Active galactic nucleus host galaxy morphologies in COSMOS

J. M. Gabor, C. D. Impey, K. Jahnke, B. D. Simmons, J. R. Trump, A. M. Koekemoer, M. Brusa, N. Cappelluti, E. Schinnerer, V. Smolčić, M. Salvato, J. D. Rhodes, B. Mobasher, P. Capak, R. Massey, A. Leauthaud, N. Scoville

Research output: Contribution to journalArticlepeer-review

164 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)705-722
Number of pages18
JournalAstrophysical Journal
Issue number1
StatePublished - Jan 20 2009


  • galaxies: active
  • galaxies: evolution
  • galaxies: interactions
  • galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Active galactic nucleus host galaxy morphologies in COSMOS'. Together they form a unique fingerprint.

Cite this