Window function dependence of the novel mass function of primordial black holes

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.

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Bounds from primordial black holes with a near critical collapse initial mass function

Physical Review D ◽

10.1103/physrevd.60.103510 ◽

1999 ◽

Vol 60 (10) ◽

Cited By ~ 14

Author(s):

Graham D. Kribs ◽

Adam K. Leibovich ◽

I. Z. Rothstein

Keyword(s):

Black Holes ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Primordial Black Holes

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Model-independent discovery prospects for primordial black holes at LIGO

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3806 ◽

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.

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Testing Primordial Black Holes with multi-band observations of the stochastic gravitational wave background

Journal of Cosmology and Astroparticle Physics ◽

10.1088/1475-7516/2021/12/012 ◽

2021 ◽

Vol 2021 (12) ◽

pp. 012

Author(s):

Matteo Braglia ◽

Juan García-Bellido ◽

Sachiko Kuroyanagi

Keyword(s):

Black Holes ◽

Gravitational Wave ◽

Particle Physics ◽

State Parameter ◽

Mass Function ◽

Late Time ◽

Primordial Black Holes ◽

Scale Invariant ◽

Wide Range ◽

Gravitational Wave Background

Abstract The mass distribution of Primordial Black Holes (PBHs) is affected by drops in the pressure of the early Universe plasma. For example, events in the standard model of particle physics, such as the W ±/Z 0 decoupling, the quark-hadron transition, the muon and pion becoming non-relativistic, and the annihilation of electrons and positrons, cause a suppression in the Equation of State parameter and leave peaks in the PBH mass function around 10-6, 2, 60, and 106 M ☉, respectively, in the case of a nearly scale-invariant primordial power spectrum. The superposition of unresolved mergers of such PBHs results in a stochastic gravitational-wave background (SGWB) that covers a wide range of frequencies and can be tested with future gravitational wave (GW) detectors. In this paper, we discuss how its spectral shape can be used to infer properties about inflation, the thermal history of the Universe, and the dynamics of binary formation in dense halos encoded in their merger rate formula. Although many of these physical effects are degenerate within the sensitivity of a single detector, they can be disentangled by the simultaneous observation of the SGWB at different frequencies, highlighting the importance of multi-frequency observations of GWs to characterize the physics of PBHs from the early to the late time Universe.

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