REEXAMINING THE LYMAN CONTINUUM IN STARBURST GALAXIES OBSERVED WITH THE HOPKINS ULTRAVIOLET TELESCOPE

We have reevaluated the constraints on the Lyman continuum emission fr om four starburst galaxies observed with the Hopkins Ultraviolet Teles cope (HUT) during the Astro-2 mission. Applying a detailed model of th e absorption by interstellar gases in our Galaxy, and using the latest HUT data products, we find upper limits to the redshifted Lyman conti nuum that are less restrictive than those reported previously. Well-de termined astrophysical and instrumental effects permit 2 sigma upper l imits no tighter than 5.2%, 11%, 57%, and 3.2% to be set on the escape fraction of Lyman continuum photons from IRAS 08339 + 6517, Mrk 1267, Mrk 66, and Mrk 496, respectively. Absorption from undetected interst ellar components (including H-2) Or modulation of the emergent spectru m by gas or dust in the parent galaxy could allow the true escape frac tions to exceed these revised upper limits.