2008/12/18 by N. Benitez, N. Benı́tez, M. Moles +32 · 92 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Astrophysics #Computer science #Computer vision #Filter (signal processing) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Photometric redshift #Photometric system #Photometry (optics) #Physics #Redshift #Stars #Telescope #astro-ph
paper · pdf · doi:10.1088/0004-637x/692/1/l5
published in The Astrophysical Journal 692(1), L5-L8 (IOP Publishing) · 4 pages, 4 figures, to appear in The Astrophysical Journal Letters
arxiv created 2008/12/18 · openalex publication_date 2009/01/21 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
In the coming years, several cosmological surveys will rely on imaging data to estimate the redshift of galaxies, using traditional filter systems with 4–5 optical broad bands; narrower filters improve the spectral resolution, but strongly reduce the total system throughput. We explore how photometric redshift performance depends on the number of filters n f , characterizing the survey depth by the fraction of galaxies with unambiguous redshift estimates. For a combination of total exposure time and telescope imaging area of 270 hr m 2 , 4–5 filter systems perform significantly worse, both in completeness depth and precision, than systems with n f ≳ 8 filters. Our results suggest that for low n f the color–redshift degeneracies overwhelm the improvements in photometric depth, and that even at higher n f the effective photometric redshift depth decreases much more slowly with filter width than naively expected from the reduction in the signal-to-noise ratio. Adding near-IR observations improves the performance of low- n f systems, but still the system which maximizes the photometric redshift completeness is formed by nine filters with logarithmically increasing bandwidth (constant resolution) and half-band overlap, reaching ∼0.7 mag deeper, with 10% better redshift precision, than 4–5 filter systems. A system with 20 constant-width, nonoverlapping filters reaches only ∼0.1 mag shallower than 4–5 filter systems, but has a precision almost three times better, δ z = 0.014(1 + z ) versus δ z = 0.042(1 + z ). We briefly discuss a practical implementation of such a photometric system: the ALHAMBRA Survey.