On the origin of low escape fractions of ionizing radiation from massive star-forming galaxies at high redshift

Understand

The physical origin of low escape fractions of ionizing radiation derived from massive star-forming galaxies at $z\sim3$-$4$ is not well understood.

• We perform idealised disc galaxy simulations to understand how galactic properties such as metallicity and gas mass affect the escape of Lyman Continuum (LyC) photons using radiation-hydrodynamic simulations with strong stellar feedback.
• We find that the luminosity-weighted escape fraction from a metal-poor ($Z=0.002$) galaxy embedded in a halo of mass $M_h\simeq10^{11}\,M_\odot$ is $\left<f_{\rm esc}^{\rm 3D}\right>\simeq 10\,\%$.
• Roughly half of the LyC photons are absorbed within scales of 100 pc, and the other half is absorbed in the ISM ($\lesssim 2\, {\rm kpc}$).