A large, uniform sample of X-ray-emitting AGNs: Selection approach and an initial catalog from the ROSAT all-sky and sloan digital sky surveys

Scott F. Anderson, Wolfgang Voges, Bruce Margon, Joachim Trümper, Marcel A. Agüeros, Thomas Boller, Matthew J. Collinge, L. Homer, Gregory Stinson, Michael A. Strauss, James Annis, Percy Gómez, Patrick B. Hall, Robert C. Nichol, Gordon T. Richards, Donald P. Schneider, Daniel E. Vanden Berk, Xiaohui Fan, Željko Ivezić, Jeffrey A. MunnHeidi Jo Newberg, Michael W. Richmond, David H. Weinberg, Brian Yanny, Neta A. Bahcall, J. Brinkmann, Masataka Fukugita, Donald G. York

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

Many open questions in X-ray astronomy are limited by the relatively small number of objects in uniform optically identified and observed samples, especially when rare subclasses are considered or when subsets are isolated to search for evolution or correlations between wavebands. We describe the initial results of a new program aimed to ultimately yield ∼10 4 fully characterized X-ray source identifications - a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of f x/f opt for various classes of X-ray emitters at typical RASS fluxes of ∼10 -13 ergs cm -2 s -1. SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class. Initial application of this approach to RASS/SDSS data from 1400 deg 2 of sky provides a catalog of more than 1200 spectroscopically confirmed quasars and other AGNs that are probable RASS identifications. Most of these are new identifications, and only a few percent of the AGN counterparts are likely to be random superpositions. The magnitude and redshift ranges of the counterparts are very broad, extending over 15 < m < 21 and 0.03 < z < 3.6, respectively. Although most identifications are quasars and Seyfert 1 galaxies, a variety of other AGN subclasses are also sampled. Substantial numbers of rare AGN types are found, including more than 130 narrow-line Seyfert 1 galaxies and 45 BL Lac candidates. These early results already provide a very sizable set of source identifications, demonstrate the utility of the sample in multiwaveband investigations, and show the capability of the joint RASS/SDSS approach to efficiently proceed toward the largest homogeneously selected/observed sample of X-ray-emitting quasars and other kinds of AGNs.

Original languageEnglish (US)
Pages (from-to)2209-2229
Number of pages21
JournalAstronomical Journal
Volume126
Issue number5 1775
DOIs
StatePublished - Nov 2003

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catalogs
sky
x rays
quasars
galaxies
astronomy
set theory
erg
optical spectrum
emitters
computer programs
color
radio
software

Keywords

  • Catalogs
  • Quasars: general
  • Surveys
  • X-rays

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Anderson, S. F., Voges, W., Margon, B., Trümper, J., Agüeros, M. A., Boller, T., ... York, D. G. (2003). A large, uniform sample of X-ray-emitting AGNs: Selection approach and an initial catalog from the ROSAT all-sky and sloan digital sky surveys. Astronomical Journal, 126(5 1775), 2209-2229. https://doi.org/10.1086/378999

A large, uniform sample of X-ray-emitting AGNs : Selection approach and an initial catalog from the ROSAT all-sky and sloan digital sky surveys. / Anderson, Scott F.; Voges, Wolfgang; Margon, Bruce; Trümper, Joachim; Agüeros, Marcel A.; Boller, Thomas; Collinge, Matthew J.; Homer, L.; Stinson, Gregory; Strauss, Michael A.; Annis, James; Gómez, Percy; Hall, Patrick B.; Nichol, Robert C.; Richards, Gordon T.; Schneider, Donald P.; Vanden Berk, Daniel E.; Fan, Xiaohui; Ivezić, Željko; Munn, Jeffrey A.; Newberg, Heidi Jo; Richmond, Michael W.; Weinberg, David H.; Yanny, Brian; Bahcall, Neta A.; Brinkmann, J.; Fukugita, Masataka; York, Donald G.

In: Astronomical Journal, Vol. 126, No. 5 1775, 11.2003, p. 2209-2229.

Research output: Contribution to journalArticle

Anderson, SF, Voges, W, Margon, B, Trümper, J, Agüeros, MA, Boller, T, Collinge, MJ, Homer, L, Stinson, G, Strauss, MA, Annis, J, Gómez, P, Hall, PB, Nichol, RC, Richards, GT, Schneider, DP, Vanden Berk, DE, Fan, X, Ivezić, Ž, Munn, JA, Newberg, HJ, Richmond, MW, Weinberg, DH, Yanny, B, Bahcall, NA, Brinkmann, J, Fukugita, M & York, DG 2003, 'A large, uniform sample of X-ray-emitting AGNs: Selection approach and an initial catalog from the ROSAT all-sky and sloan digital sky surveys', Astronomical Journal, vol. 126, no. 5 1775, pp. 2209-2229. https://doi.org/10.1086/378999
Anderson, Scott F. ; Voges, Wolfgang ; Margon, Bruce ; Trümper, Joachim ; Agüeros, Marcel A. ; Boller, Thomas ; Collinge, Matthew J. ; Homer, L. ; Stinson, Gregory ; Strauss, Michael A. ; Annis, James ; Gómez, Percy ; Hall, Patrick B. ; Nichol, Robert C. ; Richards, Gordon T. ; Schneider, Donald P. ; Vanden Berk, Daniel E. ; Fan, Xiaohui ; Ivezić, Željko ; Munn, Jeffrey A. ; Newberg, Heidi Jo ; Richmond, Michael W. ; Weinberg, David H. ; Yanny, Brian ; Bahcall, Neta A. ; Brinkmann, J. ; Fukugita, Masataka ; York, Donald G. / A large, uniform sample of X-ray-emitting AGNs : Selection approach and an initial catalog from the ROSAT all-sky and sloan digital sky surveys. In: Astronomical Journal. 2003 ; Vol. 126, No. 5 1775. pp. 2209-2229.
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AU - Voges, Wolfgang

