Creating spectral templates from multicolor redshift surveys

Tamás Budavári, Alexander S. Szalay, Andrew J. Connolly, István Csabai, Mark Dickinson

Research output: Contribution to journalReview article

95 Citations (Scopus)


Understanding how the physical properties of galaxies (e.g., their spectral type or age) evolve as a function of redshift relies on having an accurate representation of galaxy spectral energy distributions. While it has been known for some time that galaxy spectra can be reconstructed from a handful of orthogonal basis templates, the underlying basis is poorly constrained. The limiting factor has been the lack of large samples of galaxies (covering a wide range in spectral type) with high signal-to-noise spectrophotometric observations. To alleviate this problem we introduce here a new technique for reconstructing galaxy spectral energy distributions directly from samples of galaxies with broadband photometric data and spectroscopic redshifts. Exploiting the statistical approach of the Karhunen-Loève expansion, our iterative training procedure increasingly improves the eigenbasis, so that it provides better agreement with the photometry. We demonstrate the utility of this approach by applying these improved spectral energy distributions to the estimation of photometric redshifts for the HDF sample of galaxies. We find that in a small number of iterations the dispersion in the photometric redshifts estimator (a comparison between predicted and measured redshifts) can decrease by up to a factor of 2.

Original languageEnglish
Pages (from-to)1588-1598
Number of pages11
JournalAstronomical Journal
Issue number3
Publication statusPublished - Sep 2000


  • Galaxies: distances and redshifts
  • Galaxies: photometry

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Budavári, T., Szalay, A. S., Connolly, A. J., Csabai, I., & Dickinson, M. (2000). Creating spectral templates from multicolor redshift surveys. Astronomical Journal, 120(3), 1588-1598.