Gamma-ray continuum and line observations of SN 1987A

Abstract

The Caltech y-ray imaging telescope observed the hard X-ray and γ-ray emission from SN 1987A as it evolved between 1987 May and 1989 April, in a series of four balloon flights from Alice Springs, NT, Australia. Observations of the Crab Nebula and Pulsar provided in-flight data on pointing accuracy and instrument function for each flight. Results presented here include our measurements on 1987 November 18, (D268) and 1988 April 12, (D414) of both line emission at 847 and 1238 keV from the decay of ^(56)Co, and Compton-scattered continuum above 50 keV. Upper limits for both line and continuum emission were obtained on 1987 May 20, (D86) and 1989 April 4, (D771). For the D268 and D414 continuum measurements, our results are best-fit by a differential power law of the form dN/dE = κE^(-γ) (cm^(-2) s^(-1) keV) for the energy range 50-800 keV. Our corresponding line measurements were fit with Gaussian profiles, containing additional terms for the underlying continuum. We compare our flux measurements and upper limits to those from other experiments and to predictions of theoretical models.