Document Type
Article
Publication Date
11-20-1995
Publication Title
Astrophysical Journal
Abstract
The starburst galaxies IRAS 08339+6517, Mrk 1267, Mrk 66, and Mrk 496 (=NGC 6090) were observed with the Hopkins Ultraviolet Telescope (HUT) during the Astro-2 mission. All four galaxies have radial velocities larger than 5000 km s-1, permitting the measurement of their intrinsic Lyman continuum fluxes redward of the H I absorption edge in our Galaxy. The sample was selected on the basis of having the most favorable conditions for the escape of Lyman continuum photons. Two a upper limits of Fk < 7 X 10-16 ergs s-1 cm-2 A-1 were obtained for the flux around 900 A within the rest frame of each galaxy.A set of theoretical spectral energy distributions has been calculated. We show that there exists a tight correlation between the continuum luminosity at 900 A and the total number of photons emitted in the Lyman continuum, which is valid for high- and low-metallicity galaxies and essentially all relevant initial mass functions and star formation histories. Comparison with the observed values suggests that, on average, less than 3% of the intrinsic Lyman continuum photons escape from the program galaxies. Models for the ionization of the intergalactic medium at high 2 by young starbursts require a significant fraction of the ionizing radiation to escape from the galaxy. If the four galaxies observed by us have properties similar to young galaxies at redshift 2 2 3, such galaxies are not likely to provide Lyman continuum photons for the ionization of the early universe.
Keywords
Galaxies: ISM, Galaxies: Starburst, Intergalactic medium, Ultraviolet: Galaxies
Volume
454
Issue
1
First Page
L19
Last Page
L22
DOI
10.1086/309760
ISSN
0004637X
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
© The Authors
Recommended Citation
Leitherer, Claus; Ferguson, Henry C.; Heckman, Timothy M.; and Lowenthal, James D., "The Lyman Continuum in Starburst Galaxies Observed with the Hopkins Ultraviolet Telescope" (1995). Astronomy: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ast_facpubs/66
Comments
Archived as published.