Principal Investigator
Carlos J. A. P. Martins

Abstract
One of the most precise cosmological measurements is the intensity spectrum of the Cosmic Microwave Back-ground. If the expansion of the Universe is adiabatic and the CMB spectrum was originally a black-body, its shape will be subsequently preserved with its temperature decreasing according to the law T=T_0(1+z). This temperature-redshift relation is one of the strongest predictions of the standard model of cosmology, but it will be violated in many non-standard models, e.g. those with extra dimensions (like string theory) and those where couplings like the fine-structure constant vary with redshift. To distinguish between models one must measure this relation at high redshifts, trough observations of the Sunyaev-Zel'dovich (SZ) effect, the inverse Compton scattering of the CMB radiation by hot plasma trapped inside galaxy clusters. With a new generation of ground experiments entering in operation and an all-sky survey of SZ clusters to be carried out by the ESA Planck Surveyor satellite, the potential of this method will come to fruition, allowing for the first detailed tests of cosmology and fundamental physics scenarios. The goal of the project is to carry out a pioneering evaluation of the potential of galaxy clusters as probes of the CMB temperature-redshift relation (and hence of cosmology and fundamental physics), bearing in mind the forthcoming SZ surveys. We'll gain a phenomenological understanding of the expectations for deviations to the standard law, and of the cosmological and particle physics scenarios that may lead to them. We will estimate the degree of accuracy with which upcoming cluster surveys will constrain the CMB temperature redshift relation, using simulated cluster catalogues processed according to survey specifications. Finally, we will build upon previous work on the use os SZ observations as a probe of cosmological parameters, in particular by including the possibility of a varying fine-structure constant in the analysis.

Portuguese Node: CAUP
Co-PI: Carlos Martins

Spanish Node: Universidad de Salamanca
Co-PI:Fernando Atrio-Barandela

Start
1 January 2011
End
30 June 2012

Funding Institution
Fundação para a Ciência e a Tecnologia