The overmassive black hole in NGC 1277: new constraints from molecular
  gas kinematics
  We report the detection of CO(1-0) emission from NGC 1277, a lenticular
galaxy in the Perseus Cluster. NGC 1277 has previously been proposed to host an
overmassive black hole (BH) compared to the galaxy bulge luminosity (mass),
based on stellar-kinematic measurements. The CO(1-0) emission, observed with
the IRAM Plateau de Bure Interferometer (PdBI) using both, a more compact
(2.9-arcsec resolution) and a more extended (1-arcsec resolution)
configuration, is likely to originate from the dust lane encompassing the
galaxy nucleus at a distance of 0.9 arcsec (~320 pc). The double-horned CO(1-0)
profile found at 2.9-arcsec resolution traces $1.5\times 10^8\ M_\odot$ of
molecular gas, likely orbiting in the dust lane at $\sim 550\ \mathrm{km\
s^{-1}}$, which suggests a total enclosed mass of $\sim 2\times 10^{10}\
M_\odot$. At 1-arcsec resolution, the CO(1-0) emission appears spatially
resolved along the dust lane in east-west direction, though at a low
signal-to-noise ratio. In agreement with the previous stellar-kinematic
measurements, the CO(1-0) kinematics is found to be consistent with an $\sim
1.7\times 10^{10}\ M_\odot$ BH for a stellar mass-to-light ratio of
$M/L_V=6.3$, while a less massive BH of $\sim 5\times 10^{9}\ M_\odot$ is
possible when assuming a larger $M/L_V=10$. While the molecular gas reservoir
may be associated with a low level of star formation activity, the extended
2.6-mm continuum emission is likely to originate from a weak AGN, possibly
characterized by an inverted radio-to-millimetre spectral energy distribution.
Literature radio and X-ray data indicate that the BH in NGC 1277 is also
overmassive with respect to the Fundamental Plane of BH activity.
