Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205

Understand

We improve the dynamical black hole (BH) mass estimates in three nearby low-mass early-type galaxies--NGC 205, NGC 5102, and NGC 5206.

• We use new \hst/STIS spectroscopy to fit the star formation histories of the nuclei in these galaxies, and use these measurements to create local color--mass-to-light ratio (\ml) relations.
• We then create new mass models from \hst~imaging and combined with adaptive optics kinematics, we use Jeans dynamical models to constrain their BH masses.
• The masses of the central BHs in NGC 5102 and NGC 5206 are both below one million solar masses and are consistent with our previous estimates, $9.12_{-1.53}^{+1.84}\times10^5$\Msun~and $6.31_{-2.74}^{+1.06}\times10^5$\Msun~(3$\sigma$ errors), respectively.