ON THE CLUSTER PHYSICS OF SUNYAEV-ZEL'DOVICH AND X-RAY SURVEYS. II. DECONSTRUCTING THE THERMAL SZ POWER SPECTRUM

Abstract

Secondary anisotropies in the cosmic microwave background are a\ntreasure-trove of cosmological information. Interpreting current experiments\nprobing them are limited by theoretical uncertainties rather than by\nmeasurement errors. Here we focus on the secondary anisotropies resulting from\nthe thermal Sunyaev-Zel'dovich (tSZ) effect; the amplitude of which depends\ncritically on the average thermal pressure profile of galaxy groups and\nclusters. To this end, we use a suite of SPH simulations that include radiative\ncooling, star formation, supernova feedback, and energetic feedback from active\ngalactic nuclei (AGN). We examine in detail how the pressure profile depends on\ncluster radius, mass, and redshift and provide an empirical fitting function.\nWe employ three different approaches for calculating the tSZ power spectrum: an\nanalytical approach that uses our pressure profile fit, a semi-analytical\nmethod of pasting our pressure fit onto simulated clusters, and a direct\nnumerical integration of our simulated volumes. We demonstrate that the\ndetailed structure of the intracluster medium and cosmic web affect the tSZ\npower spectrum. In particular, the substructure and asphericity of clusters\nincrease the tSZ power spectrum by 10-20% at ell ~2000-8000, with most of the\nadditional power being contributed by substructures. The contributions to the\npower spectrum from radii larger than R_500 is ~ 20% at ell = 3000, thus\nclusters interiors (r < R_500) dominate the power spectrum amplitude at these\nangular scales.\n

Keywords

Affiliated Institutions

• Carnegie Mellon University US
• University of Toronto CA
• Canadian Institute for Theoretical Astrophysics CA
• Heidelberg Institute for Theoretical Studies DE
• Princeton University US

Related Publications