EXOSAT observations of two gamma-ray burst sources
Hurley, K.; Motch, C.; Boer, M.; Niel, M.; Branduardi-Raymont, G.; Ilovaisky, S.; Laros, J. G.; Klebesadel, R. W.; Martin, C.; Taylor, B. G.; Fenimore, E. E.; Mason, K.; Pizzichini, G.; Sims, M. R.; Middleditch, J.; Barat, C.; Chevalier, C.; Cordova, F.; Evans, W. D.; Attéia, J. -L.; Bonnazola, S.
France
Abstract
EXOSAT observations of the 19 Nov 1978 and 25 Mar 1979b gamma bursters are presented, for the 0.02-2.5 keV energy range. No source was detected in either case, leading to temperature upper limits for the neutron stars assumed to be present of 105-106 °K. Polar cap accretion rates are constrained to values of 10-12-10-18 Msolar/y km2. The EXOSAT non-detection of the source discovered by the Einstein satellite in the 19 Nov 1978 error box may be explained if the burster is more distant than about 1.5 kpc.