1 DSM/DAPNIA/SAp, CEA-Saclay, 91191 Gif sur Yvette Cedex FRANCE
Until recently, detailed cluster studies were restricted to nearby clusters (z < 0.1). Nowadays, new imaging as well as spectroscopic capabilities (visible, X-ray, IR, radio) have considerably improved our view of the distant universe. In this context, we have selected a sample of 7 bright clusters from the ROSAT All Sky Survey in the z = 0.1 - 0.3 range in order to investigate issues ranging from cluster formation and evolution down to a local phenomena such as the enrichment of the ICM. We have undertaken a detailed high-resolution multi-wavelength follow-up including ROSAT HRI and PSPC, ASCA pointings, Radio images at 3,6,13,20 and 36 cm and extensive photometry and spectroscopy in the optical. The clusters have been observed by ISO in the Central Programme (DEEPXSRC, 30 hours), at 6.75 and 15 microns with ISOCAM and at 90 microns with ISOPHOT. We present a comprehensive study of the ISO cluster galaxies in connection with the other wavelengths and with a comparison sample of field galaxies.
Surprisingly, we have discovered that most emission line galaxies are not detected with ISOCAM, which suggests non-trivial connections between star formation rate, optical and mid-IR properties. Each cluster type (relaxed, dynamically perturbated, merger, lens-cluster, AGN dominated, ...) shows different IR signatures, for example we observe a correlation between the 100 microns emission and the presence of a radio halo in A1300. We shall also discuss the mid-IR activity in our clusters as a function of the ICM density and gravitational potentiel strength.