Improved photometric redshifts with surface luminosity priors

Lifang Xia, Seth Cohen, Sangeeta Malhotra, James Rhoads, Norman Grogin, Nimish P. Hathi, Rogier Windhorst, Nor Pirzkal, Chun Xu

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at 0.1 ≲ z ≲ 2.0. We start with spectrophotometric redshifts (SPZs) based on Probing Evolution and Reionization Spectroscopically grism spectra, which cover a wavelength range of 6000-9000 , combined with (U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ redshifts is estimated to be σ(Δ(z)) = 0.035 with an systematic offset of -0.026, where Δ(z) = Δz/(1 + z), for galaxies in redshift range of 0.5 ≲ z ≲ 1.25. The addition of the SL prior probability helps break the degeneracy of SPZ redshifts between low redshift 4000 break galaxies and high-redshift Lyman break galaxies which are mostly catastrophic outliers. For the 1138 galaxies at z ≲ 1.6, the fraction of galaxies with redshift deviation Δ(z)>0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the fractional redshift error does not change much.

Original languageEnglish (US)
Pages (from-to)95-101
Number of pages7
JournalAstronomical Journal
Issue number1
StatePublished - 2009


  • Galaxies: distances and redshifts
  • Galaxies: photometry
  • Methods: statistical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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