CosmoLike - Cosmological Likelihood Analyses for Photometric Galaxy Surveys

TL;DR

This paper evaluates strategies for extracting cosmological information from joint analyses of multiple galaxy survey probes using the CosmoLike software, emphasizing the importance of small scales and systematics modeling.

Contribution

It introduces a comprehensive multi-probe analysis framework with detailed modeling of systematics and explores the impact of survey choices and scales on cosmological constraints.

Findings

Increasing source galaxy density yields limited gains.

Including small scales significantly improves constraints.

Proper modeling of systematics is crucial for accurate results.

Abstract

We explore strategies to extract cosmological constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, galaxy clustering, cluster number counts and cluster weak lensing. We utilize the CosmoLike software to simulate results from an LSST like data set, specifically, we 1) compare individual and joint analyses of the different probes, 2) vary the selection criteria for lens and source galaxies, 3) investigate the impact of blending, 4) investigate the impact of the assumed cosmological model in multi-probe covariances, 6) quantify information content as a function of scales, and 7) explore the impact of intrinsic galaxy alignment in a multi-probe context. Our analyses account for all cross correlations within and across probes and include the higher-order (non-Gaussian) terms in the multi-probe covariance matrix. We simultaneously model cosmological parameters and a variety of systematics, e.g. uncertainties arising from shear and photo-z calibration, cluster mass-observable relation, galaxy intrinsic alignment, and galaxy bias (up to 54 parameters altogether). We highlight two results: First, increasing the number density of source galaxies by ~30%, which corresponds to solving blending for LSST, only gains little information. Second, including small scales in clustering and galaxy-galaxy lensing, by utilizing HODs, can substantially boost cosmological constraining power. The CosmoLike modules used to compute the results in this paper will be made publicly available at https://github.com/elikrause/CosmoLike_Forecasts.