de la Bella, LF;
Tessore, N;
Bridle, S;
(2021)
The unequal-time matter power spectrum: impact on weak lensing observables.
Journal of Cosmology and Astroparticle Physics
, 2021
(8)
10.1088/1475-7516/2021/08/001.
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Abstract
We investigate the impact of a common approximation of weak lensing power spectra: the use of single-epoch matter power spectra in integrals over redshift. We disentangle this from the closely connected Limber’s approximation. We derive the unequal-time matter power spectrum at one-loop in standard perturbation theory and effective field theory to deal with non-linear physics. We compare these formalisms and conclude that the unequaltime power spectrum using effective field theory breaks for larger scales. As an alternative we introduce the midpoint approximation. We also provide, for the first time, a fitting function for the time evolution of the effective field theory counterterms based on the Quijote simulations. Then we compute the angular power spectrum using a range of approaches: the Limber approximation, and the geometric and midpoint approximations. We compare our results with the exact calculation at all angular scales using the unequal-time power spectrum. We use DES Y1 and LSST-like redshift distributions for our analysis. We find that the use of the Limber’s approximation in weak lensing diverges from the exact calculation of the angular power spectrum on large-angle separations, ` < 10. Even though this deviation is of order 2% maximum for cosmic lensing, we find the biggest effect for galaxy clustering and galaxy-galaxy lensing. We show that not only is this true for upcoming galaxy surveys, but also for current data such as DES Y1. Finally, we make our pipeline and analysis publicly available as a Python package called unequalpy.
| Type: | Article |
|---|---|
| Title: | The unequal-time matter power spectrum: impact on weak lensing observables |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/1475-7516/2021/08/001 |
| Publisher version: | http://dx.doi.org/10.1088/1475-7516/2021/08/001 |
| Language: | English |
| Additional information: | c 2021 The Author(s). Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | dark matter theory, galaxy clustering, weak gravitational lensing |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10136443 |
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