We present the first results of our pilot study of 8 photometrically selected Lyman continuum ( LyC ) emitting galaxy candidates from the COSMOS field and focus on their optical emission line ratios .
Observations were performed in the H and K bands using the Multi-Object Spectrometer for Infra-Red Exploration ( MOSFIRE ) instrument at the Keck Observatory , targeting the [ OII ] , H \beta , and [ OIII ] emission lines .
We find that photometrically selected LyC emitting galaxy candidates have high ionization parameters , based on their high [ OIII ] / [ OII ] ratios ( O32 ) , with an average ratio for our sample of 2.5 \pm 0.2 .
Preliminary results of our companion Low Resolution Imaging Spectrometer ( LRIS ) observations , targeting LyC and Ly \alpha , show that those galaxies with the largest O32 are typically found to also be Ly \alpha emitters .
High O32 galaxies are also found to have tentative non-zero LyC escape fractions ( f _ { esc } ( LyC ) ) based on u band photometric detections .
These results are consistent with samples of highly ionized galaxies , including confirmed LyC emitting galaxies from the literature .
We also perform a detailed comparison between the observed emission line ratios and simulated line ratios from density bounded H ii regions modeled using the photoionization code MAPPINGS V. Estimates of f _ { esc } ( LyC ) for our sample fall in the range from 0.0-0.23 and suggest possible tension with published correlations between O32 and f _ { esc } ( LyC ) , adding weight to dichotomy of arguments in the literature .
We highlight the possible effects of clumpy geometry and mergers that may account for such tension .