Broad band properties of medium and low Lx/Lb early type galaxies

We have measured the spectral properties of five galaxies of low to intermediate Lx/Lb ratios with BeppoSAX and ASCA. A hard component (kT ∼ 4 − 10 keV) is observed in all galaxies. In NGC 1553 the BeppoSAX data show that this component is extended, and suggest an origin for the emission in the evolved stellar population. In NGC 3115, a point-like source appears embedded in an extended component morphologically similar to the stellar body, suggesting an almost equal contribution from the nuclear region and the binary population. A large central mass concentration and low level optical activity in NGC 3379 argue for a contribution from the nucleus also in this object. However, for both NGC 3115 and NGC 3379, the nuclear emission is at a level well below that observed in other galaxies who host similar nuclear black holes. A second soft (kT ∼0.30.7 keV) spectral component is needed to fit the data of NGC 1407, NGC 1553 and NGC 4125 over the entire energy range probed (∼0.2-10 keV), best represented by a thermal component with line emission. We discuss possible interpretations of the origin of this component, which however will be better defined only with higher quality data.