Gamma Rays from SN 1987A due to Pseudoscalar Conversion.

Abstract

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 $\ensuremath{\gamma}$ rays by the galactic magnetic field. Measurements on the SN 1987A $\ensuremath{\gamma}$-ray flux by the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite already imply a bound on the coupling $gl3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}{\mathrm{GeV}}^{\ensuremath{-}1}$. The improved generation of satellite-borne detectors, like EGRET or the project GLAST, could be able to detect a pseudoscalar-to-photon signal from a nearby supernova, for allowed values of $g$.