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 γ−rays by the galactic magnetic field. Measurements on the SN1987A γ−ray flux by the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite already imply a bound on the coupling g < 3×10 GeV. The improved generation of satellite-borne detectors, like EGRET or the project GLAST, could be able to detect a pseudoscalar-tophoton signal from a nearby supernova, for allowed values of g. Submitted for publication