A Black Hole Mass Determination for the Compact Galaxy Mrk 1216
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2017. The American Astronomical Society. All rights reserved.. Mrk 1216 is a nearby, early-type galaxy with a small effective radius of 2.8 kpc and a large stellar velocity dispersion of 308 km s-1 for its K-band luminosity of . Using integral field spectroscopy assisted by adaptive optics from Gemini North, we measure spatially resolved stellar kinematics within 450 pc of the galaxy nucleus. The galaxy exhibits regular rotation with velocities of 180 km s-1 and a sharply peaked velocity dispersion profile that reaches 425 km s-1 at the center. We fit axisymmetric, orbit-based dynamical models to the combination of these high angular resolution kinematics, large-scale kinematics extending to roughly three effective radii, and Hubble Space Telescope imaging, resulting in a constraint of the mass of the central black hole in Mrk 1216. After exploring several possible sources of systematics that commonly affect stellar-dynamical black hole mass measurements, we find a black hole mass of and an H-band stellar mass-to-light ratio of (1 uncertainties). Mrk 1216 is consistent with the local black hole mass-stellar velocity dispersion relation, but is a factor of 5-10 larger than expectations from the black hole mass-bulge luminosity and black hole mass-bulge mass correlations when conservatively using the galaxy's total luminosity or stellar mass. This behavior is quite similar to the extensively studied compact galaxy NGC 1277. Resembling the quiescent galaxies, Mrk 1216 may be a passively evolved descendant, and perhaps reflects a previous era when galaxies contained over-massive black holes relative to their bulge luminosities/masses, and the growth of host galaxies had yet to catch up.
