TELESCOPE SEARCH FOR A 3-EV TO 8-EV AXION

Axions of mass 3-8 eV should have a cosmological abundance of about 50 cm-3 and reside in rich clusters of galaxies. Their decays to two photons will produce a line at a wavelength lambda-alpha approximately 3100-8300 angstrom (width DELTA-lambda/lambda approximately 10(-2)). We have searched unsuccessfully for such a feature in the intergalactic light of three rich clusters, closing this "window," and leaving open only the window from 10(-6) to 10(-3) eV. This implies that if the axion exists, it likely comprises the dark matter. Our flux limits are of relevance to other relics whose decays produce monoenergetic photons.