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Title: What is the physical origin of strong Lyα emission? I. Demographics of Lyα emitter structures

We present the results of structure analyses for a large sample of 426 Lyα emitters (LAEs) at z ∼ 2.2 that are observed with the Hubble Space Telescope/Advanced Camera for Surveys and WFC3-IR during deep extra-galactic legacy surveys. We confirm that the merger fraction and the average ellipticity of LAE's stellar component are 10%-30% and 0.4-0.6, respectively, that are comparable with previous study results. We successfully identify that some LAEs have a spatial offset between Lyα and stellar-continuum emission peaks, δ{sub Lyα}, by ∼2.5-4 kpc beyond our statistical errors. To uncover the physical origin of strong Lyα emission found in LAEs, we investigate the Lyα equivalent width (EW) dependences of three structural parameters: merger fraction, δ{sub Lyα}, and ellipticity of stellar distribution in the range of EW(Lyα) = 20-250 Å. Contrary to expectations, we find that the merger fraction does not significantly increase with Lyα EW. We reveal an anti-correlation between δ{sub Lyα} and EW(Lyα) using a Kolmogorov-Smirnov (K-S) test. There is a trend that the LAEs with a large Lyα EW have a small ellipticity. This is consistent with the recent theoretical claims that Lyα photons can more easily escape from face-on disks having a small ellipticity, due tomore » less inter-stellar gas along the line of sight, although our K-S test indicates that this trend is not statistically significant. Our results of Lyα-EW dependence generally support the idea that an H I column density is a key quantity determining Lyα emissivity.« less
Authors:
; ;  [1] ; ; ;  [2] ; ;  [3]
  1. Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan)
  2. Department of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan)
  3. Center for Computational Sciences, The University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)
Publication Date:
OSTI Identifier:
22357147
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 785; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; CORRELATIONS; COSMOLOGY; DENSITY; DISTRIBUTION; EMISSION; EMISSIVITY; GALAXIES; PHOTONS; RED SHIFT; TELESCOPES; UNIVERSE