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Register a new userDark matter and dark radiation from evaporating Kerr primordial black holes
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Isabella Masina
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The mechanism of the generation of dark matter and dark radiation from the evaporation of primordial black holes is very interesting. We consider the case of Kerr black holes to generalize previous results obtained in the Schwarzschild case. For dark matter, the results do not change dramatically and the bounds on warm dark matter apply similarly: in particular, the Kerr case cannot save the scenario of black hole domination for light dark matter. For dark radiation, the expectations for $Delta N_{eff}$ do not change significantly with respect to the Schwarzschild case, but for an enhancement in the case of spin 2 particles: in the massless case, however, the projected experimental sensitivity would be reached only for extremal black holes.
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The direct detection of sub-GeV dark matter interacting with nucleons is hampered by to the low recoil energies induced by scatterings in the detectors. This experimental difficulty is avoided in the scenario of boosted dark matter where a component of dark matter particles is endowed with large kinetic energies. In this Letter, we point out that the current evaporation of primordial black holes with masses from $10^{14}$ to $10^{16}$ g is a source of boosted light dark matter with energies of tens to hundreds of MeV. Focusing on the XENON1T experiment, we show that these relativistic dark matter particles could give rise to a signal orders of magnitude larger than the present upper bounds. Therefore, we are able to significantly constrain the combined parameter space of primordial black holes and sub-GeV dark matter. In the presence of primordial black holes with a mass of $10^{15}~mathrm{g}$ and an abundance compatible with present bounds, the limits on DM-nucleon cross-section are improved by four orders of magnitude.
Primordial black holes (PBHs) hypothetically generated in the first instants of life of the Universe are potential dark matter (DM) candidates. Focusing on PBHs masses in the range $[5 times10^{14} - 5 times 10^{15}]$g, we point out that the neutrinos emitted by PBHs evaporation can interact through the coherent elastic neutrino nucleus scattering (CE$ u$NS) producing an observable signal in multi-ton DM direct detection experiments. We show that with the high exposures envisaged for the next-generation facilities, it will be possible to set bounds on the fraction of DM composed by PBHs improving the existing neutrino limits obtained with Super-Kamiokande. We also quantify to what extent a signal originating from a small fraction of DM in the form of PBHs would modify the so-called neutrino floor, the well-known barrier towards detection of weakly interacting massive particles (WIMPs) as the dominant DM component.
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Recently, Kallosh and Linde have drawn attention to a new family of superconformal inflationary potentials, subsequently called $alpha$-attractors. The $alpha$-attractor family can interpolate between a large class of inflationary models. It also has an important theoretical underpinning within the framework of supergravity. We demonstrate that the $alpha$-attractors have an even wider appeal since they may describe dark matter and perhaps even dark energy. The dark matter associated with the $alpha$-attractors, which we call $alpha$-dark matter ($alpha$DM), shares many of the attractive features of fuzzy dark matter, with $V(varphi) = frac{1}{2}m^2varphi^2$, while having none of its drawbacks. Like fuzzy dark matter, $alpha$DM can have a large Jeans length which could resolve the cusp-core and substructure problems faced by standard cold dark matter. $alpha$DM also has an appealing tracker property which enables it to converge to the late-time dark matter asymptote, $langle wrangle simeq 0$, from a wide range of initial conditions. It thus avoids the enormous fine-tuning problems faced by the $m^2varphi^2$ potential in describing dark matter.
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