%0 Generic %1 olsen2012evidence %A Olsen, Karen Pardos %A Rasmussen, Jesper %A Toft, Sune %A Zirm, Andrew W. %D 2012 %K agn galaxy high-z host xrays %T Evidence for Widespread AGN Activity among Massive Quiescent Galaxies at z ~ 2 %U http://arxiv.org/abs/1212.1158 %X We quantify the presence of Active Galactic nuclei (AGN) in a mass-complete (M_* >5e10 M_sun) sample of 123 star-forming and quiescent galaxies at 1.5 < z < 2.5, using X-ray data from the 4 Ms Chandra Deep Field-South (CDF-S) survey. 41+/-7% of the galaxies are detected directly in X-rays, 22+/-5% with rest-frame 0.5-8 keV luminosities consistent with hosting luminous AGN (L_0.5-8keV > 3e42 ergs/s). The latter fraction is similar for star-forming and quiescent galaxies, and does not depend on galaxy stellar mass, suggesting that perhaps luminous AGN are triggered by external effects such as mergers. We detect significant mean X-ray signals in stacked images for both the individually non-detected star-forming and quiescent galaxies, with spectra consistent with star formation only and/or a low luminosity AGN in both cases. Comparing star formation rates inferred from the 2-10 keV luminosities to those from rest-frame IR+UV emission, we find evidence for an X-ray excess indicative of low-luminosity AGN. Among the quiescent galaxies, the excess suggests that as many as 70-100% of these contain low- or high-luminosity AGN, while the corresponding fraction is lower among star-forming galaxies (43-65%). The ubiquitous presence of AGN in massive, quiescent z ~ 2 galaxies that we find provides observational support for the importance of AGN in impeding star formation during galaxy evolution.

@misc{olsen2012evidence, abstract = {We quantify the presence of Active Galactic nuclei (AGN) in a mass-complete (M_* >5e10 M_sun) sample of 123 star-forming and quiescent galaxies at 1.5 < z < 2.5, using X-ray data from the 4 Ms Chandra Deep Field-South (CDF-S) survey. 41+/-7% of the galaxies are detected directly in X-rays, 22+/-5% with rest-frame 0.5-8 keV luminosities consistent with hosting luminous AGN (L_0.5-8keV > 3e42 ergs/s). The latter fraction is similar for star-forming and quiescent galaxies, and does not depend on galaxy stellar mass, suggesting that perhaps luminous AGN are triggered by external effects such as mergers. We detect significant mean X-ray signals in stacked images for both the individually non-detected star-forming and quiescent galaxies, with spectra consistent with star formation only and/or a low luminosity AGN in both cases. Comparing star formation rates inferred from the 2-10 keV luminosities to those from rest-frame IR+UV emission, we find evidence for an X-ray excess indicative of low-luminosity AGN. Among the quiescent galaxies, the excess suggests that as many as 70-100% of these contain low- or high-luminosity AGN, while the corresponding fraction is lower among star-forming galaxies (43-65%). The ubiquitous presence of AGN in massive, quiescent z ~ 2 galaxies that we find provides observational support for the importance of AGN in impeding star formation during galaxy evolution.}, added-at = {2012-12-07T16:33:20.000+0100}, author = {Olsen, Karen Pardos and Rasmussen, Jesper and Toft, Sune and Zirm, Andrew W.}, biburl = {https://www.bibsonomy.org/bibtex/292a3c6935739bdbfb4b7429de7bb2414/miki}, description = {[1212.1158] Evidence for Widespread AGN Activity among Massive Quiescent Galaxies at z ~ 2}, interhash = {25349be74963c9fff2b87cae8a6d0cba}, intrahash = {92a3c6935739bdbfb4b7429de7bb2414}, keywords = {agn galaxy high-z host xrays}, note = {cite arxiv:1212.1158Comment: 9 pages, 3 figures, 3 tables; Accepted for publication in ApJ}, timestamp = {2012-12-07T16:33:20.000+0100}, title = {Evidence for Widespread AGN Activity among Massive Quiescent Galaxies at z ~ 2}, url = {http://arxiv.org/abs/1212.1158}, year = 2012 }