We present observations of a peculiar Lyman alpha-emitting galaxy at redshift 3.344, discovered in a deep, blind spectroscopic survey for faint Lyman alpha emitters with the Magellan II telescope in the Hubble Ultra Deep Field (HUDF). The galaxy exhibits complex Lyman alpha emission, including an extended, asymmetric component that is partially suppressed by damped Lyman alpha absorption, and two spatially elongated, narrow emission features. Archival HST ACS imaging shows evidence for tidal disruption of the stellar component. This V=27 galaxy appears to give us unprecedented insights into two fundamental stages in the formation of structure at high redshift: the inflow of gas into ordinary galaxies, and the escape of ionizing radiation into the intergalactic medium. Neutral hydrogen, falling in partly in form of a narrow filament, appears to emit fluorescent Lyman alpha photons induced by the stellar ionizing flux escaping from the disturbed galaxy. The in-falling material may represent primary cold accretion or an interaction-triggered inflow. The rate of ionizing photons required by the observed Lyman alpha emission is consistent with the rate of photons produced by the observed stellar population, with roughly 50 percent of ionizing photons escaping from the immediate galaxy and encountering the in-falling gas. The observational properties of the galaxy lend support to a picture where galaxy interactions facilitate the escape of both Lyman alpha and ionizing radiation. We argue that galaxies like the present object may be common at high redshift. This galaxy may therefore be a late example of an interacting population of dwarf galaxies contributing significantly to the reionization of the universe.
Galaxy and Halo Root Systems: Fingerprints of Mass Assembly
Institute for Astronomy, University of Hawaiì at Mānoa（夏威夷大学马诺阿分校天文学研究所）；Blue Marble Space（蓝大理石空间）；UNAM, Universidad Nacional Autónoma de México, Instituto de Astronomía（墨西哥国立自治大学天文学研究所）
A study of the large-scale formation in the environment of A3266: Infalling groups, filaments, and a premerger cold front
Universität Bonn（波恩大学）；Max-Planck-Institut für Radioastronomie (MPIfR)（马克斯·普朗克射电天文研究所）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理研究所）；Ludwig-Maximilians-Universität München（慕尼黑大学）
