Mechanical feedback effects on primordial black hole accretion
  Dark matter may consist, at least partially, of primordial black holes formed
during the radiation-dominated era. The radiation produced by accretion onto
primordial black holes leaves characteristic signatures on the properties of
the medium at high redshift, before and after Hydrogen recombination.
Therefore, reliable modelling of accretion onto these objects is required to
obtain robust constraints on their abundance. We investigate the effect of
mechanical feedback, i.e. the impact of outflows (winds and/or jets) on the
medium, on primordial black hole accretion, and thereby on the associated
radiation. Using analytical and numerical calculations, we study for the first
time whether outflows can reduce the accretion rate of primordial black holes
with masses similar to those detected by the LIGO-Virgo collaboration. Despite
the complexity of the accretion rate evolution, mechanical feedback is able to
significantly reduce the primordial black hole accretion rate, at least by an
order of magnitude, when outflows are aligned with the motion of the compact
object. If the outflow is perpendicular to the direction of motion, the effect
is less important but still non-negligible. Outflows from primordial black
holes, even rather weak ones, can significantly decrease the accretion rate,
effectively weakening abundance constraints on these objects. Our results
motivate further numerical simulations with a more realistic setup, which would
yield more precise quantitative predictions.
