Tomas Dahlen et al. 2008 The Astronomical Journal 136 1361 doi:10.1088/0004-6256/136/3/1361
Tomas Dahlen1, Bahram Mobasher1, Stephanie Jouvel2, Jean-Paul Kneib2, Olivier Ilbert2, Stephane Arnouts2, Gary Bernstein3 and Jason Rhodes4,5
Show affiliationsThe aim of this paper is to investigate ways to optimize the accuracy of photometric redshifts for a Supernova Acceleration Probe (SNAP)-like mission. We focus on how the accuracy of the photometric redshifts depends on the magnitude limit and signal-to-noise ratio (S/N), wavelength coverage, and the number of filters and their shapes and observed galaxy type. We use simulated galaxy catalogs constructed to reproduce observed galaxy luminosity functions from the Great Observatories Origins Deep Survey and derive photometric redshifts using a template fitting method. By using a catalog that resembles real data, we can estimate the expected number density of galaxies for which photometric redshifts can be derived. We find that the accuracy of the photometric redshifts is strongly dependent on the S/N (i.e., S/N > 10 is needed for accurate photometric redshifts). The accuracy of the photometric redshifts is also dependent on galaxy type, with smaller scatter for earlier-type galaxies. Comparing results using different filter sets, we find that including the U-band and near-IR bands is important for decreasing the fraction of outliers, i.e., "catastrophic failures." Using broad overlapping filters with resolution ~4 gives better photometric redshifts compared to narrower filters (resolution
5) with the same integration time. We find that filters with square response curves result in a slightly higher scatter, mainly due to a higher fraction of outliers at faint magnitudes. We also compare a 9-filter set to a 17-filter set, where we assume that the available exposure time per filter in the latter set is half that of the first set. We find that the 9-filter set gives more accurate redshifts for a larger number of objects and reaches higher redshift, while the 17-filter set gives better results at bright magnitudes.
Issue 3 (2008 September)
Received 2007 October 22, accepted for publication 2008 June 30
Published 2008 August 15
Tomas Dahlen et al. 2008 The Astronomical Journal 136 1361
Gary M. Bernstein 2009 ApJ 695 652
Zhaoming Ma and Gary Bernstein 2008 ApJ 682 39
N. Perra et al 2009 EPL 88 48002
A Richter 2006 Phys. Scr. 2006 167
A Richter 2005 J. Phys.: Conf. Ser. 20 13
Jie Yang et al 2008 Supercond. Sci. Technol. 21 082001
Alessandro Magni et al J. Stat. Mech. (2009) P01020
Zénó Farkas et al 2003 J. Phys.: Condens. Matter 15 S1767
Kurusch Ebrahimi-Fard and Dirk Kreimer 2005 J. Phys. A: Math. Gen. 38 R385