A Measurement of the Black-Hole Mass in NGC 1097 using ALMA
  We present an estimate of the mass of the supermassive black hole (SMBH) in
the nearby type-1 Seyfert galaxy \object{NGC 1097} using Atacamma Large
Millimeter/Submillimeter Array (ALMA) observations of dense gas kinematics.
Dense molecular gas dynamics are traced with ${\rm HCN} (J=1-0)$ and ${\rm
HCO^{+}} (J=1-0)$ emission lines. Assuming a host galaxy inclination of
$46^{\circ}$, we derive a SMBH mass, $M_{\rm BH}=1.40^{+0.27}_{-0.32} \times
10^{8}M_{\odot}$, and an I-band mass to light ratio to be
$5.14^{+0.03}_{-0.04}$, using ${\rm HCN} (J=1-0)$. The estimated parameters are
consistent between the two emission lines. The measured SMBH mass is in good
agreement with the SMBH mass and bulge velocity dispersion relationship. Our
result showcases ALMA's potential for deriving accurate SMBH masses, especially
for nearby late-type galaxies. Larger samples and accurate SMBH masses will
further elucidate the relationship between the black hole (BH) and host galaxy
properties and constrain the coevolutionary growth of galaxies and BHs.
