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Accurate cosmic shear errors: do we need ensembles of simulations?

Barreira, Alexandre and Krause, Elisabeth and Schmidt, Fabian (2018) Accurate cosmic shear errors: do we need ensembles of simulations? Journal of Cosmology and Astroparticle Physics, 2018 (10). Art. No. 53. ISSN 1475-7516. doi:10.1088/1475-7516/2018/10/053.

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Accurate inference of cosmology from weak lensing shear requires an accurate shear power spectrum covariance matrix. Here, we investigate this accuracy requirement and quantify the relative importance of the Gaussian (G), super-sample covariance (SSC) and connected non-Gaussian (cNG) contributions to the covariance. Specifically, we forecast cosmological parameter constraints for future wide-field surveys and study how different covariance matrix components affect parameter bounds. Our main result is that the cNG term represents only a small and potentially negligible contribution to statistical parameter errors: the errors obtained using the G+SSC subset are within lesssim 5% of those obtained with the full G+SSC+cNG matrix for a Euclid-like survey. This result also holds for the shear two-point correlation function, variations in survey specifications and for different analytical prescriptions of the cNG term. The cNG term is that which is often tackled using numerically expensive ensembles of survey realizations. Our results suggest however that the accuracy of analytical or approximate numerical methods to compute the cNG term is likely to be sufficient for cosmic shear inference from the next generation of surveys.

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Additional Information:© 2018 IOP Publishing Ltd and Sissa Medialab. Received 30 July 2018. Accepted 17 October 2018. Published 29 October 2018. Some of the results in this paper were obtained using the Healpix package [78]. EK acknowledges support from NASA grant 15-WFIRST15-0008 Cosmology with the High Latitude Survey WFIRST Science Investigation Team. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. FS acknowledges support from the Starting Grant (ERC-2015-STG 678652) “GrInflaGal” of the European Research Council.
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European Research Council (ERC)678652
Issue or Number:10
Record Number:CaltechAUTHORS:20181029-094837932
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Official Citation:Alexandre Barreira et al JCAP10(2018)053
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90450
Deposited By: George Porter
Deposited On:29 Oct 2018 18:29
Last Modified:12 Jul 2022 17:35

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