Large scale pressure fluctuations and the Sunyaev-Zel’dovich effect

Abstract

The Sunyaev-Zel'dovich (SZ) effect associated with pressure fluctuations of the large scale structure gas distribution will be probed with current and upcoming wide-field small angular scale cosmic microwave background experiments. We study the generation of pressure fluctuations by baryons which are present in virialized dark matter halos, with overdensities > ∼ 200 and by baryons present in overdensities < ∼ 10. For collapsed halos, assuming the gas distribution is in hydrostatic equilibrium with matter density distribution, we predict the pressure power spectrum and bispectrum associated with the large scale structure gas distribution by extending the dark matter halo approach which describes the density field in terms of correlations between and within halos. The projected pressure power spectrum allows a determination of the resulting SZ power spectrum due to virialized structures. The unshocked photoionized baryons present in smaller overdensities trace the Jeans-scale smoothed dark matter distribution. They provide a lower limit to the SZ effect due to large scale structure in the absence of massive collapsed halos. We extend our calculations to discuss higher order statistics, such as bispectrum and skewness in SZ data. The SZ-weak lensing cross-correlation is suggested as a probe of correlations between dark matter and baryon density fields, while the probability distribution functions of peak statistics of SZ halos in wide field CMB data can be used as a probe of cosmology and non-Gaussian evolution of large scale pressure fluctuations.

Small-scale cosmic microwave background polarization from reionization

“…[15], although differs in that we present a simplified derivation of the results based on a flat-sky approximation and use a haloclustering approach [16] to describe fluctuations in the electron density, in analogy to similar recent calculations of small-scale temperature fluctuations from unresolved clusters [8,17,18]. We also include for the first time the frequency dependence in the small-scale polarization using results for the polarization from individual clusters [19,20].…”

“…We thus decompose the power spectrum into two parts, one that describes contributions from single halos (1-halo term) and a part that accounts for correlations between halos (2-halo term) [8,17,18,23]:…”

Numerical and analytical predictions for the large-scale Sunyaev-Zel’dovich effect

“…In this paper, we combine the approaches of Refregier et al [19] and of Cooray [21] to carefully compare predictions from numerical simulations to that from the extended halo model. We use a recently developed Adaptative Mesh Refinement (AMR) hydrodynamical code, called RAMSES (see Teyssier [23] for a complete presentation), to compute the power spectrum of the gas pressure and of the Dark Matter (DM) density in a ΛCDM universe.…”

“…Aghanim et al [8], Atrio-Barandela & Mücket [11] and Komatsu & Kitayama [12] used the Press & Schechter formalism [35] to predict the SZ power spectrum in various CDM models. In the same spirit, Cooray [21] recently used a self-consistent extended halo model [30,29] to make analytical predictions for the large-scale SZ effect. In a different approach, Zhang & Pen [22] recently presented analytical predictions based on hierarchical clustering and non-linear perturbation theory.…”

Surveys of Galaxy Clusters with the Sunyaev‐Zel’dovich Effect

“…We use T Ã $ 1 throughout, 3 which gives good agreement for the redshift evolution of the mean mass-weighted temperature and the angular power spectrum of y when compared with the results of hydrodynamic simulations . In particular, this method provides a better fit to the shape of the simulation based angular power spectrum, especially over the peak, than semianalytic methods (Komatsu & Kitayama 1999;Cooray 2000;Molnar & Birkinshaw 2000;Holder & Carlstrom 2001;Komatsu & Seljak 2002). As our approach has isothermal clusters, with a deterministic temperature derived solely from the mass, this somewhat limits the possible sources of discrepancy between the semianalytic and hydrodynamic calculations.…”