Primordial Black Hole Evaporation and Dark Matter Production: I. Solely Hawking radiation

Abstract

Hawking evaporation of black holes in the early Universe is expected to copiously produce all kinds of particles, regardless of their charges under the Standard Model gauge group. For this reason, any fundamental particle, known or otherwise, could be produced during the black hole lifetime. This certainly includes dark matter (DM) particles. This paper improves upon previous calculations of DM production from primordial black holes (PBH) by consistently including the greybody factors, and by meticulously tracking a system of coupled Boltzmann equations. We show that the initial PBH densities required to produce the observed relic abundance depend strongly on the DM spin, varying in about ∼ 2 orders of magnitude between a spin-2 and a scalar DM in the case of non-rotating PBHs. For Kerr PBHs, we have found that the expected enhancement in the production of bosons reduces the initial fraction needed to explain the measurements. We further consider indirect production of DM by assuming the existence of additional and unstable degrees of freedom emitted by the evaporation, which later decay into the DM. For a minimal setup where there is only one heavy particle, we find that the final relic abundance can be increased by at most a factor of ∼ 4 for a scalar heavy state and a Schwarzschild PBH, or by a factor of ∼ 4.3 for a spin-2 particle in the case of a Kerr PBH.

Non-thermal Origin of Asymmetric Dark Matter from Inflaton and Primordial Black Holes

“…While the PBH evaporation can not create baryon asymmetry directly in our minimal scenario, it can create DM directly, as discussed in different contexts [80,84,93,98,101,[104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119]. However, in asymmetric DM scenario, the final DM abundance is dictated by the dark sector asymmetry which is created only by the out-of-equilibrium decay of RHN where the latter is produced dominantly from PBH evaporation.…”

Gravitational Collapse in the Post-Inflationary Universe

“…This includes any stable particles within the overall spectrum of ultra-high energy physics, whether or not they couple directly to the inflaton. As a consequence, a decaying PBH population creates an alternative mechanism to generate dark matter [57][58][59][60][61][62]. Conversely, massless states could contribute to dark radiation [51,61].…”

Testing Super-Heavy Dark Matter from Primordial Black Holes with Gravitational Waves

“…Ultra-light primordial black holes (PBHs), that is, black holes with mass M BH 10 9 g) [1][2][3] that exist and evaporate prior to Big Bang Nucleosynthesis (BBN) via Hawking radiation [4], can leave their traces by producing Gravitational Waves (GWs) [5][6][7][8][9][10][11][12], generating the Baryon asymmetry of the Universe (BAU) [13][14][15][16][17][18][19][20] and cosmologically stable relics [21,22]. Most importantly, owing to the fact that PBHs must be agnostic about Standard Model (SM) quantum numbers, as they evaporate they must also produce Dark Matter (DM) [13,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40].…”