Active galactic nucleus host galaxy morphologies in cosmos

Gabor, J. M. and Impey, C. D. and Jahnke, K. and Simmons, B. D. and Trump, J. R. and Koekemoer, A. M. and Brusa, M. and Cappelluti, N. and Schinnerer, E. and Smolčić, V. and Salvato, M. and Rhodes, J. D. and Mobasher, B. and Capak, P. and Massey, R. and Leauthaud, A. and Scoville, N. (2009) Active galactic nucleus host galaxy morphologies in cosmos. The Astrophysical Journal, 691 (1). pp. 705-722. ISSN 0004-637X

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We use Hubble Space Telescope/Advanced Camera for Surveys images and a photometric catalog of the Cosmic Evolution Survey (COSMOS) field to analyze morphologies of the host galaxies of ~400 active galactic nucleus (AGN) candidates at redshifts 0.3 < z < 1.0. We compare the AGN hosts with a sample of nonactive galaxies drawn from the COSMOS field to match the magnitude and redshift distribution of the AGN hosts. We perform two-dimensional surface brightness modeling with GALFIT to yield host galaxy and nuclear point source magnitudes. X-ray-selected AGN host galaxy morphologies span a substantial range that peaks between those of early-type, bulge-dominated and late-type, disk-dominated systems. We also measure the asymmetry and concentration of the host galaxies. Unaccounted for, the nuclear point source can significantly bias results of these measured structural parameters, so we subtract the best-fit point source component to obtain images of the underlying host galaxies. Our concentration measurements reinforce the findings of our two-dimensional morphology fits, placing X-ray AGN hosts between early- and late-type inactive galaxies. AGN host asymmetry distributions are consistent with those of control galaxies. Combined with a lack of excess companion galaxies around AGN, the asymmetry distributions indicate that strong interactions are no more prevalent among AGN than normal galaxies. In light of recent work, these results suggest that the host galaxies of AGN at these X-ray luminosities may be in a transition from disk-dominated to bulge-dominated, but that this transition is not typically triggered by major mergers.

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Journal Article
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The Astrophysical Journal
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19 Sep 2018 15:32
Last Modified:
18 Nov 2020 06:09