A new technique for finding galaxies leaking Lyman-continuum radiation: [SII]-deficiency

Understand

The source responsible for the reionization of the Universe is believed to be the population of star-forming galaxies at $z\sim6$ to 12.

• The biggest uncertainty concerns the fraction of Lyman-continuum photons that actually escape from the galaxies.
• In recent years, several relatively small samples of "leaky" galaxies have been uncovered, and clues have begun to emerge as to both the indirect signposts of leakiness and of the conditions/processes that enable the escape of ionizing radiation.
• In this paper we present the results of a pilot program aimed to test a new technique for finding leaky galaxies---using the weakness of the [SII] nebular emission-lines relative to typical star-forming galaxies as evidence that the interstellar medium is optically-thin to the Lyman continuum.