Constraining the abundance of primordial black holes with HSC M31 observation

Masahiro Takada

We carried out a dense cadence survey of Andromeda Galaxy (M31) to search for micro-lensing effects on stars in M31 due to primordial black hole (PBH), which is a viable candidate of dark matter. We developed a method of detecting transients based on the image difference technique, that is now fully integrated in the HSC pipeline. We found various kinds of transients such as star flare, contact binary stars, and eclipse of white dwarf star, but haven't been able to find a secure candidate of PBH microlensing. The null detection of PBH microlensing, only with one-night HSC observation, allows us to put most stringent upper bound on the abundance of PBHs with masses of 10^24g.