New Constraints on the Escape Fraction at z 1
Abstract
We examine deep far-ultraviolet imaging (m_AB(1600 Å) < 29) of the Hubble Deep Field-North (HDF-N) and the Hubble Ultra Deep Field (UDF) to search for escaping Lyman continuum radiation from star-forming galaxies at z 1.3. Of the 20 galaxies sufficiently bright for possible detection in the far-UV, none are detected. Once the starburst age and intergalactic HI absorption are accounted for, we derive 3σ limits to the relative escape fractions between 0.16 < f_esc,rel < 1.0 and a stacked limit of f_esc,rel < 0.11. Our stacked limit is about equal to the average detected relative escape fraction at z 3 so deeper observations are required to determine if f_esc is evolving. We see no indication of any galaxies with a relative escape fraction near unity, as seen in individual z 3 galaxies in deep spectroscopic studies. The difference may be attributed to luminosity differences in the samples or due to the different regions of the Lyman continuum that are observed (700 Å for our study and 900 Å with spectroscopy at z 3).
- Publication:
-
American Astronomical Society Meeting Abstracts #209
- Pub Date:
- May 2007
- Bibcode:
- 2007AAS...20925205S