Cassiopeia A: on the origin of the hard X-ray continuum and the implication of the observed O VIII Ly-alpha/Ly-beta distribution

Astronomy and Astrophysics – Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

5 pages, 6 figures. accepted for publication in Astronomy and Astrophysics, letters (XMM issue)

Scientific paper

10.1051/0004-6361:20000048

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.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Cassiopeia A: on the origin of the hard X-ray continuum and the implication of the observed O VIII Ly-alpha/Ly-beta distribution does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Cassiopeia A: on the origin of the hard X-ray continuum and the implication of the observed O VIII Ly-alpha/Ly-beta distribution, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cassiopeia A: on the origin of the hard X-ray continuum and the implication of the observed O VIII Ly-alpha/Ly-beta distribution will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-578881

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.