Showing papers by "Nabila Aghanim published in 1997"

Cosmology with Sunyaev-Zeldovich observations from space.

Abstract: 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 param- eter y and of the temperature anisotropy T=T induced by their proper motion. Our model is based on a predicted distri- bution of clusters per unit of redshift and flux density using a Press-Schecter approach (De Luca et al. 1995). Thesemapswereusedtocreatesimulatedmicrowaveskyby 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 (corre- sponding 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 (num- ber of spectral bands, angular resolutions and detector sensitiv- ity) of the COBRAS/SAMBA space mission. These observa- tions were separated into physical components by an extension of the Wiener ltering 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 proles compared with the input ones. Even forlowy-values,theinputandoutputprolesshowgoodagree- ment, most notably in the outer parts of the prole where values as low as y ' 3:10 7 are properly mapped. We also construct and optimize a spatial lter 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 eld obtained from such measurements.

Cosmology with Sunyaev-Zeldovich observations from space

Abstract: 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 $\Delta T/T$ induced by their proper motion. Our model is based on a predicted distribution of clusters per unit redshift and flux density using a Press-Schecter approach. These maps were used to create simulated microwave sky by adding them to the microwave contributions of the emissions of our Galaxy and the primary Cosmic Microwave Background (CMB) anisotropies. In order to simulate measurements representative of what current technology should achieve, ``observations'' were performed according to the instrumental characteristics of the COBRAS/SAMBA space mission. We then analyzed the resulting $y$ and $\Delta T/T$ maps which now include both the primary anisotropies and those superimposed due to cluster motions.