GREEN PEA GALAXIES REVEAL SECRETS OF Lyα ESCAPE

Journal Article · Fri Apr 01 00:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/820/2/130· OSTI ID:22518527

Yang, Huan; Wang, Junxian ^[1]; Malhotra, Sangeeta; Rhoads, James E. ^[2]; Gronke, Max; Dijkstra, Mark ^[3]; Jaskot, Anne ^[4]; Zheng, Zhenya ^[5]

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1. CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China (China)
2. Arizona State University, School of Earth and Space Exploration (United States)
3. Institute of Theoretical Astrophysics, University of Oslo (Norway)
4. Smith College, Northampton, MA (United States)
5. Pontificia Universidad Católica de Chile, Santiago (Chile)

We analyze archival Lyα spectra of 12 “Green Pea” galaxies observed with the Hubble Space Telescope, model their Lyα profiles with radiative transfer models, and explore the dependence of the Lyα escape fraction on various properties. Green Pea galaxies are nearby compact starburst galaxies with [O iii] λ5007 equivalent widths (EWs) of hundreds of Å. All 12 Green Pea galaxies in our sample show Lyα lines in emission, with an Lyα EW distribution similar to high-redshift Lyα emitters. Combining the optical and UV spectra of Green Pea galaxies, we estimate their Lyα escape fractions and find correlations between Lyα escape fraction and kinematic features of Lyα profiles. The escape fraction of Lyα in these galaxies ranges from 1.4% to 67%. We also find that the Lyα escape fraction depends strongly on metallicity and moderately on dust extinction. We compare their high-quality Lyα profiles with single H i shell radiative transfer models and find that the Lyα escape fraction anticorrelates with the derived H i column densities. Single-shell models fit most Lyα profiles well, but not the ones with the highest escape fractions of Lyα. Our results suggest that low H i column density and low metallicity are essential for Lyα escape and make a galaxy an Lyα emitter.

• OSTI ID: 22518527
• Journal Information: Astrophysical Journal, Vol. 820, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
CORRELATIONS
COSMIC DUST
DENSITY
GALAXIES
LYMAN LINES
METALLICITY
RADIANT HEAT TRANSFER
RED SHIFT
SPACE
TELESCOPES
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTRA