THE SPITZER MID-INFRARED ACTIVE GALACTIC NUCLEUS SURVEY. I. OPTICAL AND NEAR-INFRARED SPECTROSCOPY OF OBSCURED CANDIDATES AND NORMAL ACTIVE GALACTIC NUCLEI SELECTED IN THE MID-INFRARED

Journal Article · Tue Oct 01 04:00:00 EDT 2013 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/208/2/24· OSTI ID:22273310

Lacy, M. ^[1]; Ridgway, S. E. ^[2]; Gates, E. L. ^[3]; Nielsen, D. M. ^[4]; Petric, A. O. ^[5]; Sajina, A. ^[6]; Urrutia, T. ^[7]; Cox Drews, S. ^[8]; Harrison, C. ^[9]; Seymour, N. ^[10]; Storrie-Lombardi, L. J. ^[11]

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1. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
2. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
3. UCO/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States)
4. Department of Astronomy, University of Wisconsin, 475 N. Charter Street, Madison, WI 53706 (United States)
5. Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
6. Department of Physics and Astronomy, Tuffs University, 212 College Avenue, Medford, MA 02155 (United States)
7. Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
8. 946 Mangrove Avenue 102, Sunnyvale, CA 94086 (United States)
9. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
10. CSIRO, P.O. Box 76, Epping, NSW 1710 (Australia)
11. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)

We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L {sub bol} ∼ 10{sup 10} L {sub ☉} to highly luminous quasars (L {sub bol} ∼ 10{sup 14} L {sub ☉}), all with redshifts ranging from 0 to 4.3. Samples of candidate AGNs were selected with mid-infrared color cuts at several different 24 μm flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGNs and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type 1 AGNs with blue continua, 294 (44%) are type 2 objects with extinctions A{sub V} ∼> 5 toward their AGNs, 96 (14%) are AGNs with lower extinctions (A{sub V} ∼ 1), and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. Of the survey objects 50% have L {sub bol} > 10{sup 12} L {sub ☉}, in the quasar regime. We present composite spectra for type 2 quasars and objects with no signs of AGN activity in their spectra. We also discuss the mid-infrared—emission-line luminosity correlation and present the results of cross correlations with serendipitous X-ray and radio sources. The results show that: (1) obscured objects dominate the overall AGN population, (2) mid-infrared selected AGN candidates exist which lack AGN signatures in their optical spectra but have AGN-like X-ray or radio counterparts, and (3) X-ray and optical classifications of obscured and unobscured AGNs often differ.

• OSTI ID: 22273310
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 2 Vol. 208; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTROSCOPY
ASTRONOMY
ASTROPHYSICS
BOLOMETERS
COLOR
CORRELATIONS
FLUX DENSITY
GALAXY NUCLEI
INFRARED SPECTRA
LUMINOSITY
QUASARS
RED SHIFT
SEYFERT GALAXIES
X RADIATION