Ionizing radiation from galaxies in the nearby and distant universe

Cosmic reionization, when the intergalactic medium changed from neutral to ionized at z>6 is intimately linked to the early formation and evolution of galaxies.

Escaping ionizing (Lyman continuum, LyC) radiation produced in, and escaping from, early low mass and metallicity galaxies are believed to have driven reionization.

The James Webb Telescope is now detecting many galaxies in this cosmic epoch that may represent the galaxies responsible for reionization. However, due to the opaqueness of the intergalactic medium, LyC radiation cannot be drectly observed at z>4.

In order to understand what galaxy properties may lead to LyC leakage, attention has turned to star forming galaxies with low mass and metallicity in the low redshift universe.

These analogs of the epoch of reionization galaxies allows a direct study of the escaping LyC and the conditions under which this can happen.

We here propose a detailed spatially resolved investigation of low redshift epoch of analogs to probe the structure of their interstellar medium, their ionized gas properties, star formation histories, and ultraviolet dust exctinction law to shed further light on the escape mechanisms and the implications for observed galaxies at the highest redshifts, in the epoch of reionization.

In addition, we will make use of upcoming deep JWST/MIRI  observations of the Hubble Ultra Deep Field to detect Halpha emission from EoR galaxies and indirectly constrain the ionizing photon production and escape.