  We present the first results on the hard X-ray continuum image (up to 15 keV)
of the supernova remnant Cas A measured with the EPIC cameras onboard
XMM-Newton. The data indicate that the hard X-ray tail, observed previously,
that extends to energies above 100 keV does not originate in localised regions,
like the bright X-ray knots and filaments or the primary blast wave, but is
spread over the whole remnant with a rather flat hardness ratio of the 8-10 and
10-15 keV energy bands. This result does not support an interpretation of the
hard X-radiation as synchrotron emission produced in the primary shock, in
which case a limb brightened shell of hard X-ray emission close to the primary
shock front is expected. In fact a weak rim of emission near the primary shock
front is discernable in the hardest X-ray image but it contains only a few
percent of the hard X-ray emissivity. The equivalent width of the Fe-K line
blend varies by more than an order of magnitude over the remnant, it is hard to
explain this as Fe-emission from the reverse shock heated ejecta given the
ejecta temperature and the age of the remnant. The uniquely high
wavelength-dispersive RGS-spectrometer has allowed, for the first time, to
extract monochromatic images in several highly ionised element species with
high spectral resolution. We present here a preliminary result on the
measurement of the O VIII Ly-alpha and Ly-beta brightness distribution and
brightness ratios. The large observed decrease of the Ly-alpha/Ly-beta ratio
going from the N to the SE can be explained by small-scale (10 arcsec)
variations in the N_H column over the remnant and the potential presence of
resonance scattering of the O VIII Ly-alpha photons in the limb brightened
shell.
