2009/10/31 by Pengjie Zhang, Ue-Li Pen, Ue‐Li Pen +2
Mathematics · Physics and Astronomy · #Adaptive optics and wavefront sensing #Astrophysics #Calibration #Cosmology #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational lens #Outlier #Photometric redshift #Physics #Redshift #Statistical and numerical algorithms #Statistics #Weak gravitational lensing #astro-ph.CO
paper · pdf · doi:10.1111/j.1365-2966.2010.16445.x
published as Mon.Not.Roy.Astron.Soc.405:359,2010 · v2: 19 pages, 10 figures. Added one figure. Expanded discussions. Accepted to MNRAS
arxiv created 2010/02/03 · openalex publication_date 2010/03/01 · arxiv updated 2015/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Photometric redshift (photo-z) errors, especially catastrophic errors, are a major uncertainty for precision weak-lensing cosmology. We find that the shear (galaxy number) density and density–density cross-correlation measurements between photo-z bins, available from the same lensing surveys, contain valuable information for self-calibration of the scattering probabilities between the true redshift and photo-z bins. The self-calibration technique we propose does not rely on cosmological priors nor parameterization of the photo-z probability distribution function, and preserves all of the cosmological information available from shear–shear measurement. We estimate the calibration accuracy through the Fisher matrix formalism. We find that, for advanced lensing surveys such as the planned Stage IV surveys, the rate of photo-z outliers can be determined with statistical uncertainties of 0.01–1 per cent for z < 2 galaxies. Among the several sources of calibration error that we identify and investigate, the galaxy distribution bias is likely the most dominant systematic error, whereby photo-z outliers have different redshift distributions and/or bias than non-outliers from the same bin. This bias affects all photo-z calibration techniques based on correlation measurements. Galaxy bias variations of O(0.1) produce biases in photo-z outlier rates similar to the statistical errors of our method, so this galaxy distribution bias may bias the reconstructed scatters at several-σ level, but is unlikely to completely invalidate the self-calibration technique.