TY - JOUR
T1 - Calibrating photometric redshifts of luminous red galaxies
AU - Padmanabhan, Nikhil
AU - Budavári, Tamás
AU - Schlegel, David J.
AU - Bridges, Terry
AU - Brinkmann, Jonathan
AU - Cannon, Russell
AU - Connolly, Andrew J.
AU - Croom, Scott M.
AU - Csabai, István
AU - Drinkwater, Michael
AU - Eisenstein, Daniel J.
AU - Hewett, Paul C.
AU - Loveday, Jon
AU - Nichol, Robert C.
AU - Pimbblet, Kevin A.
AU - De Propris, Roberto
AU - Schneider, Donald P.
AU - Scranton, Ryan
AU - Seljak, Uroš
AU - Shanks, Tom
AU - Szapudi, István
AU - Szalay, Alexander S.
AU - Wake, David
PY - 2005/5/1
Y1 - 2005/5/1
N2 - We discuss the construction of a photometric redshift catalogue of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue: (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, and (iii) estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS-2dF (Two Degree Field) spectroscopic surveys, we find that the photometric redshift accuracy is σ ∼ 0.03 for redshifts less than 0.55 and worsens at higher redshift (∼ 0.06 for z < 0.7). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves and photometric zero-points. We also parametrize the photometric redshift error distribution with a sum of Gaussians and use this model to deconvolve the errors from the measured photometric redshift distribution to estimate the true redshift distribution. We pay special attention to the stability of this deconvolution, regularizing the method with a prior on the smoothness of the true redshift distribution. The methods that we develop are applicable to general photometric redshift surveys.
AB - We discuss the construction of a photometric redshift catalogue of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue: (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, and (iii) estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS-2dF (Two Degree Field) spectroscopic surveys, we find that the photometric redshift accuracy is σ ∼ 0.03 for redshifts less than 0.55 and worsens at higher redshift (∼ 0.06 for z < 0.7). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves and photometric zero-points. We also parametrize the photometric redshift error distribution with a sum of Gaussians and use this model to deconvolve the errors from the measured photometric redshift distribution to estimate the true redshift distribution. We pay special attention to the stability of this deconvolution, regularizing the method with a prior on the smoothness of the true redshift distribution. The methods that we develop are applicable to general photometric redshift surveys.
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U2 - 10.1111/j.1365-2966.2005.08915.x
DO - 10.1111/j.1365-2966.2005.08915.x
M3 - Article
AN - SCOPUS:18444379098
SN - 0035-8711
VL - 359
SP - 237
EP - 250
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -