Evidence for Widespread AGN Activity among Massive Quiescent Galaxies at
z ~ 2
K. Olsen, J. Rasmussen, S. Toft, and A. Zirm. (2012)cite arxiv:1212.1158Comment: 9 pages, 3 figures, 3 tables; Accepted for publication in ApJ.
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.
Description
[1212.1158] Evidence for Widespread AGN Activity among Massive Quiescent Galaxies at z ~ 2
%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
}