Probing the Evolution of the Gas Mass Fraction with the Sunyaev-Zeldovich Effect

Abstract

Study of the primary anisotropies of the cosmic microwave background (CMB) can be used to determine the cosmological parameters to a very high precision. The power spectrum of the secondary CMB anisotropies due to the thermal Sunyaev-Zeldovich effect (SZE) by clusters of galaxies can then be studied, to constrain more cluster-specific properties (like gas mass). We show the SZE power spectrum from clusters to be a sensitive probe of any possible evolution (or constancy) of the gas mass fraction. The position of the peak of the SZE power spectrum is a strong discriminatory signature of different gas mass fraction evolution models. For example, for a flat universe, there can be a difference in the l-values (of the peak) of as much as 2500 between a constant gas mass fraction model and an evolutionary one. Moreover, observational determination of the power spectrum, from blank-sky surveys, is devoid of any selection effects that can possibly affect targeted X-ray or radio studies of gas mass fractions in galaxy clusters.