Orateur
Description
An accurate mass calibration of galaxy clusters is a crucial step towards precise constraints on the cosmological parameters $\sigma_8$ and $\Omega_m$ from clusters. In the millimeter, via the Sunyaev-Zel'dovich (SZ) effect, and X-rays domains, cluster masses can be estimated assuming hydrostatic equilibrium, but several physical and observational effects can alter this calculation. One of those are projection effects which are the focus of our present analysis.
As a matter of fact, any hot and ionised gas along the line of sight of clusters can contribute to the observed pressure and thus impact our analysis of the clusters' SZ or X-ray signals. Moreover, the usually assumed spherical symmetry of clusters is not always verified, so the observed properties may strongly depend on the direction of observation. Cosmological simulations permit us to study the clusters from any point of view, they are therefore well suited to study projection effects.
In this presentation, I will show the results of a case study of the simulated Virgo cluster, extracted from the CLONE constrained simulation. In this study, we analyse Virgo properties when they are projected along different directions, including along the Milky Way-Virgo axis which mimics our observation direction. By comparing the deduced hydrostatic mass and the hydrostatic mass bias from the different observation directions to the one derived from the 3D profiles, we will show and quantify the impact of projection effects on the determination of Virgo mass as a first analysis that will later be generalised to a large sample of simulated clone clusters.
