GAMMA-RAYS FROM SN 1987A DUE TO PSEUDOSCALAR CONVERSION

A light pseudoscalar coupled to two photons would be copiously emitted by the core of a supernova. Part of this flux would be converted to g amma rays by the galactic magnetic field. Measurements on the SN 1987A gamma-ray flux by the Gamma-Ray Spectrometer on the Solar Maximum Mis sion satellite already imply a bound on the coupling g < 3 X 10(-12) G eV-1. The improved generation of satellite-borne detectors, like EGRET or the project GLAST, could be able to detect a pseudoscalar-to-photo n signal from a nearby supernova, for allowed values of g.