Document Type


Publication Date

Fall 10-1-1995

Publication Title

Astronomy & Astrophysics


EDP Sciences


We present all OSSE observation to date the Cas A supernova remnant. The objective are to detect the 44Ti lines, one of which has been reportedly detected by COMPTEL, and the hard X-ray continum above 40 keV, as indicated by HEAO-A2 measurements. Our best fit flux in each of three 44Ti lines is (+1.76±1.51/1.48) x 10^-5 gamma cm^-2 s^-1 with X2v = 1.01, d.o.f. = 1780. The implied 44Ti mass ~10^-4 M⊙ is compatible with explosive nucleosynthesis calculations. OSSE detected also a continuum below 200 keV at better than 4σ confidence level with a flux of ~9 x 10^-4 gamma cm^-2 s^-1 MeV^-1 at 100 keV. This continuum can be fitted equally well with a power law, an exponential, or a thermal bremsstrahlung model. The impled temperature of kT=35 keV can be interpreted as the emission from the shcoked circumstellar matter (CSM) by the primary blastwave of the supernova. Alternatively, the continuum can also be interpreted as bremsstrahlung from accelerated electron that are also producing the observed radio emission.