A Multi-Wavelength Study of Cluster Cosmology and Astrophysics

Abstract:

Galaxy clusters are powerful probes of both cosmology and astrophysics, tracing the growth of large-scale structure while providing a laboratory for studying the physics of the intracluster medium (ICM) and Active Galactic Nuclei (AGN). In this talk, I will present my thesis work which uses multi-wavelength observations and simulations to characterize key astrophysics that affect cluster-based cosmological measurements. I will discuss how millimeter emission from cluster-member AGNs contaminates Sunyaev-Zel’dovich (SZ) cluster surveys, including our recovery of two clusters in ACT maps using CARMA data. Building on this work, I will present our plans for ongoing ATCA observations of millimeter-bright AGNs in the SPT-Deep field, which will provide the first constraints on AGN-induced biases in a complete SZ-selected cluster sample. I will also discuss our previous work to quantify the impact of another astrophysical systematic, cluster triaxiality, on SZ selection, which further leads to biases in weak-lensing mass estimates. To quantify the effect of this triaxiality, our collaboration is developing a multi-probe framework that combines X-ray, SZ, and weak-lensing observations of clusters to constrain cluster geometry, improve mass measurements, and probe dark matter physics and mass accretion histories. In addition, I will discuss ongoing work on cluster scaling relations using both observations and simulations, with the goals of identifying low-scatter mass proxies and quantifying correlations between cluster observables. Finally, I will present our work characterizing non-thermal pressure support in the ICM of clusters through combined SZ and X-ray fluctuation measurements, representing the first such analysis using eROSITA and SZ data.

Location

Organiser