The Host Galaxies of Active Galactic Nuclei with Direct Black Hole Mass Measurements

TL;DR

This study provides precise measurements of black hole masses in active galactic nuclei and analyzes their host galaxy properties, establishing scaling relations that extend to lower mass, spiral galaxies, serving as a local benchmark.

Contribution

It presents the most direct and accurate black hole mass measurements in AGNs and analyzes host galaxy properties using Hubble data, extending scaling relations to lower masses.

Findings

Black hole masses match those of quiescent galaxies.

No correlation between AGN orientation and host galaxy disk.

Provides a local benchmark for black hole-galaxy evolution studies.

Abstract

Reverberation mapping (RM) determines the mass of black holes (BH) in active galactic nuclei (AGNs) by resolving the BH gravitational sphere of influence in the time domain. Recent RM campaigns yielded direct BH masses through dynamical modeling for a sample of 32 objects, spanning a wide range of AGN luminosities and BH masses. In addition, accurate BH masses have been determined by spatially resolving the broad-line region with GRAVITY for a handful of AGNs. Here, we present a detailed analysis of Hubble Space Telescope images using surface-brightness profile fitting with state-of-the-art programs. We derive AGN luminosity and host-galaxy properties, such as radii and luminosities for spheroid, disk, and bar (if present). The spheroid effective radii were used to measure stellar velocity dispersion from integral-field spectroscopy. Since the BH masses of our sample do not depend on any assumption of the virial factor needed in single-epoch spectroscopic mass estimates, we can show that the resulting scaling relations between the mass of the supermassive BHs and their host galaxies match those of quiescent galaxies, naturally extending to lower masses in these (predominantly) spiral galaxies. We find that the inner AGN orientation, as traced by the broad-line region inclination angle, is uncorrelated with the host-galaxy disk. Our sample has the most direct and accurate MBH measurements of any AGN sample and provides a fundamental local benchmark for studies of the evolution of massive black holes and their host galaxies across cosmic time.