ON THE DETECTION OF IONIZING RADIATION ARISING FROM STAR-FORMING GALAXIES AT REDSHIFT z ~ 3-4: LOOKING FOR ANALOGS OF "STELLAR RE-IONIZERS"

We use the spatially resolved, multi-band photometry in the GOODS South field acquired by the CANDELS project to constrain the nature of candidate Lyman continuum (LyC) emitters at redshift z ~ 3.7 identified using ultradeep imaging below the Lyman limit (1[sigma] limit of approximately 30 AB in a 2" diameter aperture). We fit the spectral energy distribution of the LyC candidates to spectral population synthesis models to measure photometric redshifts and the stellar population parameters. We also discuss the differences in the UV colors between the LBG and the LyC candidates, and how to estimate the escape fraction of ionizing radiation (f sub(esc)) in cases, like in most of our galaxies, where the LyC emission is spatially offset from the host galaxy. In all but one case we conclude that the candidate LyC emission is most likely due to lower redshift interlopers. We estimate its f sub(esc) to be in the range 25%-100%, depending on the dust and intergalactic attenuation.