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

Abstract

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 notmore » 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.« less

Authors:
; ;  [1];  [2]; ; ; ;  [3];  [4]; ; ;  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12];  [13]
  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)
Publication Date:
OSTI Identifier:
21612698
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 741; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/741/2/91; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Civano, F., Elvis, M., Hao, H., Brusa, M., Comastri, A., Zamorani, G., Gilli, R., Mignoli, M., Salvato, M., Capak, P., Kakazu, Y., Masters, D., Fiore, F., Ikeda, H., Kartaltepe, J. S., Miyaji, T., Puccetti, S., Shankar, F., Silverman, J., and Vignali, C.. THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY. United States: N. p., 2011. Web. doi:10.1088/0004-637X/741/2/91; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Civano, F., Elvis, M., Hao, H., Brusa, M., Comastri, A., Zamorani, G., Gilli, R., Mignoli, M., Salvato, M., Capak, P., Kakazu, Y., Masters, D., Fiore, F., Ikeda, H., Kartaltepe, J. S., Miyaji, T., Puccetti, S., Shankar, F., Silverman, J., & Vignali, C.. THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY. United States. doi:10.1088/0004-637X/741/2/91; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Civano, F., Elvis, M., Hao, H., Brusa, M., Comastri, A., Zamorani, G., Gilli, R., Mignoli, M., Salvato, M., Capak, P., Kakazu, Y., Masters, D., Fiore, F., Ikeda, H., Kartaltepe, J. S., Miyaji, T., Puccetti, S., Shankar, F., Silverman, J., and Vignali, C.. Thu . "THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY". United States. doi:10.1088/0004-637X/741/2/91; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21612698,
title = {THE POPULATION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE CHANDRA-COSMOS SURVEY},
author = {Civano, F. and Elvis, M. and Hao, H. and Brusa, M. and Comastri, A. and Zamorani, G. and Gilli, R. and Mignoli, M. and Salvato, M. and Capak, P. and Kakazu, Y. and Masters, D. and Fiore, F. and Ikeda, H. and Kartaltepe, J. S. and Miyaji, T. and Puccetti, S. and Shankar, F. and Silverman, J. and Vignali, C.},
abstractNote = {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.},
doi = {10.1088/0004-637X/741/2/91; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
number = 2,
volume = 741,
place = {United States},
year = {Thu Nov 10 00:00:00 EST 2011},
month = {Thu Nov 10 00:00:00 EST 2011}
}