scholarly journals Model-independent discovery prospects for primordial black holes at LIGO

2020 ◽  
Author(s):  
Benjamin V Lehmann ◽  
Stefano Profumo ◽  
Jackson Yant
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Mass Function ◽  
New Physics ◽  
Conclusive Evidence ◽  
Primordial Black Holes ◽  
Black Hole Mass ◽  
Merger Event ◽  
Model Independent ◽  
Merger Rate

Abstract Primordial black holes may encode the conditions of the early universe, and may even constitute a significant fraction of cosmological dark matter. Their existence has yet to be established. However, black holes with masses below ∼1M⊙ cannot form as an endpoint of stellar evolution, so the detection of even one such object would be a smoking gun for new physics, and would constitute evidence that at least a fraction of the dark matter consists of primordial black holes. Gravitational wave detectors are capable of making a definitive discovery of this kind by detecting mergers of light black holes. But since the merger rate depends strongly on the shape of the black hole mass function, it is difficult to determine the potential for discovery or constraint as a function of the overall abundance of black holes. Here, we directly maximize and minimize the merger rate to connect observational results to the actual abundance of observable objects. We show that LIGO can discover mergers of light primordial black holes within the next decade even if such black holes constitute only a very small fraction of dark matter. A single merger event involving such an object would (i) provide conclusive evidence of new physics, (ii) establish the nature of some fraction of dark matter, and (iii) probe cosmological history at scales far beyond those observable today.

scholarly journals Primordial black holes from the QCD epoch: linking dark matter, baryogenesis, and anthropic selection

2020 ◽  
Vol 501 (1) ◽  
pp. 1426-1439
Author(s):  
Bernard Carr ◽  
Sebastien Clesse ◽  
Juan García-Bellido
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Selection Effect ◽  
Mass Function ◽  
Baryon Asymmetry ◽  
Primordial Black Holes ◽  
Cosmological Horizon ◽  
Chandrasekhar Limit ◽  
The Universe ◽  
Characteristic Mass

ABSTRACT If primordial black holes (PBHs) formed at the quark-hadron epoch, their mass must be close to the Chandrasekhar limit, this also being the characteristic mass of stars. If they provide the dark matter (DM), the collapse fraction must be of order the cosmological baryon-to-photon ratio ∼10−9, which suggests a scenario in which a baryon asymmetry is produced efficiently in the outgoing shock around each PBH and then propagates to the rest of the Universe. We suggest that the temperature increase in the shock provides the ingredients for hotspot electroweak baryogenesis. This also explains why baryons and DM have comparable densities, the precise ratio depending on the size of the PBH relative to the cosmological horizon at formation. The observed value of the collapse fraction and baryon asymmetry depends on the amplitude of the curvature fluctuations that generate the PBHs and may be explained by an anthropic selection effect associated with the existence of galaxies. We propose a scenario in which the quantum fluctuations of a light stochastic spectator field during inflation generate large curvature fluctuations in some regions, with the stochasticity of this field providing the basis for the required selection. Finally, we identify several observational predictions of our scenario that should be testable within the next few years. In particular, the PBH mass function could extend to sufficiently high masses to explain the black hole coalescences observed by LIGO/Virgo.

scholarly journals Primordial black holes and the origin of the matter–antimatter asymmetry

2019 ◽  
Vol 377 (2161) ◽  
pp. 20190091 ◽  
Author(s):  
Juan García-Bellido
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Cold Dark Matter ◽  
Hot Spot ◽  
Large Mass ◽  
New Physics ◽  
Primordial Black Holes ◽  
Far From Equilibrium ◽  
The Universe

We review here a new scenario of hot spot electroweak baryogenesis where the local energy released in the gravitational collapse to form primordial black holes (PBHs) at the quark-hadron (QCD) epoch drives over-the-barrier sphaleron transitions in a far from equilibrium environment with just the standard model CP violation. Baryons are efficiently produced in relativistic collisions around the black holes and soon redistribute to the rest of the universe, generating the observed matter–antimatter asymmetry well before primordial nucleosynthesis. Therefore, in this scenario there is a common origin of both the dark matter to baryon ratio and the photon to baryon ratio. Moreover, the sudden drop in radiation pressure of relativistic matter at H 0 / W ± / Z 0 decoupling, the QCD transition and e + e − annihilation enhances the probability of PBH formation, inducing a multi-modal broad mass distribution with characteristic peaks at 10 −6 , 1, 30 and 10 6   M ⊙ , rapidly falling at smaller and larger masses, which may explain the LIGO–Virgo black hole mergers as well as the OGLE-GAIA microlensing events, while constituting all of the cold dark matter today. We predict the future detection of binary black hole (BBH) mergers in LIGO with masses between 1 and 5  M ⊙ , as well as above 80  M ⊙ , with very large mass ratios. Next generation gravitational wave and microlensing experiments will be able to test this scenario thoroughly. This article is part of a discussion meeting issue ‘Topological avatars of new physics’.

scholarly journals Dark matter simulations with primordial black holes in the early Universe

2020 ◽  
Vol 499 (4) ◽  
pp. 4854-4862
Author(s):  
Maxim V Tkachev ◽  
Sergey V Pilipenko ◽  
Gustavo Yepes
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dark Matter Halo ◽  
Future Research ◽  
Primordial Black Holes ◽  
Sizeable Fraction ◽  
Merger Rate ◽  
The Stability ◽  
The Universe ◽  
Good Agreement

ABSTRACT Primordial black holes (PBH) with masses of order $10\!-\!30 \, \mathrm{M}_\odot$ have been proposed as a possible explanation of the gravitational waves emission events recently discovered by the Laser Interferometer Gravitational-Wave Observatory (LIGO). If true, then PBHs would constitute a sizeable fraction of the dark matter component in the Universe. Using a series of cosmological N-body simulations that include both dark matter and a variable fraction of PBHs ranging from fPBH = 10−4 to fPBH = 1, we analyse the processes of formation and disruption of gravitationally bound PBH pairs, as well as the merging of both bound and unbound pairs, and estimate the probabilities of such events. We show that they are in good agreement with the constrains to the PBH abundance obtained by the LIGO and other research groups. We find that pair stability, while being a main factor responsible for the merger rate, is significantly affected by the effects of dark matter halo formation and clustering. As a side result, we also evaluate the effects of numerical errors in the stability of bound pairs, which can be useful for future research using this methodology.

scholarly journals NANOGrav Data Hints at Primordial Black Holes as Dark Matter

2021 ◽  
Vol 126 (4) ◽  
Author(s):  
V. De Luca ◽  
G. Franciolini ◽  
A. Riotto
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Primordial Black Holes

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.

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