A Multi-Wavelength Study of Cluster Cosmology and Astrophysics

The background is an X-ray image from eROSITA with SZ contours (cyan) from SPT/Planck and radio contours (white) from ASKAP overlaid, with distinct radio features highlighted in white

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.