10:00–11:00 am ERC 501
Zhuowen (Ben) Zhang "Forward modeling of cluster systematics for cluster cosmology"
Galaxy clusters are powerful probes for cosmology. In the optical regime, measurements of the cluster abundance inferred from their weak lensing masses can be used to constrain Omega_m, the matter density of the universe, and sigma_8, the matter density fluctuation. However, cluster observables suffer a range of systematics that hamper their ability to achieve state-of-the-art constraints. My thesis work quantitatively resolves several of these systematics. First, I quantify the impact of triaxiality, or the impact on cluster observables due to the ellipsoidal shape of clusters, as well as explore the relation between triaxiality and other major systematics as miscentering and projection effects. I then explore a hitherto unexplored systematic of the covariance between cluster observables. I first quantify the intrinsic covariance of cluster signals due to the underlying formation physics. I then apply a realistic cluster finder to quantify the impact that extrinsic terms due to observational effects have on the covariance. These results have been included in current optical surveys as DES and HSC and will be useful for stage IV cluster surveys as LSST and DESI.
