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arXiv · 2505.10619

Redshift evolution of Lyman continuum escape fraction after JWST

A. Ferrara·M. Giavalisco·L. Pentericci·E. Vanzella·A. Calabrò·M. Llerena
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Abstract

The LyC escape fraction from galaxies, $f_{\rm esc}$, is strongly boosted by galactic outflows. In the Attenuation-Free Model (AFM) accounting for the properties of $z>10$ galaxies, radiation-driven outflows develop once the galaxy specific star formation rate, ${\rm sSFR} \ge {\rm sSFR}^* \approx 25\ {\rm Gyr}^{-1}$. As the cosmic sSFR increases with redshift, so does $f_{\rm esc}(z)$, which, when globally averaged, grows from 0.007 to 0.6 in $0 < z < 20$. We successfully tested the model on specific data sub-samples. Our predictions are consistent with measurements of $f_{\rm esc}$ up to $z=9.5$, and provide a physical explanation for the observed decreasing trend of the mean UV galaxy spectral slope, $\beta$, towards high-$z$.

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A. Ferrara, M. Giavalisco, L. Pentericci, E. Vanzella, A. Calabrò, M. Llerena. 2025-05-15. Redshift evolution of Lyman continuum escape fraction after JWST. https://doi.org/10.33232/001c.143600

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