Properties of Galaxies Hosting X-ray Selected Active Galactic Nuclei in the Cl1604 Supercluster at z=0.9 - AstrophysicsReport as inadecuate

Properties of Galaxies Hosting X-ray Selected Active Galactic Nuclei in the Cl1604 Supercluster at z=0.9 - Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: To investigate the role of feedback from Active Galactic Nuclei AGN indriving the evolution of their host galaxies, we have carried out a study ofthe environments and optical properties of galaxies harboring X-ray luminousAGN in the Cl1604 supercluster at z~0.9. Making use of Chandra, HST-ACS andKeck-DEIMOS observations, we examine the integrated colors, morphologies andspectral properties of nine moderate-luminosity L x ~ 10^43 erg s^-1 type 2Seyferts detected in the Cl1604 complex. We find that the AGN are predominantlyhosted by luminous spheroids and-or bulge dominated galaxies which have colorsthat place them in the valley between the blue cloud and red sequence incolor-magnitude space, consistent with predictions that AGN hosts shouldconstitute a transition population. Half of the hosts have bluer overall colorsas a result of blue resolved cores in otherwise red spheroids and a majorityshow signs of recent or pending interactions. We also find a substantial numberexhibit strong Balmer absorption features indicative of post-starburstgalaxies, despite the fact that we detect narrow OII emission lines in all ofthe host spectra. If the OII lines are due in part to AGN emission, as wesuspect, then this result implies that a significant fraction of these galaxies44% have experienced an enhanced level of star formation within the last ~1Gyr which was rapidly suppressed. Overall we find that the properties of thenine host galaxies are generally consistent with a scenario in which recentinteractions have triggered both increased levels of nuclear activity and anenhancement of centrally concentrated star formation, followed by a rapidtruncation of the latter, possibly as a result of feedback from the AGN itself.Abridged

Author: Dale D. Kocevski, Lori M. Lubin, Brian C. Lemaux, Roy Gal, Christopher D. Fassnacht, Robin Lin, Gordon K. Squires



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