New thresholds for primordial black hole formation during the QCD phase transition

Sobrinho, J. L. G.; Augusto, Pedro; Gonçalves, Andreia

doi:10.1093/mnras/stw2138

Cited by 23 publications

(25 citation statements)

References 40 publications

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“…On the other hand, black hole formation in a matter-dominated phase is not yet studied so much. A matter-dominated phase is considered not only after the matter-radiation equality but also in an earlier stage of the Universe, such as the inflaton-oscillating phase after inflation [21][22][23][24] and the epoch of strong phase transition [25][26][27], for which the mass of the formed black holes is given in terms of the cosmological time of the epoch.…”

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confidence: 99%

Spins of primordial black holes formed in the matter-dominated phase of the Universe

et al. 2017

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Angular momentum plays very important roles in the formation of primordial black holes in the matter-dominated phase of the Universe if it lasts sufficiently long. In fact, most collapsing masses are bounced back due to centrifugal force, since angular momentum significantly grows before collapse. For masses with q ≤ q c ≃ 2.4I 1/3 σ 1/3 H , where q is a nondimensional parameter of initial reduced quadrupole moment, σ H is the density fluctuation at horizon entry t = t H , and I is a parameter of the order of unity, angular momentum gives a suppression factor ∼ exp(−0.15I 4/3 σ −2/3 H ) to the production rate. As for masses with q > q c , the suppression factor is even stronger as ∼ exp(−0.0046q 4 /σ 2 H ). We derive the spin distribution of primordial black holes and find that most of the primordial black holes are rapidly rotating near the extreme value a * = 1, where a * is the nondimensional Kerr parameter at their formation. The smaller σ H is, the stronger the tendency towards the extreme rotation. Combining this result with the effect of anisotropy, we numerically and semianalytically estimate the production rate β 0 of primordial black holes. Then we find that β 0 ≃ 1.9 × 10 −6 f q (q c )I 6 σ 2is the fraction of masses whose q is smaller than q c and we assume f q (q c ) is not too small. We argue that matter domination significantly enhances the production of primordial black holes despite the suppression factor. If the end time t end of the matter-dominated phase satisfies t end (0.4Iσ H ) −1 t H , the effect of the finite duration significantly suppresses primordial black hole formation and weakens the tendency towards large spins.

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confidence: 99%

Spins of primordial black holes formed in the matter-dominated phase of the Universe

et al. 2017

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“…Considering a peaked mass spectrum is not arbitrary and can be justified if PBHs are created, for example, because of a phase transition in the early Universe (see, e.g., [18]). As the primordial cosmological power spectrum is now clearly known not to be blue [19] (at least at large scales), the naturally expected density contrast is not high enough to produce PBHs [20] and specific post-inflationary phenomena are generically required (see, e.g., [21]).…”

Section: Peaked Mass Spectrummentioning

confidence: 99%

Fast radio bursts and the stochastic lifetime of black holes in quantum gravity

2018

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Nonperturbative quantum gravity effects might allow a black-to-white hole transition. We revisit this increasingly popular hypothesis by taking into account the fundamentally random nature of the bouncing time. We show that if the primordial mass spectrum of black holes is highly peaked, the expected signal can in fact match the wavelength of the observed fast radio bursts. On the other hand, if the primordial mass spectrum is wide and smooth, clear predictions are suggested and the sensitivity to the shape of the spectrum is studied.

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“…where M Pl = 1.22 × 10 19 GeV is the Planck mass and H I is the Hubble rate at the time of black hole formation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Alternatively, phase transitions in the early universe may have provided the conditions under which substantial quantities of black holes could have formed [21][22][23][24]. Black holes with initial masses below M i < ∼ 5×10 8 grams will disappear through the process of Hawking evaporation prior to Big Bang Nucleosynthesis (BBN), and are thus almost entirely unconstrained by existing observations.…”

Section: Introductionmentioning

confidence: 99%

Dark radiation and superheavy dark matter from black hole domination

Hooper

Krnjaic

McDermott

2019

J. High Energ. Phys.

179

205

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If even a relatively small number of black holes were created in the early universe, they will constitute an increasingly large fraction of the total energy density as space expands. It is thus well-motivated to consider scenarios in which the early universe included an era in which primordial black holes dominated the total energy density. Within this context, we consider Hawking radiation as a mechanism to produce both dark radiation and dark matter. If the early universe included a black hole dominated era, we find that Hawking radiation will produce dark radiation at a level ∆N eff ∼ 0.03 − 0.2 for each light and decoupled species of spin 0, 1/2, or 1. This range is well suited to relax the tension between late and early-time Hubble determinations, and is within the reach of upcoming CMB experiments. The dark matter could also originate as Hawking radiation in a black hole dominated early universe, although such dark matter candidates must be very heavy (mDM > ∼ 10 11 GeV) if they are to avoid exceeding the measured abundance.

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New thresholds for primordial black hole formation during the QCD phase transition

Cited by 23 publications

References 40 publications

Spins of primordial black holes formed in the matter-dominated phase of the Universe

Spins of primordial black holes formed in the matter-dominated phase of the Universe

Fast radio bursts and the stochastic lifetime of black holes in quantum gravity

Dark radiation and superheavy dark matter from black hole domination

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