Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey

Željko Ivezíc, Kristen Menou, Gillian R. Knapp, Michael A. Strauss, Robert H. Lupton, Daniel E. Vanden Berk, Gordon T. Richards, Christy Tremonti, Michael A. Weinstein, Scott Anderson, Neta A. Bahcall, Robert H. Becker, Mariangela Bernardi, Michael Blanton, Daniel Eisenstein, Xiaohui Fan, Douglas Finkbeiner, Kristian Finlator, Joshua Frieman, James E. GunnPat B. Hall, Rita S J Kim, Ali Kinkhabwala, Vijay K. Narayanan, Constance M. Rockosi, David Schlegel, Donald P. Schneider, Iskra Strateva, Mark Subbarao, Aniruddha R. Thakar, Wolfgang Voges, Rlchard L. White, Brian Yanny, Jonathan Brinkmann, Mamoru Doi, Masataka Fukugita, Gregory S. Hennessy, Jeffrey A. Munn, Robert C. Nichol, Donald G. York

Research output: Contribution to journalArticle

332 Citations (Scopus)

Abstract

We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1.″5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r* ∼ 22.2) source in 1230 deg2 of sky. The matched sample represents ∼ 30% of the 108,000 FIRST sources and 0.1% of the 2.5 × 10 7 SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20,000 quasars in 1030 deg2 of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10%. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83%) of the FIRST sources identified with an SDSS source brighter than r* = 21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from ∼50% at the bright end to ∼90% at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of ∼5% for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux-optical flux plane suggests the existence of the "quasar radio dichotomy"; 8% ± 1% of all quasars with i* < 18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08 ± 0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5% of all SDSS galaxies with r* < 17.5, and 1% for r* < 20, and are dominated by red (u* - r* > 2.22) galaxies, especially those with r* > 17.5. Magnitude-and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN (30%), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r* < 17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.

Original languageEnglish (US)
Pages (from-to)2364-2400
Number of pages37
JournalAstronomical Journal
Volume124
Issue number5 1763
DOIs
StatePublished - Nov 2002
Externally publishedYes

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quasars
radio
galaxies
optical properties
radio galaxies
color
starburst galaxies
luminosity
radio emission
sky
dichotomies
catalogs
broadband
footing
stars
causes
estimates

Keywords

  • Galaxies: active
  • Galaxies: photometry
  • Quasars: general
  • Radio continuum

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Ivezíc, Ž., Menou, K., Knapp, G. R., Strauss, M. A., Lupton, R. H., Vanden Berk, D. E., ... York, D. G. (2002). Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey. Astronomical Journal, 124(5 1763), 2364-2400. https://doi.org/10.1086/344069

Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey. / Ivezíc, Željko; Menou, Kristen; Knapp, Gillian R.; Strauss, Michael A.; Lupton, Robert H.; Vanden Berk, Daniel E.; Richards, Gordon T.; Tremonti, Christy; Weinstein, Michael A.; Anderson, Scott; Bahcall, Neta A.; Becker, Robert H.; Bernardi, Mariangela; Blanton, Michael; Eisenstein, Daniel; Fan, Xiaohui; Finkbeiner, Douglas; Finlator, Kristian; Frieman, Joshua; Gunn, James E.; Hall, Pat B.; Kim, Rita S J; Kinkhabwala, Ali; Narayanan, Vijay K.; Rockosi, Constance M.; Schlegel, David; Schneider, Donald P.; Strateva, Iskra; Subbarao, Mark; Thakar, Aniruddha R.; Voges, Wolfgang; White, Rlchard L.; Yanny, Brian; Brinkmann, Jonathan; Doi, Mamoru; Fukugita, Masataka; Hennessy, Gregory S.; Munn, Jeffrey A.; Nichol, Robert C.; York, Donald G.

In: Astronomical Journal, Vol. 124, No. 5 1763, 11.2002, p. 2364-2400.

