New Perspectives on Primordial Black Hole Contributions to Dark Matter

 Cold dark matter, including a component of primordial black holes (PBHs),  accumulates  at early epochs in density spikes around growing supermassive black holes. The deflection of light by PBHs in the spike, in combination with the high angular resolution achieved by EHT observations of M87, allows strong limits to be set on the fractional contribution of subsolar mass PBHs to dark matter.