SO Web-Colloquia: Primordial black holes, gravitational waves and dark matter

More than twenty years ago, we predicted that massive primordial black holes (PBH) would form via the gravitational collapse of radiation and matter associated with high peaks in the spectrum of curvature fluctuations, and that they could constitute all of the dark matter (DM) today. In 2015, we predicted the clustering and broad mass distribution of PBH, which peaks at several Msun, and whose high-mass tails could be responsible for the seeds of all galaxies. Since then, AdvLIGO/Virgo interferometers have detected gravitational waves from at least fifty merger events of very massive and spin-less black hole binaries, and we propose that they are all PBH. We have recently understood that a universal mechanism associated with rapid changes in the number of relativistic species in the early universe could have been responsible for the formation of PBH at specific scales and thus have a very concrete prediction for the mass spectrum of DM-PBH, with broad peaks at 10^{-5}, 2, 80, and 10^6 Msun. In particular, the QCD quark-hadron transition could be responsible for the efficient production of baryons over antibaryons at PBH collapse, thus explaining the presence of baryons today and the relative abundance of DM. We predict that within a few years a less than one solar mass PBH will be detected by AdvLIGO/Virgo, and that an array of GW detectors could be used to determine the mass and spin distribution of PBH dark matter with 10% accuracy. Thus, gravitational wave astronomy could be responsible for a new paradigm shift in the understanding of the nature of dark matter and galaxy formation.

12/01/2021 - 12:30
Dr. Juan García-Bellido
IFT (UAM-CSIC) , Madrid, Spain