Strong C iv emission from star-forming galaxies: a case for high Lyman continuum photon escape

• DOI: 10.1093/mnras/stac2742
• Publication Date: 2022-09-26T09:57:24Z
• Authors: A Saxena; E Cryer; R S Ellis; L Pentericci; A Calabrò; S Mascia; A Saldana-Lopez; D Schaerer; H Katz; M Llerena; R Amorín
• Keywords: Star (game theory)

Finding reliable indicators of Lyman continuum (LyC) photon leakage from galaxies is essential in order to infer their escape fraction the epoch reionisation, where direct measurements LyC flux are impossible. To this end, here we investigate whether strong C IV $\lambda \lambda 1548,1550$ emission rest-frame UV spectra traces conditions ripe for ample production and photons. We compile a sample 19 star-forming redshift range $z=3.1-4.6$ VANDELS survey that exhibit emission, producing stacked spectrum all major rest-UV lines clearly detected. Best-fitting spectral energy distribution models containing both stellar nebular suggest need low metallicities ($Z=0.1-0.2\,Z_\odot$), young ages ($\log(\rm{age/yr}) = 6.1-6.5$), high ionisation parameter ($\log U -2$) little no dust attenuation ($E(B-V)=0.00-0.01$). However, these unable fully reproduce observed He II line strengths. find Ly$\alpha$ peaks close systemic velocity, features indicative significant along line-of-sight. The covering fractions low-ionisation interstellar absorption also implying $\approx 0.05-0.30$, with signatures outflowing gas. Finally, IV/C III] ratios >0.75 subset individual detections consistent physical enable leakage. Overall, report multiple spectroscopic present emitting galaxies, potentially making an important tracer at $z>6$.