Cosmology with Sunyaev-Zeldovich observations from space

In order to assess the potential of future microwave anisotropy space experiments for detecting clusters by their Sunyaev-Zeldovich (SZ) thermal effect, we have simulated maps of the large scale distribution of their Compton parameter y and of the temperature anisotropy ∆T/T induced by their proper motion. Our model is based on a predicted distribution of clusters per unit of redshift and flux density using a Press-Schecter approach (De Luca et al. 1995). Thesemapswere used to create simulatedmicrowave sky by adding them to the microwave contributions of the emissions of our Galaxy (free-free, dust and synchrotron) and the primary Cosmic Microwave Background (CMB) anisotropies (corresponding to a COBE-normalized standard Cold Dark Model scenario). In order to simulate measurements representative of what current technology should achieve, “observations” were performed according to the instrumental characteristics (number of spectral bands, angular resolutions and detector sensitivity) of the COBRAS/SAMBA space mission. These observations were separated into physical components by an extension of the Wiener filtering theory (Bouchet et al. 1996). We then analyzed the resulting y and ∆T/T maps which now include both the primary anisotropies and those superimposed due to cluster motions. A cluster list was obtained from the recovered y maps, and their profiles compared with the input ones. Even for low y-values, the input and output profiles show good agreement, most notably in the outer parts of the profile where values as low as y ' 3. 10−7 are properly mapped. We also construct and optimize a spatial filter which is used to derive the accuracy on the measurement of the radial peculiar velocity of a detected cluster. We derive the accuracy of the mapping of the very large scale cosmic velocity field obtained from such measurements.