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Spectroscopic Identifications of Spitzer Sources in the SWIRE/XMM-Newton/ELAIS-S1 Field: A Large Fraction of Active Galactic Nucleus with High F(24 μm)/F(R) Ratio

Sacchi, N. and La Franca, F. and Feruglio, C. and Fiore, F. and Puccetti, S. and Cocchia, F. and Berta, S. and Brusa, M. and Cimatti, A. and Comastri, A. and Franceschini, A. and Gruppioni, C. and Maiolino, R. and Matute, I. and Polletta, M. and Pozzetti, L. and Pozzi, F. and Vignali, C. and Zamorani, G. and Oliver, S. and Rowan-Robinson, M. and G. Smith, G. and Lonsdale, C. (2009) Spectroscopic Identifications of Spitzer Sources in the SWIRE/XMM-Newton/ELAIS-S1 Field: A Large Fraction of Active Galactic Nucleus with High F(24 μm)/F(R) Ratio. Astrophysical Journal, 703 (2). pp. 1778-1790. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20091013-111837503

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Abstract

We present a catalog of optical spectroscopic identifications of sources detected by Spitzer at 3.6 or 24 μm down to ~10 and ~280 μJy, respectively, in the SWIRE/XMM-Newton/ELAIS-S1 field and classified via line width analysis and diagnostic diagrams. A total of 1376 sources down to R ~ 24.2 mag have been identified (1362 detected at 3.6 μm, 419 at 24 μm, and 405 at both) by low-resolution optical spectroscopy carried out with FORS2, VIMOS, and EFOSC2 at the Very Large Telescope and 3.6 m ESO telescope. The spectroscopic campaigns have been carried out over the central 0.6 deg^2 area of ELAIS-S1 which, in particular, has also been observed by XMM-Newton and Chandra. We find the first direct optical spectroscopic evidence that the fraction of active galactic nuclei (AGNs; mostly AGN2) increases with increasing F(24 μm)/F(R) ratio, reaching values of 70(±20)% in the range 316 < F(24 μm)/F(R) < 1000. We present an Infrared Array Camera-Multiband Imaging Photometer color-color diagram able to separate AGN1 from obscured AGN2 candidates. After having corrected for the spectroscopic incompleteness of our sample, the result is that the AGN fraction at F(24 μm) ~0.8 mJy is ~22(±7)% and decreases slowly to ~19(±5)% down to F(24 μm) ~ 0.3 mJy.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/703/2/1778 DOIArticle
http://www.iop.org/EJ/abstract/0004-637X/703/2/1778/PublisherArticle
ORCID:
AuthorORCID
Puccetti, S.0000-0002-2734-7835
Comastri, A.0000-0003-3451-9970
Gruppioni, C.0000-0002-5836-4056
Additional Information:© 2009 The American Astronomical Society. Received 2008 November 16; accepted 2009 July 23; published 2009 September 14. Based on observations made with the ESO telescopes at the La Silla and Paranal Observatories under program IDs 168.A- 0322, 170.A-0143, 073.A-0446, 075.A-0428, 076.A-0225, 077.A-0800, and 078.A-0795. Part of the data published in this paper have been reduced using VIPGI, designed by the VIRMOS Consortium and developed by INAF Milano. We are grateful to Bianca Garilli and Marco Scodeggio for the support provided in running the VIPGI pipeline. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. We acknowledge financial contribution from contract ASI-INAF I/023/05/0, PRIN-MIUR grant 2006-02-5203. The anonymous referee is acknowledged for his detailed and constructive reports. Facilities: VLT:Melipal (VIMOS), VLT:Antu (FORS2), ESO:3.6 m (EFOSC2), Spitzer.
Funders:
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)ASI-INAFI/023/05/0
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)2006-02-5203
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Subject Keywords:galaxies: active; infrared: galaxies; surveys
Record Number:CaltechAUTHORS:20091013-111837503
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20091013-111837503
Official Citation:Spectroscopic Identifications of Spitzer Sources in the SWIRE/XMM-Newton/ELAIS-S1 Field: A Large Fraction of Active Galactic Nucleus with High F(24 μm)/F(R) Ratio N. Sacchi, F. La Franca, C. Feruglio, F. Fiore, S. Puccetti, F. Cocchia, S. Berta, M. Brusa, A. Cimatti, A. Comastri, A. Franceschini, C. Gruppioni, R. Maiolino, I. Matute, M. Polletta, L. Pozzetti, F. Pozzi, C. Vignali, G. Zamorani, S. Oliver, M. Rowan-Robinson, G. Smith, and C. Lonsdale 2009 ApJ 703 1778-1790 doi: 10.1088/0004-637X/703/2/1778
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16325
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Oct 2009 16:19
Last Modified:30 Nov 2017 22:02

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