Previous abstract Next abstract

Session 69 - Starburst Galaxies.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[69.03] Observing Near the Galactic Lyman Limit: Revisions to the Ionizing Flux from Starburst Galaxies Observed with HUT

M. Hurwitz, P. Jelinsky, W. V. D. Dixon (SSL/UCB)

The Hopkins Ultraviolet Telescope (HUT) observed four starburst galaxies during the Astro-2 mission in 1995 March. Leitherer et al.\ (1995, ApJ 454, L19) use these data to constrain the flux emerging just below the redshifted Lyman limit, and, by comparison to the Balmer line flux, the escape fraction for ionizing photons (typically found to be less than 3%). This result has implications for the ionization of the intergalactic medium, and so merits a detailed study. Leitherer et al.\ included an extinction correction, but neglected gas phase interstellar absorption longward of 915 ÅWe have calculated the transmission of our Galaxy's interstellar medium along the four sight lines, including the effects of the H I Lyman lines and features of the more abundant elements, assuming a line-of-sight velocity distribution based on 21 cm measurements. We find that there is significant gas phase attenuation at the wavelengths of interest, loosening the constraints on the escape fraction. Quantitative results will be available by the Toronto meeting. This work is supported by NASA grant NAG5-696.

Program listing for Wednesday