The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS

A. Bongiorno; M. Mignoli; G. Zamorani; F. Lamareille; G. Lanzuisi; T. Miyaji; M. Bolzonella; C. M. Carollo; T. Contini; J. P. Kneib; O. Le Fèvre; S. J. Lilly; V. Mainieri; A. Renzini; M. Scodeggio; S. Bardelli; M. Brusa; K. Caputi; F. Civano; G. Coppa; O. Cucciati; S. de la Torre; L. de Ravel; P. Franzetti; B. Garilli; C. Halliday; G. Hasinger; A. M. Koekemoer; A. Iovino; P. Kampczyk; C. Knobel; K. Kovač; J. -F. Le Borgne; V. Le Brun; C. Maier; A. Merloni; P. Nair; R. Pello; Y. Peng; E. Perez Montero; E. Ricciardelli; M. Salvato; J. Silverman; M. Tanaka; L. Tasca; L. Tresse; D. Vergani; E. Zucca; U. Abbas; D. Bottini; A. Cappi; P. Cassata; A. Cimatti; L. Guzzo; A. Leauthaud; D. Maccagni; C. Marinoni; H. J. McCracken; P. Memeo; B. Meneux; P. Oesch; C. Porciani; L. Pozzetti; R. Scaramella

doi:10.1051/0004-6361/200913229

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Volume 510 (February 2010)

A&A, 510 (2010) A56

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Issue		A&A Volume 510, February 2010


Article Number		A56
Number of page(s)		15
Section		Extragalactic astronomy
DOI		https://doi.org/10.1051/0004-6361/200913229
Published online		09 February 2010

A&A 510, A56 (2010)

The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS $^{\rm,}$ ^*,^**

A. Bongiorno¹^,2, M. Mignoli³, G. Zamorani³, F. Lamareille⁴, G. Lanzuisi⁵^,6, T. Miyaji⁷^,8, M. Bolzonella³, C. M. Carollo⁹, T. Contini⁴, J. P. Kneib¹⁰, O. Le Fèvre¹⁰, S. J. Lilly⁹, V. Mainieri¹¹, A. Renzini¹², M. Scodeggio¹³, S. Bardelli³, M. Brusa¹, K. Caputi⁹, F. Civano⁵, G. Coppa³^,14, O. Cucciati¹⁰, S. de la Torre¹⁰^,13^,15, L. de Ravel¹⁰, P. Franzetti¹³, B. Garilli¹³, C. Halliday¹⁶, G. Hasinger¹^,17, A. M. Koekemoer¹⁸, A. Iovino¹³, P. Kampczyk⁹, C. Knobel⁹, K. Kovač⁹, J. -F. Le Borgne⁴, V. Le Brun¹⁰, C. Maier⁹, A. Merloni¹^,19, P. Nair³, R. Pello⁴, Y. Peng⁹, E. Perez Montero⁴^,20, E. Ricciardelli²¹, M. Salvato¹⁷^,19^,22, J. Silverman⁹, M. Tanaka¹¹, L. Tasca¹⁰^,13, L. Tresse¹⁰, D. Vergani³, E. Zucca³, U. Abbas¹⁰, D. Bottini¹³, A. Cappi³, P. Cassata¹⁰^,23, A. Cimatti¹⁴, L. Guzzo¹⁶, A. Leauthaud¹⁰, D. Maccagni¹³, C. Marinoni²⁴, H. J. McCracken²⁵, P. Memeo¹³, B. Meneux¹, P. Oesch⁹, C. Porciani⁹, L. Pozzetti³ and R. Scaramella²⁶

¹ Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstraße 1, 85748 Garching bei München, Germany e-mail: angelab@mpe.mpg.de
² University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD21250, USA
³ INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁴ Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 avenue Edouard Belin, 31400 Toulouse, France
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
⁶ Dipartimento di Fisica, Università di Roma La Sapienza, P.le A. Moro 2, 00185 Roma, Italy
⁷ Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, México, (mailing address: PO Box 439027, San Ysidro, CA, 92143-9027, USA)
⁸ University of California, San Diego, Center for Astrophysics and Space Sciences, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA
⁹ Department of Physics, ETH Zurich, 8093 Zurich, Switzerland
¹⁰ Laboratoire d'Astrophysique de Marseille, CNRS-Université d'Aix-Marseille, 38 rue Frédéric Joliot Curie, 13388 Marseille Cedex 13, France
¹¹ ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
¹² INAF - Osservatorio Astronomico di Padova, Padova, Italy
¹³ INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, via Bassini 15, 20133, Milano, Italy
¹⁴ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127, Bologna, Italy
¹⁵ INAF Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
¹⁶ Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
¹⁷ Max-Planck-Institute für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching bei München, Germany
¹⁸ Space Telescope Science Institute, 3700 Martin Drive, Baltimore, MD 21218, USA
¹⁹ Excellence Cluster Universe, TUM, Boltzmannstr. 2, 85748 Garching bei München, Germany
²⁰ Instituto de Astrofisica de Andalucia, CSIC, Apdo. 3004, 18080 Granada, Spain
²¹ Dipartimento di Astronomia, Università di Padova, vicolo Osservatorio 3, 35122 Padova, Italy
²² California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125, USA
²³ Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, USA
²⁴ Centre de Physique Théorique, Marseille, France
²⁵ Institut d'Astrophysique de Paris, Université Pierre & Marie Curie, Paris, France
²⁶ INAF - Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monteporzio Catone, Italy

Received: 2 September 2009
Accepted: 17 November 2009

Abstract

Aims. We present a catalog of 213 type-2 AGN selected from the zCOSMOS survey. The selected sample covers a wide redshift range (0.15 < z < 0.92) and is deeper than any other previous study, encompassing the luminosity range $10^{5.5}$ $L_{\odot}$ < $L_{\rm [OIII]}$ < $10^{9.1}$ $L_{\odot}$ . We explore the intrinsic properties of these AGN and the relation to their X-ray emission (derived from the XMM-COSMOS observations). We study their evolution by computing the [O iii]λ5007 $~\AA$ line luminosity function (LF) and we constrain the fraction of obscured AGN as a function of luminosity and redshift.

Methods. The sample was selected on the basis of the optical emission line ratios, after applying a cut to the signal-to-noise ratio (S/N) of the relevant lines. We used the standard diagnostic diagrams ([O iii]/H ${\beta}$ versus [N ii]/H ${\alpha}$ and [O iii]/H ${\beta}$ versus [S ii]/H ${\alpha}$ ) to isolate AGN in the redshift range 0.15 < z < 0.45 and the diagnostic diagram [O iii]/H ${\beta}$ versus [O ii]/H ${\beta}$ to extend the selection to higher redshift (0.5 < z < 0.92).

Results. Combining our sample with one drawn from SDSS, we found that the best description of the evolution of type-2 AGN is a luminosity-dependent density evolution model. Moreover, using the type-1 AGN LF we were able to constrain the fraction of type-2 AGN to the total (type-1 + type-2) AGN population. We found that the type-2 fraction decreases with luminosity, in agreement with the most recent results, and shows signs of a slight increase with redshift. However, the trend with luminosity is visible only after combining the SDSS+zCOSMOS samples. From the COSMOS data points alone, the type-2 fraction seems to be quite constant with luminosity.

Key words: surveys / galaxies: active

^*

Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 175.A-0839.

^**

Appendix A is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/510/A56

© ESO, 2010

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The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS*,**

The [O iii] emission line luminosity function of optically selected type-2 AGN from zCOSMOS $^{\rm,}$ ^*,^**