Constraints on primordial black hole dark matter from Galactic center
  X-ray observations
  Surprisingly high masses of the black holes inferred from the LIGO & Virgo
gravitational wave measurements have lead to speculations that the observed
mergers might be due to ${\cal O}(10) M_\odot$ primordial black holes (PBHs).
Furthermore, it has been suggested that the whole amount of dark matter (DM)
might be in that exotic form. We investigate constraints on the PBH DM using
NuSTAR Galactic center (GC) X-ray data. We used a robust Monte Carlo approach
in conjunction with a radiatively inefficient PBH accretion model with commonly
accepted model parameters. Compared to previous studies we allowed for multiple
forms of DM density profiles. Most importantly, our study includes treatment of
the gas turbulence, which significantly modifies the relative velocity between
PBHs and gas. We show that inclusion of the effects of gas turbulence and the
uncertainties related to the DM density profile reduces significantly the gas
accretion onto PBHs compared to the claimed values in previous papers. It is
highly improbable to obtain accreting PBHs brighter than the NuSTAR point
source limit using observationally determined gas velocities. As such, one can
safely conclude that GC X-ray observations cannot rule out ${\cal O}(10)
M_\odot$ PBH DM.
