Active galactic nuclei in the sloan digital sky survey. I. Sample selection

Lei Hao, Michael A. Strauss, Christy A. Tremonti, David J. Schlegel, Timothy M. Heckman, Guinevere Kauffmann, Michael R. Blanton, Xiaohui Fan, James E. Gunn, Patrick B. Hall, Željko Ivezić, Gillian R. Knapp, Julian H. Krolik, Robert H. Lupton, Gordon T. Richards, Donald P. Schneider, Iskra V. Strateva, Nadia L. Zakamska, J. Brinkmann, Robert J. BrunnerGyula P. Szokoly

Research output: Contribution to journalReview article

182 Scopus citations

Abstract

We have compiled a large sample of low-redshift active galactic nuclei (AGNs) identified via their emission-line characteristics from the spectroscopic data of the Sloan Digital Sky Survey. Since emission lines are often contaminated by stellar absorption lines, we developed an objective and efficient method of subtracting the stellar continuum from every galaxy spectrum before making emission-line measurements. The distribution of the measured Hα FWHM values of emission-line galaxies is strongly bimodal, with two populations separated at about 1200 km s -1. This feature provides a natural separation between narrow-line and broad-line AGNs. The narrow-line AGNs are identified using standard emission-line ratio diagnostic diagrams. There are 1317 broad-line and 3074 narrow-line AGNs identified from about 100,000 galaxy spectra selected over 1151 deg 2. This sample is used in a companion paper to determine the emission-line luminosity function of AGNs.

Original languageEnglish (US)
Pages (from-to)1783-1794
Number of pages12
JournalAstronomical Journal
Volume129
Issue number4
DOIs
StatePublished - Apr 1 2005

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxies: activegalaxies: Seyfert
  • Galaxies: starburst
  • Quasars: emission linessurveys

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    Hao, L., Strauss, M. A., Tremonti, C. A., Schlegel, D. J., Heckman, T. M., Kauffmann, G., Blanton, M. R., Fan, X., Gunn, J. E., Hall, P. B., Ivezić, Ž., Knapp, G. R., Krolik, J. H., Lupton, R. H., Richards, G. T., Schneider, D. P., Strateva, I. V., Zakamska, N. L., Brinkmann, J., ... Szokoly, G. P. (2005). Active galactic nuclei in the sloan digital sky survey. I. Sample selection. Astronomical Journal, 129(4), 1783-1794. https://doi.org/10.1086/428485