Non-cold dark matter from primordial black hole evaporation

Abstract We study the parameter space of the effective (with two scalars) models of cosmological inflation and primordial black hole (PBH) formation in the modified (R+ R 2) supergravity. Our models describe double inflation, whose first stage is driven by Starobinsky’s scalaron coming from the R 2 gravity, and whose second stage is driven by another scalar belonging to the supergravity multiplet. The ultra-slow-roll regime between the two stages leads a large peak (enhancement) in the power spectrum of scalar perturbations, which results in efficient PBH formation. Both inflation and PBH formation are generic in our models, while those PBH can account for a significant part or the whole of dark matter. Some of the earlier proposed models in the same class are in tension (over 3σ) with the observed value of the scalar tilt ns , so that we study more general models with more parameters, and investigate the dependence of the cosmological tilts (ns,r) and the scalar power spectrum enhancement upon the parameters. The PBH masses and their density fraction (as part of dark matter) are also calculated. A good agreement (between 2σ and 3σ) with the observed value of ns requires fine tuning of the parameters, and it is only realized in the so-called δ-models. Our models offer the (super)gravitational origin of inflation, PBH and dark matter together, and may be confirmed or falsified by future precision measurements of the cosmic microwave background radiation and PBH-induced gravitational waves.

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Cosmological black holes are not described by the Thakurta metric: LIGO-Virgo bounds on PBHs remain unchanged

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09803-4 ◽

2021 ◽

Vol 81 (11) ◽

Author(s):

Gert Hütsi ◽

Tomi Koivisto ◽

Martti Raidal ◽

Ville Vaskonen ◽

Hardi Veermäe

Keyword(s):

Black Holes ◽

Black Hole ◽

Dark Matter ◽

Compact Object ◽

Compact Objects ◽

Primordial Black Hole ◽

Mass Growth ◽

Black Hole Binaries ◽

Physical Conditions ◽

Accretion Physics

AbstractWe show that the physical conditions which induce the Thakurta metric, recently studied by Bœhm et al. in the context of time-dependent black hole masses, correspond to a single accreting compact object in the entire Universe filled with isotropic non-interacting dust. In such a case, accretion physics is not local but tied to the properties of the whole Universe. We show that radiation, primordial black holes or particle dark matter cannot produce the specific energy flux required for supporting the mass growth of the compact objects described by the Thakurta metric. In particular, this solution does not apply to black hole binaries. We conclude that compact dark matter candidates and their mass growth cannot be described by the Thakurta metric, and thus existing constraints on the primordial black hole abundance from the LIGO-Virgo and the CMB measurements remain valid.

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GAMMA RAY BURSTS AND PARTICLE PHYSICS

Modern Physics Letters A ◽

10.1142/s0217732395003033 ◽

1995 ◽

Vol 10 (38) ◽

pp. 2897-2913

Author(s):

DAVID B. CLINE

Keyword(s):

Black Hole ◽

Particle Physics ◽

Gamma Ray ◽

High Energy ◽

Gamma Ray Bursts ◽

Primordial Black Hole ◽

Black Hole Evaporation ◽

Very High Energy ◽

Fine Time ◽

Made In

We provide a brief review of the current situation concerning gamma ray bursts, with emphasis on the role that particle physics may play in the interesting phenomena. The current understanding of GRB origins allows for a large range of physical processes from primordial black hole evaporation to neutron star and black hole collisions. There does not seem to be a simple standard luminosity function and the burst times range from ms to 1000 s of seconds five orders of magnitude. It is likely that some type of fireball model is needed to explain the GRBs. No counterparts of GRB have been detected. We indicate some ways in which progress can be made in either the study of the fine time structure (~μs) or the detection of very high energy photons (>100 GeV to >100 TeV). We also indicate how a small but unique class of the GRB could come from primordial black hole evaporation.

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