Here, we present a revised calculation of the emissivity of ionizing photons at z = 2.85 based on the analysis of the HST data in the HS1549 field. We estimate the comoving specific emissivity as
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following the assumptions of M13 and Nestor et al. (2013). In this expression, L is the non-ionizing UV luminosity, Φ is the non-ionizing UV luminosity function, and (FUV/FLyC)corr is the average flux-density ratio of non-ionizing to ionizing UV radiation for the entire galaxy sample, corrected for the mean IGM attenuation in the LyC spectral region.19

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To correct for absorption of LyC photons by neutral hydrogen in the IGM, we use the sample-averaged transmission values calculated in M13: tLAE = 0.44 ± 0.03 and tLBG = 0.35 ± 0.04.
 We perform this emissivity calculation separately for the main sample of spectroscopically confirmed LBGs and LAEs from M13 (using the UV luminosity functions from Reddy et al. 2008 for LBGs and Ouchi et al. 2008 for LAEs), and combine the LBG and LAE emissivities to obtain a total emissivity for star-forming galaxies. As in M13, we use the LRIS V-band to represent non-ionizing UV flux and NB3420 to represent LyC flux. The difference between our calculation and that of M13 lies in our estimation of the average flux-density ratio. Rather than estimating the average amount of foreground contamination from simulations, we instead know exactly which galaxies are contaminated based on the HST data. There were only two NB3420-detected galaxies in the M13 spectroscopic sample for which we were unable to acquire U336V606J125H160 imaging (D24 and lae4680), and for these objects we could not evaluate whether or not the NB3420 detections are due to foreground contamination. We thus calculate the emissivity twice in order to quote the full range of possible values: in one calculation we assume that MD5 is the only true LyC detection, and in the other calculation we assume that MD5, D24, and lae4680 are all true LyC-emitters. In addition to using the HST data to remove the NB3420 flux of foreground contaminants, we also use these measurements to estimate the percentage of contaminated flux in the non-ionizing UV. All objects with foreground contaminants identified through the HST imaging are blended in the LRIS V imaging, and it is impossible to isolate the uncontaminated z ∼ 2.85 flux in the LRIS V image. Thus, for each contaminated object, we decrease its LRIS V-band flux to match the fraction of uncontaminated V606 flux in the HST imaging. For objects that do not have HST U336V606J125H160imaging and are undetected in NB3420, we decrease their LRIS V-band flux to match the average fraction of uncontaminated V606 flux in the full sample of HST-imaged galaxies without NB3420 detections (99% for LBGs, 91% for LAEs). Finally, we use the same sample-averaged IGM correction to compute (FUV/FLyC)corr as described in M13, employing statistics of H i  absorbers from Rudie et al. (2013). We note that the clustering of Lyman limit systems is not taken into account in these absorber statistics, and thus the true mean IGM transmission may be slightly higher than the values presented in M13 (see, e.g., Prochaska et al. 2014).
Citation: Ouchi et al. 2008
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