Ultralight Boson Dark Matter and Event Horizon Telescope Observations of M87^{*}

The initial data from the Event Horizon Telescope (EHT) on M87^{*}, the supermassive black hole at the center of the M87 Galaxy, provide direct observational information on its mass, spin, and accretion disk properties. A combination of the EHT data and other constraints provides evidence that M87^{*} has a mass ∼6.5×10^{9}  M_{⊙}. EHT also inferred the dimensionless spin parameter |a^{*}|≳0.5 from jet properties; a separate recent analysis using only the light from near M87^{*} as measured by the EHT Collaboration found |a^{*}|=0.9±0.1. These determinations disfavor ultralight bosons of mass μ_{b}∈(0.85,4.6)×10^{-21}  eV for spin-one bosons and μ_{b}∈(2.9,4.6)×10^{-21}  eV for spin-zero bosons, within the range considered for fuzzy dark matter, invoked to explain dark matter distribution on approximately kiloparsec scales. Future observations of M87^{*} could be expected to strengthen our conclusions.