October 8, 2010Open Access
A DEEPHUBBLE SPACE TELESCOPESEARCH FOR ESCAPING LYMAN CONTINUUM FLUX ATz∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY
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Abstract
We have obtained deep Hubble Space Telescope far-UV images of 15 starburst galaxies at z ~ 1. 3 in the GOODS fields to search for escaping Lyman continuum (LyC) photons. These are the deepest far-UV images (m_ (AB) = 28. 7, 3σ, 1" diameter) over this large an area (4. 83 arcmin²) and provide some of the best escape fraction constraints any galaxies at any redshift. We do not detect any individual galaxies, with 3σ limits to the LyC (~700 Å) 50–149 times fainter (in f_ν) than the rest-frame UV (1500 Å) continuum fluxes. Correcting for the mean medium (IGM) attenuation (factor ~2), as well as an intrinsic stellar Lyman break (factor ~3), these translate to relative escape fraction limits of f_ (esc, rel) 4 and reionization of the IGM at z > 6.