2010MNRAS.408.1283Z

Using the hyperz code and a template spectral library, which consists of four observed galaxy spectra from Coleman, Wu & Weedman (CWW) and eight spectral families built with evolutionary population synthesis models, we present photometric redshift (photo-z) estimates for a spectroscopic sample of 6531 galaxies. Spectroscopic redshifts are also available, and are selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and the Galaxy Evolution Explorer (GALEX) Data Release 4 (DR4). There are also morphologies for a morphological sample of 1502 bright galaxies, which are from the catalogue of Fukugita et al., and these are also matched with SDSS DR7 and GALEX DR4.

We find that the inclusion of F_UV or N_UV, or both, decreases the number of catastrophic identifications (|z_phot- z_spec| > 1.0). If catastrophic identifications are removed, the inclusion of both F_UV and N_UVphotometry mainly increases the number of non-catastrophic identifications in the low-redshift, and fainter r-magnitude regions. The inclusion of binary interactions mainly increases the number of non-catastrophic identifications and decreases the deviations in the region when only using optical photometry.

Based on the morphological galaxy sample, we find that the inclusion of ultraviolet (UV) photometry decreases and increases the probability that early types are classified as burst and E types, respectively. This increases the probability that late types are classified as CWW-Sbc and CWW-Scd types. If catastrophic identifications are excluded, the inclusion of UV data mainly increases the identifications of late types in all redshift, bluer g-r and r ≳ 14 regions. Moreover, binary interactions mainly affect the determinations of E and S0 types.

In comparison, we find that the reliability and completeness for early- and late-type selection by the hyperz code are less than those by the concentration index C = 2.6, the profile likelihood P_exp- P_deV= 0 and colour criteria. Moreover, we find that and discriminators can be used as morphology selection indicators. These two criteria have comparable reliability and completeness for selecting early- and late-type galaxies to C = 2.6 criterion and higher completeness for early-type selection than the criterion.