Accuracy of photometric redshifts for future weak lensing surveys from space

Abstract

Photometric redshifts are a key tool to extract as much information as possible from planned cosmic shear experiments. In this work we aim to test the performances that can be achieved with observations in the near-infrared from space and in the optical from the ground. This is done by performing realistic simulations of multi-band observations of a patch of the sky, and submitting these mock images to software usually applied to real images to extract the photometry and then a redshift estimate for each galaxy. In this way we mimic the most relevant sources of uncertainty present in real data analysis, including blending and light pollution between galaxies. As an example we adopt the infrared setup of the ESA-proposed Euclid mission, while we simulate different observations in the optical, modifying filters, exposure times and seeing values. Finally, we consider directly some future ground-based experiments, such as LSST, Pan-Starrs and DES. The results highlight the importance of u-band observations, especially to discriminate between low (z < 0.5) and high (z ~ 3) redshifts, and the need for good observing sites, with seeing FWHM < 1. arcsec. The former of these indications clearly favours the LSST experiment as a counterpart for space observations, while for the other experiments we need to exclude at least 15 % of the galaxies to reach a precision in the photo-zs equal to $<\frac{{\sigma }_z}{1+z}>$ < 0.05.

11 pages, to be published in MNRAS. Minor changes to match the published version

References in corpus (11)

• The Hubble Ultra Deep Field
• Galaxies in the Hubble Ultra Deep Field: I. Detection, Multiband Photometry, Photometric Redshifts, and Morphology
• The Zurich Extragalactic Bayesian Redshift Analyzer (ZEBRA) and its first application: COSMOS
• Photometric redshifts in the SWIRE Survey
• CARS: the CFHTLS-Archive-Research Survey; I. Five-band multi-colour data from 37 sq. deg. CFHTLS-Wide observations
• Evolution of the Color-Magnitude relation in High-Redshift Clusters: Early-type Galaxies in the Lynx Supercluster at z~1.26
• A Detailed Study of Photometric Redshifts for GOODS-South Galaxies
• Realistic simulations of gravitational lensing by galaxy clusters: extracting arc parameters from mock DUNE images
• A blind test of photometric redshifts on ground-based data
• Gravitational Lensing Accuracy Testing 2010 (GREAT10) Challenge Handbook
• Reliable Shapelet Image Analysis

Cited by in corpus (10)

• Redshift distributions of galaxies in the DES Science Verification shear catalogue and implications for weak lensing
• AMICO galaxy clusters in KiDS-DR3: weak-lensing mass calibration
• Multi-band morpho-Spectral Component Analysis Deblending Tool (MuSCADeT): Deblending colourful objects
• I. Apples to apples $A^2$: realistic galaxy simulated catalogs and photometric redshift predictions for next-generation surveys
• Weak Lensing Peaks in Simulated Light-Cones: Investigating the Coupling between Dark Matter and Dark Energy
• Predicting the number of giant arcs expected in the next generation wide-field surveys from space
• Extreme value statistics of weak lensing shear peak counts
• LineStacker: A spectral line stacking tool for interferometric data
• The intrinsic reddening of the Magellanic Clouds as traced by background galaxies -- III. The Large Magellanic Cloud
• Euclid preparation: Determining the weak lensing mass accuracy and precision for galaxy clusters