Ultra Light 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 provide evidence that M87$^*$
has a mass $\sim 6.5 \times 10^9\,M_\odot$ and dimensionless spin parameter
$|a^*|\gtrsim 0.5$. These determinations disfavor ultra light bosons of mass
$\mu_b\sim 10^{-21}$ eV, within the range considered for fuzzy dark matter,
invoked to explain dark matter distribution on $\sim$ kpc scales. Future
observations of M87$^*$ could be expected to strengthen our conclusions.
