Seminars and Journal Clubs

A common origin for baryons and dark matter

by Sebastien Clesse

Europe/Brussels
1-3rd floor-E.349 - Seminar room (E.349) (Cyclotron)

1-3rd floor-E.349 - Seminar room (E.349)

Cyclotron

30
Description

The origin of the baryon asymmetry of the Universe (BAU) and the nature of dark matter are two of the most challenging problems in cosmology. I will present a scenario in which the gravitational collapse of large inhomogeneities at the quark-hadron epoch generates both the baryon asymmetry and dark matter in the form of primordial black holes (PBHs). This is due to the sudden drop in radiation pressure during the transition from a quark-gluon plasma to non-relativistic hadrons. The collapse to a PBH is induced by fluctuations of a light spectator scalar field in rare regions and is accompanied by the violent expulsion of surrounding material, which might be regarded as a sort of "primordial supernova" . The acceleration of protons to relativistic speeds provides the ingredients for efficient baryogenesis around the collapsing regions and its subsequent propagation to the rest of the Universe. This scenario naturally explains the observed BAU and why the baryons and dark matter have comparable densities. The predicted PBH mass distribution ranges from sub-solar to several hundred solar masses. This is compatible with current observational constraints and could explain the rate, mass and low spin of the black hole mergers detected by LIGO-Virgo. Future observations will soon be able to test this scenario.

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