Escape of ionizing radiation from galaxies
Séminaire IPAG de Ivana Orlitova (IPAG & Astronomical Institute of the Czech Academy of Sciences), jeudi 6 septembre 2018 à 11h00, salle Manuel Forestini
Reionization of the universe in the first billion years of its history represented a major change. However, the sources that caused it are still being debated. Quasars may have been too rare in that epoch, while star-forming galaxies face the problem of inefficient ionizing radiation escape : the fraction that can escape into the intergalactic medium depends on the structure of the interstellar medium. I will present a rare class of nearby star-forming galaxies, known as green peas, which resemble high-redshift objects and for which we have detected ionizing radiation leakage. We study their optical, ultraviolet and X-ray properties to understand the parameters that control the radiation escape, and we search for reliable indicators that would help finding the leakage in the reionization era. The Lyman-alpha line of hydrogen is a promising tool.