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Title: AN IONIZATION CONE IN THE DWARF STARBURST GALAXY NGC 5253

There are few observational constraints on how the escape of ionizing photons from starburst galaxies depends on galactic parameters. Here we report on the first major detection of an ionization cone in NGC 5253, a nearby starburst galaxy. This high-excitation feature is identified by mapping the emission-line ratios in the galaxy using [S III] {lambda}9069, [S II] {lambda}6716, and H{alpha} narrowband images from the Maryland-Magellan Tunable Filter at Las Campanas Observatory. The ionization cone appears optically thin, which suggests the escape of ionizing photons. The cone morphology is narrow with an estimated solid angle covering just 3% of 4{pi} steradians, and the young, massive clusters of the nuclear starburst can easily generate the radiation required to ionize the cone. Although less likely, we cannot rule out the possibility of an obscured active galactic nucleus source. An echelle spectrum along the minor axis shows complex kinematics that are consistent with outflow activity. The narrow morphology of the ionization cone supports the scenario that an orientation bias contributes to the difficulty in detecting Lyman continuum emission from starbursts and Lyman break galaxies.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Department of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109-1042 (United States)
  2. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
  3. Kavli Institute for Astrophysics and Space Research, MIT, Cambridge, MA 02139 (United States)
  4. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
Publication Date:
OSTI Identifier:
21565346
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 741; Journal Issue: 1; Other Information: DOI: 10.1088/2041-8205/741/1/L17
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONES; EMISSION; GALACTIC EVOLUTION; GALAXIES; IONIZATION; LYMAN LINES; MORPHOLOGY; PHOTONS; RADIANT HEAT TRANSFER BOSONS; ELEMENTARY PARTICLES; ENERGY TRANSFER; EVOLUTION; HEAT TRANSFER; MASSLESS PARTICLES