Research output: Contribution to journalArticle

Ivezíc, Ž, Menou, K, Knapp, GR, Strauss, MA, Lupton, RH, Vanden Berk, DE, Richards, GT, Tremonti, C, Weinstein, MA, Anderson, S, Bahcall, NA, Becker, RH, Bernardi, M, Blanton, M, Eisenstein, D, Fan, X, Finkbeiner, D, Finlator, K, Frieman, J, Gunn, JE, Hall, PB, Kim, RSJ, Kinkhabwala, A, Narayanan, VK, Rockosi, CM, Schlegel, D, Schneider, DP, Strateva, I, Subbarao, M, Thakar, AR, Voges, W, White, RL, Yanny, B, Brinkmann, J, Doi, M, Fukugita, M, Hennessy, GS, Munn, JA, Nichol, RC & York, DG 2002, 'Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey', Astronomical Journal, vol. 124, no. 5 1763, pp. 2364-2400. https://doi.org/10.1086/344069
Ivezíc Ž, Menou K, Knapp GR, Strauss MA, Lupton RH, Vanden Berk DE et al. Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey. Astronomical Journal. 2002 Nov;124(5 1763):2364-2400. https://doi.org/10.1086/344069
Ivezíc, Željko ; Menou, Kristen ; Knapp, Gillian R. ; Strauss, Michael A. ; Lupton, Robert H. ; Vanden Berk, Daniel E. ; Richards, Gordon T. ; Tremonti, Christy ; Weinstein, Michael A. ; Anderson, Scott ; Bahcall, Neta A. ; Becker, Robert H. ; Bernardi, Mariangela ; Blanton, Michael ; Eisenstein, Daniel ; Fan, Xiaohui ; Finkbeiner, Douglas ; Finlator, Kristian ; Frieman, Joshua ; Gunn, James E. ; Hall, Pat B. ; Kim, Rita S J ; Kinkhabwala, Ali ; Narayanan, Vijay K. ; Rockosi, Constance M. ; Schlegel, David ; Schneider, Donald P. ; Strateva, Iskra ; Subbarao, Mark ; Thakar, Aniruddha R. ; Voges, Wolfgang ; White, Rlchard L. ; Yanny, Brian ; Brinkmann, Jonathan ; Doi, Mamoru ; Fukugita, Masataka ; Hennessy, Gregory S. ; Munn, Jeffrey A. ; Nichol, Robert C. ; York, Donald G. / Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey. In: Astronomical Journal. 2002 ; Vol. 124, No. 5 1763. pp. 2364-2400.
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title = "Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey",
abstract = "We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1.″5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r* ∼ 22.2) source in 1230 deg2 of sky. The matched sample represents ∼ 30{\%} of the 108,000 FIRST sources and 0.1{\%} of the 2.5 × 10 7 SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20,000 quasars in 1030 deg2 of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10{\%}. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83{\%}) of the FIRST sources identified with an SDSS source brighter than r* = 21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from ∼50{\%} at the bright end to ∼90{\%} at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of ∼5{\%} for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux-optical flux plane suggests the existence of the {"}quasar radio dichotomy{"}; 8{\%} ± 1{\%} of all quasars with i* < 18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08 ± 0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5{\%} of all SDSS galaxies with r* < 17.5, and 1{\%} for r* < 20, and are dominated by red (u* - r* > 2.22) galaxies, especially those with r* > 17.5. Magnitude-and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN (30{\%}), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r* < 17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.",
keywords = "Galaxies: active, Galaxies: photometry, Quasars: general, Radio continuum",
author = "Željko Ivez{\'i}c and Kristen Menou and Knapp, {Gillian R.} and Strauss, {Michael A.} and Lupton, {Robert H.} and {Vanden Berk}, {Daniel E.} and Richards, {Gordon T.} and Christy Tremonti and Weinstein, {Michael A.} and Scott Anderson and Bahcall, {Neta A.} and Becker, {Robert H.} and Mariangela Bernardi and Michael Blanton and Daniel Eisenstein and Xiaohui Fan and Douglas Finkbeiner and Kristian Finlator and Joshua Frieman and Gunn, {James E.} and Hall, {Pat B.} and Kim, {Rita S J} and Ali Kinkhabwala and Narayanan, {Vijay K.} and Rockosi, {Constance M.} and David Schlegel and Schneider, {Donald P.} and Iskra Strateva and Mark Subbarao and Thakar, {Aniruddha R.} and Wolfgang Voges and White, {Rlchard L.} and Brian Yanny and Jonathan Brinkmann and Mamoru Doi and Masataka Fukugita and Hennessy, {Gregory S.} and Munn, {Jeffrey A.} and Nichol, {Robert C.} and York, {Donald G.}",
year = "2002",
month = "11",
doi = "10.1086/344069",
language = "English (US)",
volume = "124",
pages = "2364--2400",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "5 1763",

