  
Yuuiti Sendouda ◽  
Jun’ichi Yokoyama
Keyword(s):  
Black Holes ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Cosmic Ray ◽  
Mass Range ◽  
Big Bang ◽  
Mass Scale ◽  
Density Fluctuations ◽  
Primordial Black Holes ◽  
Small Contribution

Abstract 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 to 1050 g. Those smaller than ∼1015 g would have evaporated by now due to Hawking radiation, so their abundance at formation is constrained by the effects of evaporated particles on big bang nucleosynthesis, the cosmic microwave background (CMB), the Galactic and extragalactic γ-ray and cosmic ray backgrounds and the possible generation of stable Planck mass relics. PBHs larger than ∼1015 g are subject to a variety of constraints associated with gravitational lensing, dynamical effects, influence on large-scale structure, accretion and gravitational waves. We discuss the constraints on both the initial collapse fraction and the current fraction of the dark matter (DM) in PBHs at each mass scale but stress that many of the constraints are associated with observational or theoretical uncertainties. We also consider indirect constraints associated with the amplitude of the primordial density fluctuations, such as second-order tensor perturbations and μ-distortions arising from the effect of acoustic reheating on the CMB, if PBHs are created from the high-σ peaks of nearly Gaussian fluctuations. Finally we discuss how the constraints are modified if the PBHs have an extended mass function, this being relevant if PBHs provide some combination of the DM, the LIGO/Virgo coalescences and the seeds for cosmic structure. Even if PBHs make a small contribution to the DM, they could play an important cosmological role and provide a unique probe of the early Universe.

Primordial black holes and the observable features of the universe

2015 ◽  
Vol 24 (13) ◽  
pp. 1545005 ◽  
Author(s):  
K. M. Belotsky ◽  
A. A. Kirillov ◽  
S. G. Rubin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Galactic Center ◽  
Mass Range ◽  
Primordial Black Holes ◽  
Simultaneous Solution ◽  
Supermassive Black Hole ◽  
Range Distribution ◽  
The Universe

Here, we briefly discuss the possibility to solve simultaneously with primordial black holes (PBHs) the problems of dark matter (DM), reionization of the universe, origin of positron line from Galactic center and supermassive black hole (BH) in it. Discussed scenario can naturally lead to a multiple-peak broad-mass-range distribution of PBHs in mass, which is necessary for simultaneous solution of the problems.

scholarly journals μ-distortion around stupendously large primordial black holes

2021 ◽  
Vol 2021 (11) ◽  
pp. 054
Author(s):  
Heling Deng
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Speed Of Sound ◽  
Mass Range ◽  
Primordial Black Holes ◽  
Black Hole Mass ◽  
Angular Scale ◽  
Λcdm Model ◽  
Homogeneous Background ◽  
Current Bound

Abstract In a variety of mechanisms generating primordial black holes, each black hole is expected to form along with a surrounding underdense region that roughly compensates the black hole mass. This region will propagate outwards and expand as a shell at the speed of sound in the homogeneous background. Dissipation of the shell due to Silk damping could lead to detectable μ-distortion in the CMB spectrum: if black holes are rare on the last scattering surface, the signal(s) would be pointlike; whereas if there are a sufficient number of them, we could have a uniform distortion in the CMB sky. While the current bound on the average μ-distortion is |μ̅| ≲ 10-4, the standard ΛCDM model predicts |μ̅| ∼ 10-8, which could possibly be detected in future missions. It is shown in this work that the non-observation of μ̅ beyond ΛCDM can place a new upper bound on the density of supermassive primordial black holes within the mass range 106 M ☉≲ M ≲ 1015 M ☉. Furthermore, black holes with initial mass M ≳ 1012 M ☉ could leave a pointlike distortion with μ ≳10-8 at an angular scale ∼ 1° in CMB, and its non-observation would impose an even more stringent bound on the population of these stupendously large primordial black holes.

scholarly journals Exploring the early Universe with Gaia and Theia

2021 ◽  
Vol 2021 (12) ◽  
pp. 023
Author(s):  
Juan Garcia-Bellido ◽  
Hitoshi Murayama ◽  
Graham White
Keyword(s):  
Early Universe ◽  
Topological Defects ◽  
Mass Range ◽  
Primordial Black Holes ◽  
Solar Mass ◽  
Pulsar Timing ◽  
Asymmetric Dark Matter ◽  
Early Universe Cosmology ◽  
Gravitational Wave Background ◽  
Shed Light

Abstract It has recently been pointed out that Gaia is capable of detecting a stochastic gravitational wave background in the sensitivity band between the frequency of pulsar timing arrays and LISA. We argue that Gaia and Theia have great potential for early universe cosmology, since such a frequency range is ideal for probing phase transitions in asymmetric dark matter, SIMP and the cosmological QCD transition. Furthermore, there is the potential for detecting primordial black holes in the solar mass range produced during such an early universe transition and distinguish them from those expected from the QCD epoch. Finally, we discuss the potential for Gaia and Theia to probe topological defects and the ability of Gaia to potentially shed light on the recent NANOGrav results.

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 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.

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