Escape of Lyman photons from galaxies

One of the key questions in observational cosmology is the identification of the sources responsible for cosmic
reionization. The general consensus is that a population of faint low-mass galaxies must be responsible for the
bulk of the ionizing photons. However, until recently, attempts at identifying individual galaxies showing
Lyman continuum (LyC) leakage have only found very few such galaxies, both at high and low redshifts.
We recently proposed a new indirect diagnostic for LyC leakage based on the shape of the Lyman-alpha line,
that I will first review (Verhamme+15).
A breakthrough was recently achieved by our team (Izotov et al. 2016a,b), detecting LyC emission in
low-redshift (z~0.3) luminous compact star-forming galaxies (LCGs) with high LyC escape fractions
using HST/COS observations. I will present these new results, and the Lyman-alpha emission from these galaxies,
confirming our theoretical predictions.
Finally, I will propose another complementary Lyman-alpha signature for LyC leakage, discussing theoretical predictions
on the Lyman-alpha spatial extend of LyC emitters: LyC leakers should have no/faint Lyman-alpha halos.