Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples

M. Salvato, O. Ilbert, G. Hasinger, A. Rau, F. Civano, G. Zamorani, M. Brusa, M. Elvis, C. Vignali, H. Aussel, A. Comastri, F. Fiore, E. Le Floc'H, V. Mainieri, S. Bardelli, M. Bolzonella, A. Bongiorno, P. Capak, K. Caputi, Nico CappellutiC. M. Carollo, T. Contini, B. Garilli, A. Iovino, S. Fotopoulou, A. Fruscione, R. Gilli, C. Halliday, J. P. Kneib, Y. Kakazu, J. S. Kartaltepe, A. M. Koekemoer, K. Kovac, Y. Ideue, H. Ikeda, C. D. Impey, O. Le Fevre, F. Lamareille, G. Lanzuisi, J. F. Le Borgne, V. Le Brun, S. Lilly, C. Maier, S. Manohar, D. Masters, H. McCracken, H. Messias, M. Mignoli, B. Mobasher, T. Nagao, R. Pello, S. Puccetti, E. Perez-Montero, A. Renzini, M. Sargent, D. B. Sanders, M. Scodeggio, N. Scoville, P. Shopbell, J. Silvermann, Y. Taniguchi, L. Tasca, L. Tresse, J. R. Trump, E. Zucca

Research output: Contribution to journalArticle

154 Citations (Scopus)

Abstract

In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2deg2 of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H AB = 24mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.

Original languageEnglish (US)
Article number61
JournalAstrophysical Journal
Volume742
Issue number2
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

Fingerprint

cosmos
XMM-Newton telescope
active galactic nuclei
outlier
field survey
targeting
radio
education
galaxies
x rays
energy
photometry
availability
templates
universe
luminosity
inclusions
library

Keywords

  • galaxies: active
  • galaxies: distances and redshifts
  • methods: data analysis
  • surveys techniques: photometric
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Salvato, M., Ilbert, O., Hasinger, G., Rau, A., Civano, F., Zamorani, G., ... Zucca, E. (2011). Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples. Astrophysical Journal, 742(2), [61]. https://doi.org/10.1088/0004-637X/742/2/61

Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples. / Salvato, M.; Ilbert, O.; Hasinger, G.; Rau, A.; Civano, F.; Zamorani, G.; Brusa, M.; Elvis, M.; Vignali, C.; Aussel, H.; Comastri, A.; Fiore, F.; Le Floc'H, E.; Mainieri, V.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Capak, P.; Caputi, K.; Cappelluti, Nico; Carollo, C. M.; Contini, T.; Garilli, B.; Iovino, A.; Fotopoulou, S.; Fruscione, A.; Gilli, R.; Halliday, C.; Kneib, J. P.; Kakazu, Y.; Kartaltepe, J. S.; Koekemoer, A. M.; Kovac, K.; Ideue, Y.; Ikeda, H.; Impey, C. D.; Le Fevre, O.; Lamareille, F.; Lanzuisi, G.; Le Borgne, J. F.; Le Brun, V.; Lilly, S.; Maier, C.; Manohar, S.; Masters, D.; McCracken, H.; Messias, H.; Mignoli, M.; Mobasher, B.; Nagao, T.; Pello, R.; Puccetti, S.; Perez-Montero, E.; Renzini, A.; Sargent, M.; Sanders, D. B.; Scodeggio, M.; Scoville, N.; Shopbell, P.; Silvermann, J.; Taniguchi, Y.; Tasca, L.; Tresse, L.; Trump, J. R.; Zucca, E.

In: Astrophysical Journal, Vol. 742, No. 2, 61, 01.12.2011.

