TY - JOUR
T1 - Improved photometric redshifts with surface luminosity priors
AU - Xia, Lifang
AU - Cohen, Seth
AU - Malhotra, Sangeeta
AU - Rhoads, James
AU - Grogin, Norman
AU - Hathi, Nimish P.
AU - Windhorst, Rogier
AU - Pirzkal, Nor
AU - Xu, Chun
PY - 2009
Y1 - 2009
N2 - 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.
AB - 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.
KW - Galaxies: distances and redshifts
KW - Galaxies: photometry
KW - Methods: statistical
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U2 - 10.1088/0004-6256/138/1/95
DO - 10.1088/0004-6256/138/1/95
M3 - Article
AN - SCOPUS:67749093208
SN - 0004-6256
VL - 138
SP - 95
EP - 101
JO - Astronomical Journal
JF - Astronomical Journal
IS - 1
ER -