WISDOM Project - I: Black Hole Mass Measurement Using Molecular Gas
  Kinematics in NGC 3665
  As a part of the mm-Wave Interferometric Survey of Dark Object Masses
(WISDOM) project, we present an estimate of the mass of the supermassive black
hole (SMBH) in the nearby fast-rotator early-type galaxy NGC 3665. We obtained
Combined Array for Research in Millimeter Astronomy (CARMA) B and C array
observations of the $^{12}$CO$(J=2-1)$ emission line with a combined angular
resolution of $0".59$. We analysed and modelled the three-dimensional molecular
gas kinematics, obtaining a best-fit SMBH mass $M_{\rm BH}=5.75^{+1.49}_{-1.18}
\times 10^{8}$ $M_{\odot}$, a mass-to-light ratio at $H$-band
$(M/L)_{H}=1.45\pm0.04$ $(M/L)_{\odot, H}$, and other parameters describing the
geometry of the molecular gas disc (statistical errors, all at $3\sigma$
confidence). We estimate the systematic uncertainties on the stellar $M/L$ to
be $\approx0.2$ $(M/L)_{\odot, H}$, and on the SMBH mass to be
$\approx0.4\times10^{8}$ $M_{\odot}$. The measured SMBH mass is consistent with
that estimated from the latest correlations with galaxy properties. Following
our older works, we also analysed and modelled the kinematics using only the
major-axis position-velocity diagram, and conclude that the two methods are
consistent.
