A 5x10^9 Solar Mass Black Hole in NGC 1277 from Adaptive Optics
  Spectroscopy
  The nearby lenticular galaxy NGC 1277 is thought to host one of the largest
black holes known, however the black hole mass measurement is based on low
spatial resolution spectroscopy. In this paper, we present Gemini Near-infrared
Integral Field Spectrometer observations assisted by adaptive optics. We map
out the galaxy's stellar kinematics within ~440 pc of the nucleus with an
angular resolution that allows us to probe well within the region where the
potential from the black hole dominates. We find that the stellar velocity
dispersion rises dramatically, reaching ~550 km/s at the center. Through
orbit-based, stellar-dynamical models we obtain a black hole mass of (4.9 \pm
1.6) x 10^9 Msun (1-sigma uncertainties). Although the black hole mass
measurement is smaller by a factor of ~3 compared to previous claims based on
large-scale kinematics, NGC 1277 does indeed contain one of the most massive
black holes detected to date, and the black hole mass is an order of magnitude
larger than expectations from the empirical relation between black hole mass
and galaxy luminosity. Given the galaxy's similarities to the higher redshift
(z~2) massive quiescent galaxies, NGC 1277 could be a relic, passively evolving
since that period. A population of local analogs to the higher redshift
quiescent galaxies that also contain over-massive black holes may suggest that
black hole growth precedes that of the host galaxy.
