The Megamaser Cosmology Project.IX. Black hole masses for three maser galaxies

TL;DR

This study uses VLBI observations of water masers in five galaxies to estimate supermassive black hole masses, confirming known relations and exploring correlations with galaxy luminosities.

Contribution

It provides new SMBH mass estimates for three galaxies and expands the sample of VLBI-confirmed disk maser galaxies, analyzing their properties and correlations.

Findings

Black hole masses estimated for three galaxies.

Confirmed the relation between disk outer radius and SMBH mass.

Identified a tentative correlation between maser disk size and WISE luminosity.

Abstract

As part of the Megamaser Cosmology Project (MCP), we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2.9 $\pm$ 0.3) $\times~10^{6}M_\odot$ for J0437+2456, (1.7 $\pm$ 0.1) $\times~10^{7}M_\odot$ for ESO 558$-$G009, and (1.1 $\pm$ 0.2) $\times~10^{7}M_\odot$ for NGC 5495. In the other two galaxies, Mrk 1029 and NGC 1320, the geometry and dynamics are more complicated and preclude robust black hole mass estimates. Including our new results, we compiled a list of 15 VLBI-confirmed disk maser galaxies with robust SMBH mass measurements. With this sample, we confirm the empirical relation of $R_{out} \propto 0.3 M_{SMBH}$ reported in Wardle & Yusef-Zadeh (2012). We also find a tentative correlation between maser disk outer radii and WISE luminosity. We find no correlations of maser disk size with X-ray 2-10 keV luminosity or [O III] luminosity.