X-ray and gamma-ray fluxes from SN 1987A

In an attempt to fit the gamma-ray line fluxes and the Ginga (16-28 keV) X-ray fluxes from SN 1987A, we have performed Monte Carlo simulations of gamma-ray transport in published models of the SN 1987A debris. In addition, we have investigated individually the effects in these models of changing the mass density, the velocity profile, and the ⁵⁶Ni distributions. We have calculated the Ginga and gamma-line light curves, the X-ray (Comptonization) spectra, the zone-by-zone contributions to the gamma-line, X-ray, and ultraviolet, optical, infrared (bolometric) fluxes, and the relative contribution to debris heating of Compton scattering, photoelectric absorption, and positron scattering. Both the ⁵⁶Ni and the ⁵⁷Ni decay chains are included as sources. We also calculate the observability and emergence times of X-rays from a buried neutron star. The characteristics of the debris that best fit the observed X-ray and gamma-ray photon fluxes are discussed. We find that the Ginga data beyond day 600 cannot be fitted by any reasonable radioactive model and, therefore, that either background source confusion (or perhaps an additional in situ source) is indicated. We show, in support of the work of Woosley, Pinto, and Ensman, that barring any nonradioactive source in SN 1987A, the observation at late times (>800 days) of the hard X-ray flux below the ⁵⁷Co lines at 122 and 136 keV will allow us to determine the important ⁵⁷Co abundance directly. We find that the X-ray continuum between the ⁵⁷Co lines and 511 keV is now almost exclusively from the Comptonization of photons from the annihilation of the ⁵⁶Co positron.