Search of primordial black holes from microlensing observations with HSC and OGLE

We use the microlensing search results of stars in the Andromeda galaxy (M31) and the Galactic bulge, which were done with the Subaru Hyper Suprime-Cam (HSC)and the OGLE experiment, respectively, to constrain primordial black holes(PBHs) that could exist in the Milky Way (and M31) halo regions if PBHs make up dark matter (DM) even by some mass fraction. For the HSC data, we found only one possible microlensing event compared to thousands of events if PBHs make up all DM, which were translated into most stringent upper bound on the abundance of PBHs in the mass range $M$$_{PBH}$ = [10$^{−11}$, 10$^{−6}$]$M$$\odot$. From the public OGLE events, we updated the upper limit on PBHs in $M$$_{PBH}$ = [10$^{−6}$, 10$^{−3}$]$M$$\odot$. We also report a possible implication that the 6 ultra short timescale microlensing events in the OGLE catalog can be explained by Earth-mass PBHs.