Black Hole Mass, Host galaxy classification and AGN activity

TL;DR

This study examines how host galaxy type and black hole mass influence AGN properties, revealing tight IR/X-ray luminosity ratios, correlations with black hole mass, and insights into galaxy interactions and feedback effects.

Contribution

It provides new constraints on AGN emission models, demonstrates the independence of AGN luminosity from galaxy interactions over Gyr timescales, and suggests ULXs as X-ray sources in LINERs.

Findings

Narrow IR/X-ray luminosity ratio in Seyfert 1 AGN constrains emission models.

AGN luminosity correlates with black hole mass with high confidence.

AGN activity in host galaxies is independent of tidal interactions over Gyr timescales.

Abstract

We investigate the role of host galaxy classification and black hole mass in a heterogeneous sample of 276 mostly nearby (z<0.1) X-ray and IR selected AGN. Around 90% of Seyfert 1 AGN in bulge-dominated host galaxies (without disk contamination) span a very narrow range in the observed 12um to 2-10keV luminosity ratio (1<R_{IR/X}<7). This narrow dispersion incorporates all possible variations among AGN central engines, including accretion mechanism and efficiency, disk opening angle, orientation to sightline, covering fraction of absorbing material, patchiness of X-ray corona and measured variability. As a result, all models of X-ray and IR production in AGN are very strongly constrained. Among Seyfert 1 AGN, median X-ray and IR luminosities increase with black hole mass at >99% confidence. Using ring morphology of the host galaxy as a proxy for lack of tidal interaction, we find that AGN luminosity in host galaxies within 70Mpc is independent of host galaxy interaction for $\sim$ Gyrs, suggesting that the timescale of AGN activity due to secular evolution is much shorter than that due to tidal interactions. We find that LINER hosts have lower 12um luminosity than the median 12um luminosity of normal disk- and bulge-dominated galaxies which may represent observational evidence for past epochs of feedback that supressed star formation in LINER host galaxies. We propose that nuclear ULXs may account for the X-ray emission from LINER 2s without flat-spectrum, compact radio cores. We confirmed the robustness of our results in X-rays by comparing them with the 14-195keV 22-month BAT survey of AGN, which is all-sky and unbiased by photoelectric absorption.