Shining Primordial Black Holes
  We study the well-motivated mixed dark matter (DM) scenario composed of a
dominant thermal WIMP, highlighting the case of $SU(2)_L$ triplet fermion
"winos", with a small fraction of primordial black holes (PBHs). After the wino
kinetic decoupling, the DM particles are captured by PBHs leading to the
presence of PBHs with dark minihalos in the Milky Way today. The strongest
constraints for the wino DM come from the production of narrow line gamma rays
from wino annihilation in the Galactic Center. We analyse in detail the
viability of the mixed wino DM scenario, and determine the constraints on the
fraction of DM in PBHs assuming a cored halo profile in the Milky Way. We show
that already with the sensitivity of current indirect searches, there is a
significant probability for detecting a gamma ray signal characteristic for the
wino annihilation in a single nearby dressed PBH when $M_{\text{PBH}} \sim
M_{\odot}$, which we refer to as a "shining black hole". Similar results should
apply also in more general setups with ultracompact minihalos or other DM
models, since the accretion of DM around large overdensities and DM
annihilation are both quite generic processes.
