WIDESPREAD AND HIDDEN ACTIVE GALACTIC NUCLEI IN STAR-FORMING GALAXIES AT REDSHIFT >0.3

Journal Article · Wed Feb 20 00:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/764/2/176· OSTI ID:22167695

Juneau, Stephanie; Bournaud, Frederic; Daddi, Emanuele; Elbaz, David ^[1]; Dickinson, Mark; Kartaltepe, Jeyhan S. ^[2]; Alexander, David M.; Mullaney, James R. ^[3]; Magnelli, Benjamin ^[4]; Hwang, Ho Seong; Willner, S. P. ^[5]; Coil, Alison L. ^[6]; Rosario, David J. ^[7]; Trump, Jonathan R.; Faber, S. M.; Kocevski, Dale D. ^[8]; Weiner, Benjamin J.; Willmer, Christopher N. A. ^[9]; Cooper, Michael C. ^[10]; others, and

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1. CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France)
2. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
3. Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
4. Max-Planck-Instituet fuer extraterrestrische Physik, Postfach 1312, D-85741 Garching bei Muenchen (Germany)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
6. Department of Physics, Center for Astrophysics and Space Sciences, University of California, 9500 Gilman Dr., La Jolla, San Diego, CA 92093 (United States)
7. Max-Planck-Instituet fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching bei Muenchen (Germany)
8. University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
9. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
10. Center for Galaxy Evolution, Department of Physics and Astronomy, University of California-Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States)

We characterize the incidence of active galactic nuclei (AGNs) in 0.3 < z < 1 star-forming galaxies by applying multi-wavelength AGN diagnostics (X-ray, optical, mid-infrared, radio) to a sample of galaxies selected at 70 {mu}m from the Far-Infrared Deep Extragalactic Legacy survey (FIDEL). Given the depth of FIDEL, we detect 'normal' galaxies on the specific star formation rate (sSFR) sequence as well as starbursting systems with elevated sSFR. We find an overall high occurrence of AGN of 37% {+-} 3%, more than twice as high as in previous studies of galaxies with comparable infrared luminosities and redshifts but in good agreement with the AGN fraction of nearby (0.05 < z < 0.1) galaxies of similar infrared luminosities. The more complete census of AGNs comes from using the recently developed Mass-Excitation (MEx) diagnostic diagram. This optical diagnostic is also sensitive to X-ray weak AGNs and X-ray absorbed AGNs, and reveals that absorbed active nuclei reside almost exclusively in infrared-luminous hosts. The fraction of galaxies hosting an AGN appears to be independent of sSFR and remains elevated both on the sSFR sequence and above. In contrast, the fraction of AGNs that are X-ray absorbed increases substantially with increasing sSFR, possibly due to an increased gas fraction and/or gas density in the host galaxies.

• OSTI ID: 22167695
• Journal Information: Astrophysical Journal, Vol. 764, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
COMPARATIVE EVALUATIONS
DENSITY
DIAGRAMS
EXCITATION
GALACTIC EVOLUTION
GALAXIES
GALAXY NUCLEI
LUMINOSITY
MASS
RED SHIFT
STAR EVOLUTION
STARS
X RADIATION