Average spectra of massive galaxies in the Sloan Digital Sky Survey

Daniel J. Eisenstein*, David W. Hogg, Masataka Fukugita, Osamu Nakamura, Mariangela Bernardi, Douglas P. Finkbeiner, David J. Schlegel, J. Brinkmann, Andrew J. Connolly, István Csabai, James E. Gunn, Željko Ivezić, Don Q. Lamb, Jon Loveday, Jeffrey A. Munn, Robert C. Nicol, Donald P. Schneider, Michael A. Strauss, Alex Szalay, Don G. York

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

88 Citations (Scopus)


We combine Sloan Digital Sky Survey spectra of 22,000 luminous, red, bulge-dominated galaxies to get high signal-to-noise ratio average spectra in the rest-frame optical and ultraviolet (2600-7000 A). The average spectra of these massive, quiescent galaxies are early type with weak emission lines and with absorption lines indicating an apparent excess of α-elements over solar abundance ratios. We make average spectra of subsamples selected by luminosity, environment, and redshift. The average spectra are remarkable in their similarity. What variations do exist in the average spectra as a function of luminosity and environment are found to form a nearly one-parameter family in spectrum space. We present a high signal-to-noise ratio spectrum of the variation. We measure the properties of the variation with a modified version of the Lick index system and compare to model spectra from stellar population syntheses. The variation may be a combination of age and chemical abundance differences, but the conservative conclusion is that the quality of the data considerably exceeds the current state of the models.

Original languageEnglish
Pages (from-to)694-713
Number of pages20
JournalAstrophysical Journal
Issue number2 I
Publication statusPublished - 2003 Mar 10
Externally publishedYes


  • Cosmology: observations
  • Galaxies: abundances
  • Galaxies: clusters: general
  • Galaxies: elliptical and lenticular, cD
  • Galaxies: evolution
  • Methods: statistical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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