A 1-per cent-accurate method to include baryonic effects in galaxy–galaxy lensing models

Monthly Notices of the Royal Astronomical Society, vol. 544, pp. 3512–3532

Abstract

ABSTRACT The clustering of galaxies and galaxy–galaxy lensing are two of the main observational probes in Stage-IV large-scale structure surveys, such as Euclid and LSST. Unfortunately, the complicated relationship between galaxies and matter greatly limits the exploitation of this data. Sophisticated theoretical galaxy bias models–such as the hybrid Lagrangian bias expansion – allow describing galaxy clustering down to scales as small as $k = 0.7 ~ h ~ \mathrm{Mpc}^{-1}$. However, the galaxy–matter cross-power spectra are already affected by baryons on these scales, directly impacting the modelling of galaxy–galaxy lensing. In this work, we propose a way to extend state-of-the-art models of the galaxy–matter cross-power spectrum $P_{\rm gm}(k)$ (currently only accounting for dark matter) by including a baryonic correction term inferred from the matter component [the suppression $S_{\rm mm}(k) = P_{\rm mm, full \, physics} / P_{\rm mm, gravity \, only}$], so that $P_{\rm gm, full \, physics} (k) = \sqrt{S_{\rm mm}} P_{\rm gm, gravity \, only}$. We use the FLAMINGO hydrodynamical simulations to measure the effect of baryons on the galaxy–matter cross-power spectrum and to assess the performance of our model. Specifically, we perform a Bayesian analysis of synthetic data, implementing a model based on BACCO’s hybrid Lagrangian bias expansion (for the non-linear galaxy bias) and Baryon Correction Model (for the baryon suppression of the matter power spectrum). Ignoring the effect of baryons on the galaxy–matter cross-power spectrum leads to a biased inference of the galaxy bias parameters, while ignoring baryons in both the galaxy–matter and matter–matter power spectra leads to a biased inference of both the galaxy bias and cosmological parameters. In contrast, our method is 1 per cent accurate compared to all physics variations in FLAMINGO and on all scales described by hybrid perturbative models ($k < 0.7 ~ h ~ \mathrm{Mpc}^{-1}$). Moreover, our model leads to inferred bias and cosmological parameters compatible within 1$\sigma$ with their reference values. We anticipate that our method will be a promising candidate for analysing forthcoming Stage-IV survey data.

Authors 8

1. Matteo Zennaro corresponding

   University of Oxford

   Affiliation as printed

   University of Oxford Department of Physics (Astrophysics), , Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH ,

   Department of Physics (Astrophysics), University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK

2. Giovanni Aricò

   University of Zurich

   Affiliation as printed

   Institut für Astrophysik (DAP), Universität Zürich , Winterthurerstrasse 190, CH-8057 Zürich ,

   Institut für Astrophysik (DAP), Universität Zürich , Winterthurerstrasse 190, 8057 Zürich ,

3. Raúl E. Angulo

   Ikerbasque · Donostia International Physics Center

   Affiliation as printed

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea , 4, E-20018 Donostia , Gipuzkoa,

   IKERBASQUE, Basque Foundation for Science , E-48013 Bilbao ,

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea, 4, 20018 Donostia, Gipuzkoa, Spain

   IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain

4. Lurdes Ondaro-Mallea

   University of the Basque Country · Donostia International Physics Center

   Affiliation as printed

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea , 4, E-20018 Donostia , Gipuzkoa,

   University of the Basque Country UPV/EHU Department of Theoretical Physics, , E-48080 Bilbao ,

   Department of Theoretical Physics, University of the Basque Country UPV/EHU, Bilbao, E-48080, Spain

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea, 4, 20018 Donostia, Gipuzkoa, Spain

5. Sergio Contreras

   Donostia International Physics Center

   Affiliation as printed

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea , 4, E-20018 Donostia , Gipuzkoa,

   Donostia International Physics Center, Manuel Lardizabal Ibilbidea, 4, 20018 Donostia, Gipuzkoa, Spain

6. Andrina Nicola

   University of Manchester

   Affiliation as printed

   Department of Physics and Astronomy, The University of Manchester Jodrell Bank Centre for Astrophysics, , Manchester M13 9PL ,

   Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK

7. Matthieu Schaller Aachen Leiden Observatory Lorentz Institute for Theoretical Physics

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden ,

   Lorentz Institute for Theoretical Physics, Leiden University , PO Box 9506, NL-2300 RA Leiden ,

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands

8. Joop Schaye Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden ,

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands