Redshift evolution of Lyman continuum escape fraction after JWST

Abstract

The LyC escape fraction from galaxies, $f_{\mathrm{esc}}$, 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, $\mathrm{sSFR}\ge {\mathrm{sSFR}}^{\ast }\approx 25{\mathrm{Gyr}}^{-1}$. As the cosmic sSFR increases with redshift, so does $f_{\mathrm{esc}}(z)$, 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 $f_{\mathrm{esc}}$ up to $z=9.5$, and provide a physical explanation for the observed decreasing trend of the mean UV galaxy spectral slope, ${\hat{I}}^2$, towards high-$z$.

7 pages, 3 figures, published by The Open Journal of Astrophysics. Comments welcome (emailto: [email protected])