Cosmology from the Thermal Sunyaev-Zel'dovich Power Spectrum: Primordial non-Gaussianity and Massive Neutrinos

TL;DR

This paper evaluates how upcoming CMB observations can constrain cosmological parameters like primordial non-Gaussianity and neutrino masses through the thermal Sunyaev-Zel'dovich power spectrum, highlighting the potential and limitations of current and future experiments.

Contribution

It provides detailed forecasts for constraints on primordial non-Gaussianity and neutrino masses from the tSZ power spectrum using various CMB experiments, including Planck and future CV-limited setups.

Findings

Planck can detect the tSZ power spectrum with >30-sigma significance.

Current experiments have limited ability to constrain fNL due to cosmic variance.

Future CV-limited experiments could detect fNL~37 at 3-sigma significance.

Abstract

We carry out a comprehensive analysis of the possible constraints on cosmological and astrophysical parameters achievable with measurements of the thermal Sunyaev-Zel'dovich (tSZ) power spectrum from upcoming full-sky CMB observations, with a particular focus on one-parameter extensions to the LCDM standard model involving local primordial non-Gaussianity (described by fNL) and massive neutrinos (described by Mnu). We include all of the relevant physical effects due to these additional parameters, including the change to the halo mass function and the scale-dependent halo bias induced by local primordial non-Gaussianity. [...] We compute forecasts for Planck, PIXIE, and a cosmic variance (CV)-limited experiment, using multifrequency subtraction to remove foregrounds and implementing two masking criteria based on the ROSAT and eROSITA cluster catalogs to reduce the significant CV errors at low multipoles. We find that Planck can detect the tSZ power spectrum with >30-sigma significance, regardless of the masking scenario. However, neither Planck or PIXIE is likely to provide competitive constraints on fNL from the tSZ power spectrum due to CV noise at low-ell overwhelming the unique signature of the scale-dependent bias. A future CV-limited experiment could provide a 3-sigma detection of fNL~37, which is the WMAP9 maximum-likelihood result. The outlook for neutrino masses is more optimistic: Planck can reach levels comparable to the current upper bounds ~<0.3 eV with conservative assumptions about the intracluster medium (ICM); stronger ICM priors could allow Planck to provide 1-2-sigma evidence for massive neutrinos from the tSZ power spectrum, depending on the true value of the sum of the neutrino masses. We also forecast a ~<10% constraint on the outer slope of the ICM pressure profile using the unmasked Planck tSZ power spectrum.