# Ultra Light Boson Dark Matter and Event Horizon Telescope Observations of M87*

## TL;DR

This paper discusses how Event Horizon Telescope observations of M87* challenge the existence of ultra light boson dark matter with a specific mass range, providing new constraints on dark matter models.

## Contribution

It combines EHT data with other constraints to disfavor ultra light boson dark matter of a certain mass, offering novel observational limits.

## Key findings

- EHT data constrains M87*'s mass and spin.
- Results disfavor ultra light bosons of mass ~10^{-21} eV.
- Future observations could further test these constraints.

## Abstract

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.