Past Event

If dark matter is fuzzy, the first stars form in massive pancakes

May 4, 2023
4:35 PM - 5:05 PM
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Pupin 1402

Seminar by Mihir Kulkarni, Toledo

Fuzzy dark matter (FDM) is a proposed modification for the standard cold dark matter (CDM) model motivated by small-scale discrepancies in low-mass galaxies. Composed of ultra-light (mass ∼10−22  eV) axions that have their quantum effects manifest on the astrophysical scales, this is one of a  class of candidates that predicts that the first collapsed objects form in relatively massive dark matter halos. This implies that the formation history of the first stars and galaxies would be very different,  potentially placing strong constraints on such models. I will describe our numerical simulations of the formation of the first stars in an FDM  cosmology, following the collapse in a representative volume all the way down to primordial protostar formation including a primordial non-equilibrium chemical network and cooling for the first time. We find two novel results: first, the large-scale collapse results in a very thin and flat gas "pancake"; second, despite the very different cosmology, this pancake fragments until it forms protostellar objects indistinguishable from those in CDM. Combined, these results indicate that the first generation of stars in this model are also likely to be massive and, because of the sheet morphology, do not self-regulate,  resulting in a massive Pop III starburst. These predictions provide a potential smoking gun signature of FDM and similar dark matter candidates.

Host: Greg Bryan