A Measurement of the Black-Hole Mass in NGC 1097 using ALMA

TL;DR

This paper estimates the supermassive black hole mass in NGC 1097 using ALMA observations of dense gas kinematics, demonstrating ALMA's effectiveness for such measurements in nearby galaxies.

Contribution

First measurement of SMBH mass in NGC 1097 using dense gas dynamics with ALMA, confirming the method's accuracy and potential for studying galaxy-BH coevolution.

Findings

SMBH mass in NGC 1097 is approximately 1.4 x 10^8 solar masses.

Dense molecular gas kinematics can reliably estimate SMBH masses.

Results align with established SMBH-bulge relationships.

Abstract

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.