The Evolution of Agn Host Galaxies : from Blue to Red and the Influence of Large-scale Structures

Content Provider	Semantic Scholar
Author	Silverman, Danielle Mainieri, V. Lehmer, B. D. Alexander, David M. Bauer, Franz Erik Bergeron, Jacqueline Brandt, William N. Gilli, Roberto Hasinger, Guenther Schneider, Donald P. Tozzi, Paolo Vignali, Cristian Koekemoer, Anton M. Miyaji, Takamitsu Popesso, P. Rosati, Piero Szokoly, G.
Copyright Year	2008
Abstract	We present an analysis of 109 moderate-luminosity (41:9 log L0:5Y 8:0 keV 43:7) AGNs in the Extended Chandra Deep Field-South survey, which is drawn from 5549 galaxies from the COMBO-17 and GEMS surveys having 0:4 z 1:1. These obscured or optically weak AGNs facilitate the study of their host galaxies since the AGNs provide an insubstantial amount of contamination to the galaxy light. We find that the color distribution of AGN host galaxies is highly dependent on (1) the strong color-evolution of luminous (MV < 20:7) galaxies, and (2) the influence of 10Mpc scale structures. When excluding galaxies within the redshift range 0:63 z 0:76, a regime dominated by sources in large-scale structures at z 1⁄4 0:67 and z 1⁄4 0:73, we observe a bimodality in the host galaxy colors. Galaxies hosting AGNs at zk 0:8 preferentially have bluer (rest-frame U V < 0:7) colors than their zP 0:6 counterparts (many of which fall along the red sequence). The fraction of galaxies hosting AGNs peaks in the ‘‘green valley’’ (0:5 < U V < 1:0); this is primarily due to enhancedAGN activity in the redshift interval 0:63 z 0:76. The AGN fraction in this redshift and color interval is 12.8% (compared to its ‘‘field’’ value of 7.8%) and reaches a maximum of 14.8% at U V 0:8. We further find that blue, bulge-dominated (Sérsic index n > 2:5) galaxies have the highest fraction of AGN (21%) in our sample. We explore the scenario that the evolution of AGN hosts is driven by galaxy mergers and illustrate that an accurate assessment requires a larger area survey since only three hosts may be undergoing a merger with timescales P1 Gyr following a starburst phase. Subject headinggs: galaxies: active — galaxies: evolution — large-scale structure of universe — quasars: general — X-rays: galaxies
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Alternate Webpage(s)	http://dro.dur.ac.uk/11255/1/11255.pdf?DDD25+cqjd36=
Alternate Webpage(s)	http://arxiv.org/pdf/0709.3455v2.pdf
Alternate Webpage(s)	http://arxiv.org/pdf/0709.3455v1.pdf
Language	English
Access Restriction	Open
Subject Keyword	Active galactic nucleus Biological Evolution Color Galaxy Kiloelectronvolt Large Luminous Studio Medical Subject Headings Methylene blue Radiation Redshift
Content Type	Text
Resource Type	Article