Research output: Contribution to journalArticle

Salvato, M, Ilbert, O, Hasinger, G, Rau, A, Civano, F, Zamorani, G, Brusa, M, Elvis, M, Vignali, C, Aussel, H, Comastri, A, Fiore, F, Le Floc'H, E, Mainieri, V, Bardelli, S, Bolzonella, M, Bongiorno, A, Capak, P, Caputi, K, Cappelluti, N, Carollo, CM, Contini, T, Garilli, B, Iovino, A, Fotopoulou, S, Fruscione, A, Gilli, R, Halliday, C, Kneib, JP, Kakazu, Y, Kartaltepe, JS, Koekemoer, AM, Kovac, K, Ideue, Y, Ikeda, H, Impey, CD, Le Fevre, O, Lamareille, F, Lanzuisi, G, Le Borgne, JF, Le Brun, V, Lilly, S, Maier, C, Manohar, S, Masters, D, McCracken, H, Messias, H, Mignoli, M, Mobasher, B, Nagao, T, Pello, R, Puccetti, S, Perez-Montero, E, Renzini, A, Sargent, M, Sanders, DB, Scodeggio, M, Scoville, N, Shopbell, P, Silvermann, J, Taniguchi, Y, Tasca, L, Tresse, L, Trump, JR & Zucca, E 2011, 'Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples', Astrophysical Journal, vol. 742, no. 2, 61. https://doi.org/10.1088/0004-637X/742/2/61
Salvato, M. ; Ilbert, O. ; Hasinger, G. ; Rau, A. ; Civano, F. ; Zamorani, G. ; Brusa, M. ; Elvis, M. ; Vignali, C. ; Aussel, H. ; Comastri, A. ; Fiore, F. ; Le Floc'H, E. ; Mainieri, V. ; Bardelli, S. ; Bolzonella, M. ; Bongiorno, A. ; Capak, P. ; Caputi, K. ; Cappelluti, Nico ; Carollo, C. M. ; Contini, T. ; Garilli, B. ; Iovino, A. ; Fotopoulou, S. ; Fruscione, A. ; Gilli, R. ; Halliday, C. ; Kneib, J. P. ; Kakazu, Y. ; Kartaltepe, J. S. ; Koekemoer, A. M. ; Kovac, K. ; Ideue, Y. ; Ikeda, H. ; Impey, C. D. ; Le Fevre, O. ; Lamareille, F. ; Lanzuisi, G. ; Le Borgne, J. F. ; Le Brun, V. ; Lilly, S. ; Maier, C. ; Manohar, S. ; Masters, D. ; McCracken, H. ; Messias, H. ; Mignoli, M. ; Mobasher, B. ; Nagao, T. ; Pello, R. ; Puccetti, S. ; Perez-Montero, E. ; Renzini, A. ; Sargent, M. ; Sanders, D. B. ; Scodeggio, M. ; Scoville, N. ; Shopbell, P. ; Silvermann, J. ; Taniguchi, Y. ; Tasca, L. ; Tresse, L. ; Trump, J. R. ; Zucca, E. / Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples. In: Astrophysical Journal. 2011 ; Vol. 742, No. 2.
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T1 - Dissecting photometric redshift for active galactic nucleus using XMM- and Chandra-cosmos samples

AU - Salvato, M.

AU - Ilbert, O.

AU - Hasinger, G.

AU - Rau, A.

AU - Civano, F.

AU - Zamorani, G.

AU - Brusa, M.

AU - Elvis, M.

AU - Vignali, C.

AU - Aussel, H.

AU - Comastri, A.

AU - Fiore, F.

AU - Le Floc'H, E.

AU - Mainieri, V.

AU - Bardelli, S.

AU - Bolzonella, M.

AU - Bongiorno, A.

AU - Capak, P.

AU - Caputi, K.

AU - Cappelluti, Nico

AU - Carollo, C. M.

AU - Contini, T.

AU - Garilli, B.

AU - Iovino, A.

AU - Fotopoulou, S.

AU - Fruscione, A.

AU - Gilli, R.

AU - Halliday, C.

AU - Kneib, J. P.

AU - Kakazu, Y.

AU - Kartaltepe, J. S.

AU - Koekemoer, A. M.

AU - Kovac, K.

AU - Ideue, Y.

AU - Ikeda, H.

AU - Impey, C. D.

AU - Le Fevre, O.

AU - Lamareille, F.

AU - Lanzuisi, G.

AU - Le Borgne, J. F.

AU - Le Brun, V.

AU - Lilly, S.

AU - Maier, C.

AU - Manohar, S.

AU - Masters, D.

AU - McCracken, H.

AU - Messias, H.

AU - Mignoli, M.

AU - Mobasher, B.

AU - Nagao, T.

AU - Pello, R.

AU - Puccetti, S.

AU - Perez-Montero, E.

AU - Renzini, A.

AU - Sargent, M.

AU - Sanders, D. B.

AU - Scodeggio, M.

AU - Scoville, N.

AU - Shopbell, P.

AU - Silvermann, J.

AU - Taniguchi, Y.

AU - Tasca, L.

AU - Tresse, L.

AU - Trump, J. R.

AU - Zucca, E.

PY - 2011/12/1

Y1 - 2011/12/1

N2 - In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2deg2 of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H AB = 24mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.

AB - In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2deg2 of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H AB = 24mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.

KW - galaxies: active

KW - galaxies: distances and redshifts

KW - methods: data analysis

KW - surveys techniques: photometric

KW - X-rays: galaxies

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