Improved Photometric Redshifts with Surface Luminosity Priors
  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 6000-9000A, combined with
(U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ
redshifts is estimated to be \sigma (\Delta(z))=0.035 with an systematic offset
of -0.026, where \Delta(z)=\Delta z / (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 A 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
\Delta (z) > 0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the
fractional redshift error does not change much.
