Abstract
NonGaussian cosmic shear statistics based on weak-lensing aperture mass (Map) maps can outperform the classical shear two-point correlation function (γ-2PCF) in terms of cosmological constraining power. However, reaching the full potential of these new estimators requires accurate modeling of the physics of baryons as the extra nonGaussian information mostly resides at small scales. We present one such modeling based on the Magneticum hydrodynamical simulation for the KiDS-450 and DES-Y1 surveys and a Euclid-like survey. We compute the bias due to baryons on the lensing PDF and the distribution of peaks and voids in Map maps and propagate it to the cosmological forecasts on the structure growth parameter S8, the matter density parameter Ωm, and the dark energy equation of state w0 using the SLICS and cosmo-SLICS sets of dark-matter-only simulations. We report a negative bias of a few percent on S8 and Ωm and also measure a positive bias of the same level on w0 when including a tomographic decomposition. These biases reach ∼5% when combining Map statistics with the γ-2PCF as these estimators show similar dependency on the AGN feedback. We verify that these biases constitute a less than 1σ shift on the probed cosmological parameters for current cosmic shear surveys. However, baryons need to be accounted for at the percentage level for future Stage IV surveys and we propose to include the uncertainty on the AGN feedback amplitude by marginalizing over this parameter using multiple simulations such as those presented in this paper. Finally, we explore the possibility of mitigating the impact of baryons by filtering the Map map but find that this process would require suppressing the small-scale information to a point where the constraints would no longer be competitive.
Highlights
Weak lensing cosmic shear is one of the most powerful cosmological probes of the late-time Universe
Baryons need to be accounted for at the percentage level for future Stage IV surveys and we propose to include the uncertainty on the active galactic nuclei (AGN) feedback amplitude by marginalizing over this parameter using multiple simulations such as those presented in this paper
Coulton et al (2020) performed this propagation and measured the impact of baryons directly on the forecasts of the matter density Ωm, the amplitude of fluctuations AS, and the sum of the neutrino masses for peaks and minima using the BAHAMAS simulations. These latter authors found larger biases for peaks than for minima in their LSST-like mock data, concluding that the latter is potentially more robust against baryons. Building on these previous analyses, and exploiting the cosmological analysis pipeline introduced in Martinet et al (2021), we measure for the first time the effect of baryons on the dark matter and dark energy cosmological parameters in a tomographic Stage-IV lensing survey setup
Summary
Weak lensing cosmic shear is one of the most powerful cosmological probes of the late-time Universe. This method accurately reproduces AGN feedback and star formation compared to hydrodynamical simulations (Aricò et al 2020) and could offer an efficient way of decreasing the computational resources needed to include baryonic effects in cosmological models This technique is not tested in the present article as it requires the particle positions, which are generally not stored for a posteriori applications. These latter authors found larger biases for peaks than for minima in their LSST-like mock data, concluding that the latter is potentially more robust against baryons Building on these previous analyses, and exploiting the cosmological analysis pipeline introduced in Martinet et al (2021), we measure for the first time the effect of baryons on the dark matter and dark energy cosmological parameters in a tomographic Stage-IV lensing survey setup. We adapt our mocks to the KiDS and DES surveys in Appendix A and measure the impact of baryons on the cosmological constraints by Martinet et al (2018); Harnois-Déraps et al (2020) in these two surveys
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