THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY

Journal Article · Thu Nov 10 00:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/2/91; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612698

Civano, F; Elvis, M; Hao, H ^[1]; Brusa, M ^[2]; Comastri, A; Zamorani, G; Gilli, R; Mignoli, M ^[3]; Salvato, M ^[4]; Capak, P; Kakazu, Y; Masters, D ^[5]; Fiore, F ^[6]; Ikeda, H ^[7]; Kartaltepe, J S ^[8]; Miyaji, T ^[9]; Puccetti, S ^[10]; Shankar, F ^[11]; Silverman, J ^[12]; Vignali, C ^[13]

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1. Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
2. Max Planck Institut fuer Extraterrestrische Physik Giessenbach strasse 1, D-85748 Garching (Germany)
3. INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
4. Max-Planck-Institute for Plasma Physics, Boltzmannstrass 2, Garching D-85748 (Germany)
5. California Institute of Technology, 1201 East California Boulevard, Pasadena, CA 91125 (United States)
6. INAF-Osservatorio Astronomico di Roma, via Frascati 33, Monteporzio-Catone (Roma) I-00040 (Italy)
7. Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan)
8. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
9. Instituto de Astronomia, Universidad Nacional Autonoma de Mexico-Ensenada, Km. 103 Carretera Tijuana-Ensenada, 22860 Ensenada (Mexico)
10. ASI Science Data Center, via Galileo Galilei, 00044 Frascati (Italy)
11. Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)
12. Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8568 (Japan)
13. Dipartimento di Astronomia, Universita di Bologna, via Ranzani 1, 40127 Bologna (Italy)

We present the high-redshift (3 <z < 5.3) 0.5-2 keV number counts and the 2-10 keV (rest-frame) space density of X-ray-selected active galactic nuclei (AGNs) detected in the Chandra Cosmic Evolution Survey. The sample comprises 81 X-ray-detected sources with available spectroscopic (31) and photometric (50) redshifts plus 20 sources with a formal z{sub phot} < 3 but with a broad photometric redshift probability distribution, such that z{sub phot} + 1{sigma} > 3. Eighty-one sources are selected in the 0.5-2 keV band, fourteen are selected in the 2-10 keV and six in the 0.5-10 keV bands. We sample the high-luminosity (log L{sub (2-10keV)} > 44.15 erg s{sup -1}) space density up to z {approx} 5 and a fainter luminosity range (43.5 erg s{sup -1} < log L{sub (2-10keV)} < 44.15 erg s{sup -1}) than previous studies, up to z = 3.5. We weighted the contribution to the number counts and the space density of the sources with photometric redshift by using their probability of being at z > 3. We find that the space density of high-luminosity AGNs declines exponentially at all the redshifts, confirming the trend observed for optically selected quasars. At lower luminosity, the measured space density is not conclusive, and a larger sample of faint sources is needed. Comparisons with optical luminosity functions and black hole formation models are presented together with prospects for future surveys.

• OSTI ID: 21612698
• Journal Information: Astrophysical Journal, Vol. 741, Issue 2; Other Information: DOI: 10.1088/0004-637X/741/2/91; 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
BLACK HOLES
GALACTIC EVOLUTION
GALAXY NUCLEI
LUMINOSITY
QUASARS
RED SHIFT
UNIVERSE
X-RAY GALAXIES
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
EVOLUTION
GALAXIES
OPTICAL PROPERTIES
PHYSICAL PROPERTIES