Discovery of the central excess brightness in hard X-rays in the cluster of galaxies Abell 1795

Using the X-ray data from ASCA, spectral and spatial properties of the intracluster medium (ICM) of the cD cluster Abell 1795 are studied up to a radial distance of similar to 12' (similar to 1.3 h(50)(-1) kpc). The ICM temperature and abundance are spatially rather constant, although the cool emission component is reconfirmed in the central region. The azimuthally averaged radial X-ray surface brightness profiles are very similar between soft (0.7-3 keV) and hard (3-10 keV) energy bands, and neither can be fitted with a single-beta model due to a strong data excess within similar to 5' of the cluster center. In contrast, double-beta models can successfully reproduce the overall brightness profiles both in the soft and hard energy bands, as well as that derived with the ROSAT PSPC. Properties of the central excess brightness are very similar over the 0.2-10 keV energy range spanned by ROSAT and ASCA. Thus, the excess X-ray emission from the core region of this cluster is confirmed for the first time in hard X-rays above 3 keV. This indicates that the shape of the gravitational potential becomes deeper than the King-type one toward the cluster center. Radial profiles of the total gravitating matter, calculated using the double-beta model, reveal an excess mass of similar to 3 x 10(13) Mg within similar to 150 h(50)(-1) kpc of the cluster center. This suggests a hierarchy in the gravitational potential corresponding to the cD galaxy and the entire cluster.