Last Modified 23 August 1999Webpage Administrator.
The initial cluster simulations were made (by Vince Eke) by taking N-body/hydro simulations of rich clusters and projecting the gas pressure onto three perpendicular planes to make a set of template SZ images. Clusters were then laid down in a cone corresponding to a fixed field of view with a mass function in each redshift bin given by the Press-Schechter formula appropriate for each cosmology. Tempertures were scaled with the mass in order to agree with the observed temperature-X-ray luminosity relation.
These simulated skies were then `observed' by taking a random patch of the simulation and multiplying by a field-of-view appropriate to an AMI survey. This image was then fourier transformed and sampled at points determined by a model of the tracking geometry of the AMI arrays, to form model interferometer visibilities. Noise was added to each model visibility appropriate to a total observing time of 360 h, and then standard techniques were used to make dirty maps and beams, and to deconvolve the resulting images.
The Ryle Telescope image is a real observation, from K Grainge PhD Thesis (University of Cambridge 1996). The AMI image was made by taking the ROSAT PSPC X-ray image raised to the power 1/3, since in the standard King model with beta=2/3, the X-ray surface brightness goes as r^(-3/2) while the SZ surface brightness goes as r^(-1/2). This image was then scaled to give a consistent SZ flux to the RT observation, and a model AMI observation made as above.
The simulated image of the Kaiser-Stebbins effect is from Bouchet, Bennet & Stebbins (1988), with AMI observations made again as above. In practice this smooth sky with sharp k-s features from post-recombination strings is not expected, as gaussian contributions from the last scattering surface will have similar amplitude. However, the recovery of non-gaussian signals from gaussian contamination is possible using, for example, wavelet transform techniques, with gassian:non-gaussian amplitude ratios as high as 5:1 (Hobson 1999).
Last Modified 23 August 1999
Webpage Administrator.