(1/5) I'm excited about a new paper that I've written with @GordanKrnjaic and Sam McDermott. It combines some of my favorite things: black holes, dark matter, and the Hubble tension.
arxiv.org/abs/1905.01301
#blackholes #cosmology #darkmatter #Hubble
(2/5) If even a small number of black holes were created around the time of inflation, their relative abundance would grow as the universe expands, making it quite plausible that the energy density of the early universe was once dominated by black holes.
(3/5) If these black holes were small, they would quickly Hawking evaporate. Unlike most other particle production mechanisms, this generates all kinds of particles, no matter how feebly interacting -- a promising way to generate dark matter and dark radiation.
(4/5) If the early universe included a black hole dominated era, we find that Hawking radiation will produce dark radiation at a level ΔN_eff∼0.03−0.2 for each light and decoupled species. This range coulld relax the tension between late and early-time Hubble determinations.
(5/5) 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 (>10^11 GeV).
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