Limits on Primordial Black Holes from M87
  Primordial black holes in the solar mass range are a possibly significant
component of dark matter. We show how an argument relating the deflection of
light by such black holes in the density spike likely to exist around the M87
supermassive black hole, combined with the high resolution observations of the
EHT collaboration, can lead to a strong limits on the primordial black hole
mass fraction in an astrophysically relevant mass range. The results depend on
the model assumed for the dark matter spike and suggest the interest of further
understanding of such spikes as well as further high resolution observations on
supermassive black holes.
