Pseudoscalar Conversion and Gamma-Rays from Supernovae

A light pseudoscalar coupled to two photons would be copiously emitted by the core of a supernova and part of this flux would be converted to gamma-rays by the galactic magnetic field. Measurements on the SN1987A gamma-ray flux by the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite imply stringents bounds on such process. The improved generation of satellite-borne detectors, like EGRET or the projegeneration of satellite-borne detectors, like EGRET or the project GLAST, could be able to detect a pseudoscalar-to-photon signal from a nearby supernova.