S20B0032abst

S20B0032

Primordial black holes (PBHs) are a viable candidate for dark matter if the PBH masses are in the currently unconstrained “sublunar” mass range 10⁻¹⁶−10⁻¹⁰M_⊙. A well-motivated scenario for PBH production from inflation is based on nucleation of vacuum bubbles in the multiverse cosmology. In this case, the PBH mass function extends well beyond the sublunar mass range, resulting in the population of PBHs that simultaneously accounts for all dark matter, explains the PBH candidate event in Subaru HSC data, and contains both heavy black holes as observed by LIGO and very heavy seeds of super-massive black holes. Some PBHs from this extended mass function inevitably fall into the sensitivity range of microlensing observations by HSC, but no other observational facility is capable of detecting them. Thus, HSC is uniquely in the position to discover or rule out PBHs from the multiverse cosmology if the PBHs are numerous enough to account for dark matter. We request 2 min-cadenced r-band observations of Andromeda galaxy (M31) for 5 nights (that are not necessarily continuous). The proposed observations, using the techniques that some of us have already developed in Niikura et al. (Nature Astronomy, 2019), will advance our understanding of PBH dark matter and the early universe.

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