Calibrating photometric redshifts of luminous red galaxies
Authors: Padmanabhan, Nikhil; Budavári, Tamás1; Schlegel, David J.2; Bridges, Terry3; Brinkmann, Jonathan4; Cannon, Russell5; Connolly, Andrew J.6; Croom, Scott M.5; Csabai, István7; Drinkwater, Michael8; Eisenstein, Daniel J.9; Hewett, Paul C.10; Loveday, Jon11; Nichol, Robert C.12; Pimbblet, Kevin A.8; De Propris, Roberto13; Schneider, Donald P.14; Scranton, Ryan6; Seljak, Uroš15; Shanks, Tom16; Szapudi, István17; Szalay, Alexander S.1; Wake, David18
Source: Monthly Notices of the Royal Astronomical Society, Volume 359, Number 1, May 2005 , pp. 237-250(14)
Publisher: Blackwell Publishing
- Free Content
- New Content
- Subscribed Content
- Free Trial Content
Abstract:
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.Keywords: catalogues; surveys; galaxies: fundamental parameters
Document Type: Research article
DOI: 10.1111/j.1365-2966.2005.08915.x
Affiliations: 1: Center for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA 2: Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA 3: Physics Department, Queen's University, Kingston, ON, Canada, K7M 3N6 4: Apache Point Observatory, 2001 Apache Point Road, Sunspot, NM 88349-0059, USA 5: Anglo-Australian Observatory, PO Box 296, Epping, NSW 2121, Australia 6: Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA 7: Department of Physics, Eötvös University, Budapest, Pf. 32, Hungary, H-1518 8: Department of Physics, University of Queensland, Qld 4072, Australia 9: Steward Observatory, 933 N. Cherry Ave, Tucson, AZ 85721, USA 10: Institute of Astronomy, Madingley Road, Cambridge CB3 0HA 11: Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QJ 12: Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG 13: Research School of Astronomy and Astrophysics, Australian National University, Weston, ACT 2611, Australia 14: Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA 15: Joseph Henry Laboratories, Jadwin Hall, Princeton University, Princeton, NJ 08544, USA 16: Department of Physics, University of Durham, South Road, Durham DH1 3LE 17: Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA 18: Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA
- Free Content
- New Content
- Subscribed Content
- Free Trial Content
Click here for Page Help