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Title: Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11

Abstract

Star-forming galaxies are believed to be a major source of Lyman continuum (LyC) radiation responsible for reionizing the early universe. Direct observations of escaping ionizing radiation have however been sparse and with low escape fractions. In the local universe, only 10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the epoch of reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper, we reanalyze Hubble Space Telescope ( HST )-Cosmic Origins Spectrograph (COS) spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Ly α line shape, and feedback-influenced neutral interstellar medium (ISM) properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity andmore » a residual neutral gas column density in the ionized medium high enough to be optically thick to Ly α , but low enough to be at least partly transparent to LyC and undetected in Si ii. This suggests that star formation feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium.« less

Authors:
; ; ;  [1]
  1. Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
22661336
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 837; 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; DENSITY; DISTRIBUTION; FEEDBACK; FORECASTING; GALAXIES; INTERACTIONS; IONIZATION; IONIZING RADIATIONS; LYMAN LINES; RED SHIFT; SPACE; STAR EVOLUTION; STARS; TELESCOPES; UNIVERSE

Citation Formats

Rivera-Thorsen, T. Emil, Östlin, Göran, Hayes, Matthew, and Puschnig, Johannes, E-mail: trive@astro.su.se. Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA5D0A.
Rivera-Thorsen, T. Emil, Östlin, Göran, Hayes, Matthew, & Puschnig, Johannes, E-mail: trive@astro.su.se. Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11. United States. doi:10.3847/1538-4357/AA5D0A.
Rivera-Thorsen, T. Emil, Östlin, Göran, Hayes, Matthew, and Puschnig, Johannes, E-mail: trive@astro.su.se. Wed . "Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11". United States. doi:10.3847/1538-4357/AA5D0A.
@article{osti_22661336,
title = {Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11},
author = {Rivera-Thorsen, T. Emil and Östlin, Göran and Hayes, Matthew and Puschnig, Johannes, E-mail: trive@astro.su.se},
abstractNote = {Star-forming galaxies are believed to be a major source of Lyman continuum (LyC) radiation responsible for reionizing the early universe. Direct observations of escaping ionizing radiation have however been sparse and with low escape fractions. In the local universe, only 10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the epoch of reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper, we reanalyze Hubble Space Telescope ( HST )-Cosmic Origins Spectrograph (COS) spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Ly α line shape, and feedback-influenced neutral interstellar medium (ISM) properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity and a residual neutral gas column density in the ionized medium high enough to be optically thick to Ly α , but low enough to be at least partly transparent to LyC and undetected in Si ii. This suggests that star formation feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium.},
doi = {10.3847/1538-4357/AA5D0A},
journal = {Astrophysical Journal},
number = 1,
volume = 837,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}