We present results from a survey for z \sim 2.85 Lyman-Continuum ( LyC ) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies .
Using a custom narrowband filter ( NB3420 ) tuned to wavelengths just below the Lyman limit at z \geq 2.82 , we probe the LyC spectral region of 49 Lyman break galaxies ( LBGs ) and 91 Ly \alpha -emitters ( LAEs ) spectroscopically confirmed at z \geq 2.82 .
Four LBGs and seven LAEs are detected in NB3420 .
Using V -band data probing the rest-frame non-ionizing UV , we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and non-ionizing UV emission and are characterized by extremely blue NB3420 - V colors , corresponding to low ratios of non-ionizing to ionizing radiation ( F _ { UV } / F _ { LyC } ) that are in tension with current stellar population synthesis models .
We measure average values of ( F _ { UV } / F _ { LyC } ) for our LBG and LAE samples , correcting for foreground galaxy contamination and HI absorption in the IGM .
We find ( F _ { UV } / F _ { LyC } ) _ { corr } ^ { LBG } = 82 \pm 45 and ( F _ { UV } / F _ { LyC } ) _ { corr } ^ { LAE } = 7.4 \pm 3.6 .
These flux-density ratios correspond respectively to relative LyC escape fractions of f _ { esc, rel } ^ { LBG } = 5 - 8 % and f _ { esc, rel } ^ { LAE } = 18 - 49 % , absolute LyC escape fractions of f _ { esc } ^ { LBG } = 1 - 2 % and f _ { esc } ^ { LAE } = 5 - 15 % , and a comoving LyC emissivity from star-forming galaxies of 8.8 - 15.0 \times 10 ^ { 24 } \mathrm { ergs } \mathrm { s } ^ { -1 } \mathrm { Hz } ^ { -1 } % \mathrm { Mpc } ^ { -3 } .
In order to study the differential properties of galaxies with and without LyC detections , we analyze narrowband Ly \alpha imaging and rest-frame near-infrared imaging , finding that while LAEs with LyC detections have lower Ly \alpha equivalent widths on average , there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections .
These preliminary results are consistent with an orientation-dependent model where LyC emission escapes through cleared paths in a patchy ISM .