GREEN PEA GALAXIES REVEAL SECRETS of Lyα ESCAPE

Huan Yang, Sangeeta Malhotra, Max Gronke, James E. Rhoads, Mark Dijkstra, Anne Jaskot, Zhenya Zheng, Junxian Wang

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article number130
JournalAstrophysical Journal
Volume820
Issue number2
DOIs
StatePublished - Apr 1 2016

Keywords

  • galaxies: high-redshift
  • galaxies: starburst
  • line: profiles
  • radiative transfer
  • ultraviolet: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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