Hard X Rays from Supernova 1993J
NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
Pagination or Media Count:
The Oriented Scintillation Spectrometer Experiment OSSE on the Compton Observatory observed SN 1993J during three intervals centered approximately 12, 30, and 108 days after its outburst. Hard X-ray emission was detected in the first two of these intervals. No emission was seen in the third observation or in two earlier observations in 1991 and 1992. The coincidence of the observed excess with the outburst of SN 1993J and the consistency of the spectra and time evolution with those seen at lower energies by ROSAT and ASCA argue that the observed emission is indeed from SN 1993J. It is probably due the interaction of the fast supernova ejecta with circumstellar material. The luminosity, 5x10exp 40 erg sexp -1 50-150 keV in the first interval, is significantly larger than predicted. Extrapolating the spectrum to a few keV accounts for most or all of the observed emission at low energy. The observed high temperature, 10exp 9 K, is easily obtained in the shocked circumstellar matter, but a surprisingly high density is required there to give the observed luminosity and little or no additional X-ray emission from denser shocked supernova ejecta is allowed. The hard emission might also be explained in terms of the shocked supernova ejecta itself with unexpectedly high temperature.
- Nuclear Physics and Elementary Particle Physics