2015/05/05 by N. Greisel, Greisel, N., S. Seitz +10
Chemistry · Mathematics · Physics and Astronomy · #Advanced Statistical Methods and Models #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Spectroscopy and Chemometric Analyses #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.1505.01157
24 pages, 29 figures, accepted for publication in the MNRAS
openalex publication_date 2015/05/05 · arxiv created 2015/05/07 · arxiv updated 2015/05/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We construct a set of model spectra specifically designed to match the colours of the BOSS CMASS galaxies and to be used with photometric redshift template fitting techniques. As a basis we use a set of spectral energy distributions (SEDs) of single and composite stellar population models. These models cannot describe well the whole colour range populated by the CMASS galaxies at all redshifts, wherefore we modify them by multiplying the SEDs with λ-β for λ>λi for different values of λi and β. When fitting these SEDs to the colours of the CMASS sample, with a burst and dust components in superposition, we can recreate the location in colour spaces inhabited by the CMASS galaxies. From the best fitting models we select a small subset in a two-dimensional plane, whereto the galaxies were mapped by a self-organizing map. These models are used for the estimation of photometric redshifts with a Bayesian template fitting code. The photometric redshifts with the novel templates have a very small outlier rate of 0.22 %, a low bias ⟨Δz/(1+z)⟩=2.0⋅10-3, and scatter of σ68=0.026 in the restframe. Using our models, the galaxy colours are reproduced to a better extent with the photometric redshifts of this work than with photometric redshifts of SDSS.