2016/01/12 by Y. I. Izotov, I. Orlitova, Ivana Orlitová +7 · 285 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Redshift #Reionization #astro-ph.GA
paper · pdf · doi:10.1038/nature16456
published in Nature 529(7585), 178-180 (Nature Portfolio) · to appear in Nature on the 14th of January 2016
arxiv created 2016/01/12 · openalex publication_date 2016/01/13 · arxiv updated 2016/01/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
One of the key questions in observational cosmology is the identification of the sources responsible for ionisation of the Universe after the cosmic Dark Ages, when the baryonic matter was neutral. The currently identified distant galaxies are insufficient to fully reionise the Universe by redshift z~6, but low-mass star-forming galaxies are thought to be responsible for the bulk of the ionising radiation. Since direct observations at high redshift are difficult for a variety of reasons, one solution is to identify local proxies of this galaxy population. However, starburst galaxies at low redshifts are generally opaque to their ionising radiation. This radiation with small escape fractions of 1-3% is directly detected only in three low-redshift galaxies. Here we present far-ultraviolet observations of a nearby low-mass star-forming galaxy, J0925+1403, selected for its compactness and high excitation. The galaxy is leaking ionising radiation, with an escape fraction of ~8%. The total number of photons emitted during the starburst phase is sufficient to ionize intergalactic medium material, which is about 40 times more massive than the stellar mass of the galaxy.