1. Joint constraints on cosmology and the impact of baryon feedback: combining KiDS-1000 lensing with the thermal Sunyaev-Zeldovich effect from Planck and ACT
- Author
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Tilman Tröster, Alexander J. Mead, Catherine Heymans, Ziang Yan, David Alonso, Marika Asgari, Maciej Bilicki, Andrej Dvornik, Hendrik Hildebrandt, Benjamin Joachimi, Arun Kannawadi, Konrad Kuijken, Peter Schneider, Huan Yuan Shan, Ludovic van Waerbeke, and Angus H. Wright
- Subjects
Cosmology - observations ,Gravitational lensing - weak ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Large-scale structure of Universe ,Space and Planetary Science ,Cosmological parameters ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We conduct a pseudo-$C_\ell$ analysis of the tomographic cross-correlation between 1000 deg$^2$ of weak lensing data from the Kilo-Degree Survey (KiDS-1000) and the thermal Sunyaev-Zeldovich (tSZ) effect measured by Planck and the Atacama Cosmology Telescope (ACT). Using HMx, a halo-model-based approach that consistently models the gas, star, and dark matter components, we are able to derive constraints on both cosmology and baryon feedback for the first time from these data, marginalising over redshift uncertainties, intrinsic alignment of galaxies, and contamination by the cosmic infrared background (CIB). We find our results to be insensitive to the CIB, while intrinsic alignment provides a small but significant contribution to the lensing--tSZ cross-correlation. The cosmological constraints are consistent with those of other low-redshift probes and prefer strong baryon feedback. The inferred amplitude of the lensing--tSZ cross-correlation signal, which scales as $\sigma_8(\Omega_\mathrm{m}/0.3)^{0.2}$, is low by $\sim 2\,\sigma$ compared to the primary cosmic microwave background constraints by Planck. The lensing--tSZ measurements are then combined with pseudo-$C_\ell$ measurements of KiDS-1000 cosmic shear into a novel joint analysis, accounting for the full cross-covariance between the probes, providing tight cosmological constraints by breaking parameter degeneracies inherent to both probes. The joint analysis gives an improvement of 40% on the constraint of $S_8=\sigma_8\sqrt{\Omega_\mathrm{m}/0.3}$ over cosmic shear alone, while providing constraints on baryon feedback consistent with hydrodynamical simulations, demonstrating the potential of such joint analyses with baryonic tracers such as the tSZ effect. We discuss remaining modelling challenges that need to be addressed if these baryonic probes are to be included in future precision-cosmology analyses., Comment: 21 pages, 16 figures. Accepted in A&A. Comments welcome. Code, data vectors, and covariances are available at https://github.com/tilmantroester/KiDS-1000xtSZ
- Published
- 2021
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