AU - Margon, Bruce

AU - Trümper, Joachim

AU - Agüeros, Marcel A.

AU - Boller, Thomas

AU - Collinge, Matthew J.

AU - Homer, L.

AU - Stinson, Gregory

AU - Strauss, Michael A.

AU - Annis, James

AU - Gómez, Percy

AU - Hall, Patrick B.

AU - Nichol, Robert C.

AU - Richards, Gordon T.

AU - Schneider, Donald P.

AU - Vanden Berk, Daniel E.

AU - Fan, Xiaohui

AU - Ivezić, Željko

AU - Munn, Jeffrey A.

AU - Newberg, Heidi Jo

AU - Richmond, Michael W.

AU - Weinberg, David H.

AU - Yanny, Brian

AU - Bahcall, Neta A.

AU - Brinkmann, J.

AU - Fukugita, Masataka

AU - York, Donald G.

PY - 2003/11

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N2 - Many open questions in X-ray astronomy are limited by the relatively small number of objects in uniform optically identified and observed samples, especially when rare subclasses are considered or when subsets are isolated to search for evolution or correlations between wavebands. We describe the initial results of a new program aimed to ultimately yield ∼10 4 fully characterized X-ray source identifications - a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of f x/f opt for various classes of X-ray emitters at typical RASS fluxes of ∼10 -13 ergs cm -2 s -1. SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class. Initial application of this approach to RASS/SDSS data from 1400 deg 2 of sky provides a catalog of more than 1200 spectroscopically confirmed quasars and other AGNs that are probable RASS identifications. Most of these are new identifications, and only a few percent of the AGN counterparts are likely to be random superpositions. The magnitude and redshift ranges of the counterparts are very broad, extending over 15 < m < 21 and 0.03 < z < 3.6, respectively. Although most identifications are quasars and Seyfert 1 galaxies, a variety of other AGN subclasses are also sampled. Substantial numbers of rare AGN types are found, including more than 130 narrow-line Seyfert 1 galaxies and 45 BL Lac candidates. These early results already provide a very sizable set of source identifications, demonstrate the utility of the sample in multiwaveband investigations, and show the capability of the joint RASS/SDSS approach to efficiently proceed toward the largest homogeneously selected/observed sample of X-ray-emitting quasars and other kinds of AGNs.

AB - Many open questions in X-ray astronomy are limited by the relatively small number of objects in uniform optically identified and observed samples, especially when rare subclasses are considered or when subsets are isolated to search for evolution or correlations between wavebands. We describe the initial results of a new program aimed to ultimately yield ∼10 4 fully characterized X-ray source identifications - a sample about an order of magnitude larger than earlier efforts. The technique is detailed and employs X-ray data from the ROSAT All-Sky Survey (RASS) and optical imaging and spectroscopic follow-up from the Sloan Digital Sky Survey (SDSS); these two surveys prove to be serendipitously very well matched in sensitivity. As part of the SDSS software pipelines, optical objects in the SDSS photometric catalogs are automatically positionally cross-correlated with RASS X-ray sources. Then priorities for follow-on SDSS optical spectra of candidate counterparts are automatically assigned using an algorithm based on the known ratios of f x/f opt for various classes of X-ray emitters at typical RASS fluxes of ∼10 -13 ergs cm -2 s -1. SDSS photometric parameters for optical morphology, magnitude, and colors, plus FIRST radio information, serve as proxies for object class. Initial application of this approach to RASS/SDSS data from 1400 deg 2 of sky provides a catalog of more than 1200 spectroscopically confirmed quasars and other AGNs that are probable RASS identifications. Most of these are new identifications, and only a few percent of the AGN counterparts are likely to be random superpositions. The magnitude and redshift ranges of the counterparts are very broad, extending over 15 < m < 21 and 0.03 < z < 3.6, respectively. Although most identifications are quasars and Seyfert 1 galaxies, a variety of other AGN subclasses are also sampled. Substantial numbers of rare AGN types are found, including more than 130 narrow-line Seyfert 1 galaxies and 45 BL Lac candidates. These early results already provide a very sizable set of source identifications, demonstrate the utility of the sample in multiwaveband investigations, and show the capability of the joint RASS/SDSS approach to efficiently proceed toward the largest homogeneously selected/observed sample of X-ray-emitting quasars and other kinds of AGNs.

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