Journal Article

Black hole mass, host galaxy classification and AGN activity

B. McKernan, K. E. S. Ford and C. S. Reynolds

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 407, issue 4, pages 2399-2410
Published in print October 2010 | ISSN: 0035-8711
Published online July 2010 | e-ISSN: 1365-2966 | DOI:
Black hole mass, host galaxy classification and AGN activity

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We investigate the role of host galaxy classification and black hole mass (MBH) in a heterogeneous sample of 276 mostly nearby (z < 0.1) X-ray and IR-selected active galactic nuclei (AGN). Around 90 per cent of Seyfert 1 AGN in bulge-dominated host galaxies (without disc contamination) span a very narrow range in the observed 12 μm to 2–10 keV luminosity ratio (1 < RIR/X < 7). This narrow dispersion incorporates all possible variations among AGN central engines, including accretion mechanism and efficiency, disc 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 per cent 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 70 Mpc is independent of host galaxy interaction for ∼ Gyr, 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 12 μm luminosity than the median 12 μm luminosity of normal disc- and bulge-dominated galaxies which may represent observational evidence for past epochs of feedback that suppressed 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 14–195 keV 22-month BAT survey of AGN, which is all-sky and unbiased by photoelectric absorption.

Keywords: accretion, accretion discs; galaxies: active; galaxies: nuclei; galaxies: Seyfert; infrared: galaxies; X-rays: galaxies

Journal Article.  10904 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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