The Black Hole in the Most Massive Ultracompact Dwarf Galaxy M59-UCD3
  We examine the internal properties of the most massive ultracompact dwarf
galaxy (UCD), M59-UCD3, by combining adaptive optics assisted near-IR integral
field spectroscopy from Gemini/NIFS, and Hubble Space Telescope (HST) imaging.
We use the multi-band HST imaging to create a mass model that suggests and
accounts for the presence of multiple stellar populations and structural
components. We combine these mass models with kinematics measurements from
Gemini/NIFS to find a best-fit stellar mass-to-light ratio ($M/L$) and black
hole (BH) mass using Jeans Anisotropic Models (JAM), axisymmetric Schwarzschild
models, and triaxial Schwarzschild models. The best fit parameters in the JAM
and axisymmetric Schwarzschild models have black holes between 2.5 and 5.9
million solar masses. The triaxial Schwarzschild models point toward a similar
BH mass, but show a minimum $\chi^2$ at a BH mass of $\sim 0$. Models with a BH
in all three techniques provide better fits to the central $V_{rms}$ profiles,
and thus we estimate the BH mass to be $4.2^{+2.1}_{-1.7} \times 10^{6}$
M$_\odot$ (estimated 1$\sigma$ uncertainties). We also present deep radio
imaging of M59-UCD3 and two other UCDs in Virgo with dynamical BH mass
measurements, and compare these to X-ray measurements to check for consistency
with the fundamental plane of BH accretion. We detect faint radio emission in
M59cO, but find only upper limits for M60-UCD1 and M59-UCD3 despite X-ray
detections in both these sources. The BH mass and nuclear light profile of
M59-UCD3 suggests it is the tidally stripped remnant of a $\sim$10$^{9-10}$
M$_\odot$ galaxy.