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TY - JOUR

T1 - Optical and radio properties of extragalactic sources observed by the first survey and the sloan digital sky survey

AU - Ivezíc, Željko

AU - Menou, Kristen

AU - Knapp, Gillian R.

AU - Strauss, Michael A.

AU - Lupton, Robert H.

AU - Vanden Berk, Daniel E.

AU - Richards, Gordon T.

AU - Tremonti, Christy

AU - Weinstein, Michael A.

AU - Anderson, Scott

AU - Bahcall, Neta A.

AU - Becker, Robert H.

AU - Bernardi, Mariangela

AU - Blanton, Michael

AU - Eisenstein, Daniel

AU - Fan, Xiaohui

AU - Finkbeiner, Douglas

AU - Finlator, Kristian

AU - Frieman, Joshua

AU - Gunn, James E.

AU - Hall, Pat B.

AU - Kim, Rita S J

AU - Kinkhabwala, Ali

AU - Narayanan, Vijay K.

AU - Rockosi, Constance M.

AU - Schlegel, David

AU - Schneider, Donald P.

AU - Strateva, Iskra

AU - Subbarao, Mark

AU - Thakar, Aniruddha R.

AU - Voges, Wolfgang

AU - White, Rlchard L.

AU - Yanny, Brian

AU - Brinkmann, Jonathan

AU - Doi, Mamoru

AU - Fukugita, Masataka

AU - Hennessy, Gregory S.

AU - Munn, Jeffrey A.

AU - Nichol, Robert C.

AU - York, Donald G.

PY - 2002/11

Y1 - 2002/11

N2 - We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1.″5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r* ∼ 22.2) source in 1230 deg2 of sky. The matched sample represents ∼ 30% of the 108,000 FIRST sources and 0.1% of the 2.5 × 10 7 SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20,000 quasars in 1030 deg2 of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10%. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83%) of the FIRST sources identified with an SDSS source brighter than r* = 21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from ∼50% at the bright end to ∼90% at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of ∼5% for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux-optical flux plane suggests the existence of the "quasar radio dichotomy"; 8% ± 1% of all quasars with i* < 18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08 ± 0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5% of all SDSS galaxies with r* < 17.5, and 1% for r* < 20, and are dominated by red (u* - r* > 2.22) galaxies, especially those with r* > 17.5. Magnitude-and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN (30%), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r* < 17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.

AB - We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1.″5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r* ∼ 22.2) source in 1230 deg2 of sky. The matched sample represents ∼ 30% of the 108,000 FIRST sources and 0.1% of the 2.5 × 10 7 SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20,000 quasars in 1030 deg2 of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10%. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83%) of the FIRST sources identified with an SDSS source brighter than r* = 21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from ∼50% at the bright end to ∼90% at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of ∼5% for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux-optical flux plane suggests the existence of the "quasar radio dichotomy"; 8% ± 1% of all quasars with i* < 18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08 ± 0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5% of all SDSS galaxies with r* < 17.5, and 1% for r* < 20, and are dominated by red (u* - r* > 2.22) galaxies, especially those with r* > 17.5. Magnitude-and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN (30%), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r* < 17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.

KW - Galaxies: active

KW - Galaxies: photometry

KW - Quasars: general

KW - Radio continuum

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