Diffuse emission from black hole remnants

Kazemian, Sina; Pascual, Mateo; Rovelli, Carlo; Vidotto, Francesca

doi:10.1088/1361-6382/acc232

Cited by 9 publications

(6 citation statements)

References 49 publications

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“…Interestingly, we may also be able to find hints of black hole remnants as dark matter [60], if PBH evaporation leaves Planck mass remnants behind as suggested by some quantum gravity theories [309][310][311][312][313] (see also Refs. [314][315][316][317]). If so, there is a unique initial PBH mass, that is M ∼ 5 × 10 5 g, that can reheat the universe and its remnants be the dark matter, with a sharp prediction for the frequency of induced GWs peaked at 100Hz [60].…”

Section: Discussionmentioning

confidence: 99%

Gravitational wave constraints on the primordial black hole dominated early universe

Domènech

Lin

Sasaki

2021

J. Cosmol. Astropart. Phys.

105

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We calculate the gravitational waves (GWs) induced by the density fluctuations due to the inhomogeneous distribution of primordial black holes (PBHs) in the case where PBHs eventually dominate and reheat the universe by Hawking evaporation. The initial PBH density fluctuations are isocurvature in nature. We find that most of the induced GWs are generated right after evaporation, when the universe transits from the PBH dominated era to the radiation dominated era and the curvature perturbation starts to oscillate wildly. The strongest constraint on the amount of the produced GWs comes from the big bang nucleosynthesis (BBN). We improve previous constraints on the PBH fraction and find that it cannot exceed 10-4. Furthermore, this maximum fraction decreases as the mass increases and reaches 10-12 for MPBH∼ 5×108 g, which is the largest mass allowed by the BBN constraint on the reheating temperature. Considering that PBH may cluster above a given clustering scale, we also derive a lower bound on the scale of clustering. Interestingly, the GW spectrum for MPBH∼ 104 -108 g enters the observational window of LIGO and DECIGO and could be tested in the future. Although we focus on the PBH dominated early universe in this paper, our methodology is applicable to any model with early isocurvature perturbation.

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Section: Discussionmentioning

confidence: 99%

Gravitational wave constraints on the primordial black hole dominated early universe

Domènech

Lin

Sasaki

2021

J. Cosmol. Astropart. Phys.

105

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“…The modeling of dark matter as relic Planckian black holes is as old as the discussion about their stability [1,[34][35][36][37][38]. The formation of Planck mass black holes at the end of the inflationary phase has been recently investigated as resulting from the collisions of high energy particles [35,36].…”

Section: Discussionmentioning

confidence: 99%

Remnant loop quantum black holes

Borges,

Baranov,

Sobrinho

et al. 2024

Class. Quantum Grav.

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Polymer models inspired by Loop Quantum Gravity (LQG) have been used to describe non-singular quantum black holes with spherical symmetry, with the classical singularity replaced by a transition from a black hole to a white hole. A recent model, with a single polymerisation parameter, leads to a symmetric transition with same mass for the black and white phases, and to an asymptotically flat exterior metric. The radius of the transition surface is, however, not fixed, increasing with the mass. Following similar procedures, in a previous paper we have fixed that radius by identifying the minimal area on the transition surface with the area gap of LQG. This allowed to find a dependence of the polymerisation parameter on the black hole mass, with the former increasing as the latter decreases. It also permitted to extend the model to Planck scale black holes, with quantum fluctuations remaining small at the horizon. In the present paper we extend this analysis to charged black holes, showing that the Cauchy horizon lies beyond of the transition surface. We also show the existence of limiting states with zero surface gravity, the lightest one with $Q = 0$ and $m = \sqrt{2}/4$, and the heaviest with $Q = m = \sqrt{2}/2$. Using our solutions to approximate quasi-steady horizons, we show that Hawking evaporation leads asymptotically to these extremal states, leaving remnant black holes of Planck size.

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“…While this is not definitive evidence of remnants as DM, finding a peak at such a precise frequency would give a strong indication of the PBH reheating plus remnants scenario. This could be further probed by additional signatures of high frequency GWs and the effective number of species [49,58,60,61,91,92].…”

Section: Discussionmentioning

confidence: 99%

Gravitational wave hints black hole remnants as dark matter

Domènech

Sasaki

2023

Class. Quantum Grav.

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The end state of Hawking evaporation of a black hole is uncertain. Some candidate quantum gravity theories, such as loop quantum gravity and asymptotic safe gravity, hint towards Planck sized remnants. If so, the Universe might be filled with remnants of tiny primordial black holes, which formed with mass $M<10^9\,{\rm g}$. A unique scenario is the case of $M\sim 5\times10^5\,{\rm g}$, where tiny primordial black holes reheat the universe by Hawking evaporation and their remnants dominate the dark matter. Here, we point out that this scenario leads to a cosmological gravitational wave signal at frequencies $\sim 100{\rm Hz}$. Finding such a particular gravitational wave signature with, e.g., the Einstein Telescope, would suggest black hole remnants as dark matter.

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Diffuse emission from black hole remnants

Cited by 9 publications

References 49 publications

Gravitational wave constraints on the primordial black hole dominated early universe

Gravitational wave constraints on the primordial black hole dominated early universe

Remnant loop quantum black holes

Gravitational wave hints black hole remnants as dark matter

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