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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 660865.0, MPI für Astronomie / Publikationen_mpia
CANDELS: Constraining the AGN-merger connection with host morphologies at z ~ 2
Authors:Kocevski, D. D.; Faber, S. M.; Mozena, M.; Koekemoer, A. M.; Nandra, K.; Rangel, C.; Laird, E. S.; Brusa, M.; Wuyts, S.; Trump, J. R.; Koo, D. C.; Somerville, R. S.; Bell, E. F.; Lotz, J. M.; Alexander, D. M.; Bournaud, F.; Conselice, C. J.; Dahlen, T.; Dekel, A.; Donley, J. L.; Dunlop, J. S.; Finoguenov, A.; Georgakakis, A.; Giavalisco, M.; Guo, Y.; Grogin, N. A.; Hathi, N. P.; Juneau, S.; Kartaltepe, J. S.; Lucas, R. A.; McGrath, E. J.; McIntosh, D. H.; Mobasher, B.; Robaina, A. R.; Rosario, D.; Straughn, A. N.; van der Wel, A.; Villforth, C.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:The Astrophysical Journal
Volume:744
Issue / Number:2
Start Page:id. 148
Audience:Not Specified
Abstract / Description:Using Hubble Space Telescope/WFC3 imaging taken as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we examine the role that major galaxy mergers play in triggering active galactic nucleus (AGN) activity at z ~ 2. Our sample consists of 72 moderate-luminosity (L X ~ 1042-44 erg s-1) AGNs at 1.5 < z < 2.5 that are selected using the 4 Ms Chandra observations in the Chandra Deep Field South, the deepest X-ray observations to date. Employing visual classifications, we have analyzed the rest-frame optical morphologies of the AGN host galaxies and compared them to a mass-matched control sample of 216 non-active galaxies at the same redshift. We find that most of the AGNs reside in disk galaxies (51.4+5.8 - 5.9%), while a smaller percentage are found in spheroids (27.8+5.8 - 4.6%). Roughly 16.7+5.3 - 3.5% of the AGN hosts have highly disturbed morphologies and appear to be involved in a major merger or interaction, while most of the hosts (55.6+5.6 - 5.9%) appear relatively relaxed and undisturbed. These fractions are statistically consistent with the fraction of control galaxies that show similar morphological disturbances. These results suggest that the hosts of moderate-luminosity AGNs are no more likely to be involved in an ongoing merger or interaction relative to non-active galaxies of similar mass at z ~ 2. The high disk fraction observed among the AGN hosts also appears to be at odds with predictions that merger-driven accretion should be the dominant AGN fueling mode at z ~ 2, even at moderate X-ray luminosities. Although we cannot rule out that minor mergers are responsible for triggering these systems, the presence of a large population of relatively undisturbed disk-like hosts suggests that the stochastic accretion of gas plays a greater role in fueling AGN activity at z ~ 2 than previously thought.
Free Keywords:galaxies: active; galaxies: evolution; X-rays: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://cdsads.u-strasbg.fr/abs/2012ApJ...744..148K
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