Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics [CEA]

http://arxiv.org/abs/2012.09614


Non-Gaussian cosmic shear statistics based on weak-lensing aperture mass ($M_{\rm ap}$) maps can outperform the classical shear two-point correlation function ($\gamma$-2PCF) in terms of cosmological constraining power. Reaching the full potential of these new estimators however requires an accurate modeling of the physics of baryons as the extra non-Gaussian information mostly reside at small scales. We present one such modeling based on the Magneticum hydrodynamical simulation for the KiDS-450, DES-Y1, and a Euclid-like surveys. We compute the bias due to baryons on the lensing PDF and the distribution of peaks and voids in $M_{\rm ap}$ maps and propagate it to the cosmological forecasts on the structure growth parameter $S_8$, the matter density parameter $\Omega_{\rm m}$ and the dark energy equation of state $w_0$, using the SLICS and cosmo-SLICS sets of dark matter only simulations. We report a negative bias of a few percents on $S_8$ and $\Omega_{\rm m}$ and also measure a positive bias of the same level on $w_0$ when including a tomographic decomposition. These biases are increased to the order of $\sim 5$% when combining $M_{\rm ap}$ statistics with the $\gamma$-2PCF as these estimators show similar dependency on the AGN feedback. We verify that these biases constitute less than a $1\sigma$ shift on the probed cosmological parameters for current cosmic shear surveys. Baryons, however, need to be accounted for at the percent level for future Stage IV surveys and we propose to include 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 $M_{\rm ap}$ map but find that this process would require to suppress the small-scale information to a point where the constraints would no longer be competitive.

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N. Martinet, T. Castro, J. Harnois-Déraps, et. al.
Fri, 18 Dec 20
28/78

Comments: 12 pages, 9 figures, submitted to A&A