ROSAT and BeppoSAX evidence of soft X-ray excess emission in the Shapley supercluster:: A3571, A3558, A3560, and A3562

Excess soft X-ray emission in clusters of galaxies has so far been detected for sources that lie along lines of sight to very low Galactic H I column density [such as Coma, A1795, A2199, and Virgo; N(H)similar to (0.9-2.0) x 10(20) cm(-2)]. We show that the cluster soft excess emission can be investigated even at higher N-H, which provides an opportunity for investigating soft X-ray emission characteristics among a large number of clusters. The ROSAT Position Sensitive Proportional Counter analysis of some members of the Shapley concentration [A3571, A3558, A3560, and A3562 at N(H)similar to (4-4.5) x 10(20) cm(-2)] bears evidence for excess emission in the 1/4 keV band. We were able to confirm the finding for the case of A3571 by a pointed BeppoSAX observation. Within the current sample, the soft X-ray flux is again found to be consistently above the level expected from a hot virialized plasma. The data quality is, however insufficient to enable a discrimination between alternative models of the excess low-energy flux.