Designing future dark energy space missions

Abstract

Context. Future dark energy space missions such as JDEM and EUCLID are being designed to survey the galaxy population to trace the geometry of the universe and the growth of structure, which both depend on the cosmological model. To reach the goal of high precision cosmology they need to evaluate the capabilities of different instrument designs based on realistic mock catalogs of the galaxy distribution. Aims. The aim of this paper is to construct realistic and flexible mock catalogs based on our knowledge of galaxy populations from current deep surveys. We explore two categories of mock catalogs: (i) based on luminosity functions that we fit to observations (GOODS, UDF, COSMOS, VVDS); (ii) based on the observed COSMOS galaxy distribution. Methods. The COSMOS mock catalog benefits from all the properties of the data-rich COSMOS survey and the highly accurate photometric redshift distribution based on 30-band photometry. Nevertheless this catalog is limited by the depth of the COSMOS survey. Thus, we also evaluate a mock galaxy catalog generated from luminosity functions using the Le Phare software. For these two catalogs, we have produced simulated number counts in several bands, color diagrams and redshift distributions for validation against real observational data. Results. Using these mock catalogs we derive some basic requirements to help design future Dark Energy missions in terms of the number of galaxies available for the weak-lensing analysis as a function of the PSF size and depth of the survey. We also compute the spectroscopic success rate for future spectroscopic redshift surveys (i) aiming at measuring BAO in the case of the wide field spectroscopic redshift survey, and (ii) for the photometric redshift calibration survey which is required to achieve weak lensing tomography with great accuracy. In particular, we demonstrate that for the photometric redshift calibration, using only NIR (1-1.7 μm) spectroscopy, we cannot achieve a complete spectroscopic survey down to the limit of the photometric survey (I < 25.5). Extending the wavelength coverage of the spectroscopic survey to cover 0.6-1.7 μm will then improve the fraction of very secure spectroscopic redshifts to nearly 80% of the galaxies, making possible a very accurate photometric redshift calibration. Conclusions. We have produced two realistic mock galaxy catalogs that can be used in determining the best survey strategy for future dark-energy missions in terms of photometric redshift accuracy and spectroscopic redshift surveys yield. These catalogues are publicly accessible at http://lamwws.oamp.fr/cosmowiki/RealisticSpectroPhotCat, or at the CDS.

The 0.1 <z< 1.65 evolution of the bright end of the [O ii] luminosity function

“…It was designed using the Cosmos Mock Catalog (Jouvel et al 2009); -Class B: Herschel detected galaxies at 5σ (Lutz et al 2011); -Class C: MIPS detected galaxies at 5σ (Le Floc'h et al 2009); -Class D: ugr selection from Comparat et al (2013b;20 < g < 23.5, −0.5 < u − g < 1, −1 < g − r < 1, −0.5 < u − r < 0.5); -Class E: gri selection from Comparat et al (2013b;−0.1 < g − r < 1.1, 0.8 < r − i < 1.4, 20.5 < i < 23.5); -Class F: a photometric redshift selection 1 < z phot < 1.7 and 20 < i < 24 to fill the remaining empty area of the masks.…”

Non-negative Matrix Factorization for Self-calibration of Photometric Redshift Scatter in Weak-lensing Surveys

“…The fiducial scatters are obtained based on the simulated data from Bernstein & Huterer (2010), which is produced for a SNAP-like survey using the method described in Jouvel et al (2009) . Fig.…”

Modeling the Transfer Function for the Dark Energy Survey

“…36 The apparent magnitude of stars and galaxies, as well as the ellipticity of galaxies are taken directly from the BCC catalogs. The intrinsic galaxy size information is based on the BCC catalogs but adjusted slightly so that the 2d distribution in apparent magnitude and intrinsic size is consistent with that derived from the COSMOS data (Jouvel et al 2009). The adjustment is needed because the BCC catalog takes an approximate approach when converting the observed galaxy size into the intrinsic galaxy size.…”