Speaker
Description
Primordial black holes (PBHs) in the asteroid-mass range remain a viable and until now unconstrained dark matter (DM) candidate. If
such PBHs exist, they could be captured by stars in DM-dominated environments with low velocity dispersion such as ultra-faint dwarf
galaxies (UFDs). The capture probability increases with the stellar mass, and captured PBHs would rapidly destroy their host stars. As
a result, the presence of PBHs in UFDs would alter their stellar mass functions. Using photometric observations of three ultra-faint
dwarf galaxies from the Hubble Space Telescope, we show that it is unlikely that their mass functions have been significantly modified
by PBHs, and we place constraints on the PBH abundance. In the ultra-faint dwarf galaxy Triangulum II, PBHs around 10^19 g are
excluded at the 2σ (3σ) level from constituting more than ∼ 55% (∼ 78%) of the dark matter, while the possibility that PBHs represent
the entirety of the DM is excluded at the 3.7σ level.
