Journal article
The Lyman Alpha Reference Sample XI. Efficient turbulence-driven Lyff escape and an analysis of IR, CO, and [C II]158 μm
Astronomy and astrophysics (Berlin), Vol.644, 10
11/24/2020
DOI: 10.1051/0004-6361/201936768
Abstract
Context. Lyman-alpha (Ly alpha) is the brightest emission line in star-forming galaxies. However, its interpretation in terms of physical properties is hampered by the resonant nature of Ly alpha photons. In order to remedy this complicated situation, the Lyman Alpha Reference Sample (LARS) was defined, enabling the study of Ly alpha production and escape mechanisms in 14 local star-forming galaxies.Aims. With this paper, we complement our efforts and study the global dust and (molecular) gas content as well as the properties of gas associated with photon-dominated regions. We aim to characterize the interstellar medium of LARS galaxies, allowing us to relate these newly derived properties to quantities relevant for Ly alpha escape.Methods. We observed LARS galaxies with Herschel, SOFIA, the IRAM 30m telescope, and APEX, targeting far-infrared (FIR) continuum and emission lines of [C II]158 mu m, [O I]63 mu m, [O III]88 mu m, and low-J CO lines. Using Bayesian methods we derived dust model parameters and estimated the total gas masses for all LARS galaxies, taking into account a metallicity-dependent gas-to-dust ratio. Star formation rates were estimated from FIR, [C II]158 mu m, and [O I]63 mu m luminosities.Results. LARS covers a wide dynamic range in the derived properties, with FIR-based star formation rates from similar to 0.5-100 M-circle dot yr(-1), gas fractions between similar to 15-80%, and gas depletion times ranging from a few hundred megayears up to more than ten gigayears. The distribution of LARS galaxies in the Sigma(gas) versus Sigma(SFR) (Kennicutt-Schmidt plane) is thus quite heterogeneous. However, we find that LARS galaxies with the longest gas depletion times, that is, relatively high gas surface densities (Sigma(gas)) and low star formation rate densities (Sigma(SFR)), have by far the highest Ly alpha escape fraction. A strong approximately linear relation is found between the Ly alpha escape fraction and the total gas (HI+H-2) depletion time. We argue that the Ly alpha escape in those galaxies is driven by turbulence in the star-forming gas that shifts the Ly alpha photons out of resonance close to the places where they originate. We further report on an extreme [C II]158 mu m excess in LARS 5, corresponding to similar to 14 +/- 3% of the FIR luminosity, which probably is the most extreme [C II]-to-FIR ratio observed in a galaxy (without active nucleus) to date.
Details
- Title: Subtitle
- The Lyman Alpha Reference Sample XI. Efficient turbulence-driven Lyff escape and an analysis of IR, CO, and [C II]158 μm
- Creators
- J. Puschnig - AlbaNovaM. Hayes - AlbaNovaG. Ostlin - AlbaNovaJ. Cannon - Macalester CollegeI Smirnova-Pinchukova - Max Planck Institute for AstronomyB. Husemann - Max Planck Institute for AstronomyD. Kunth - Institut d'Astrophysique de ParisJ. Bridge - University of LouisvilleE. C. Herenz - European Southern ObservatoryM. Messa - University of Massachusetts AmherstI Oteo - University of Edinburgh
- Resource Type
- Journal article
- Publication Details
- Astronomy and astrophysics (Berlin), Vol.644, 10
- Publisher
- Edp Sciences S A
- DOI
- 10.1051/0004-6361/201936768
- ISSN
- 0004-6361
- eISSN
- 1432-0746
- Number of pages
- 29
- Grant note
- Max Planck Society The University of Chicago; University of Chicago Max-Planck-Institute for Astrophysics (MPA) Swedish National Space Board (SNSB); Swedish National Space Agency (SNSA) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Institute for Advanced Study United States Naval Observatory Japanese Monbukagakusho; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Swedish Research Council 726384/Empire / European Research Council (ERC) under the European Union; European Research Council (ERC) Fermilab 131425 / Centre National d'Etudes Spatiales (CNES)/Centre National de la Recherche Scientifique (CNRS) University of Pittsburgh Los Alamos National Laboratory; United States Department of Energy (DOE) Alfred P. Sloan Foundation University of Washington Princeton University US Department of Energy; United States Department of Energy (DOE) Max-Planck-Institute for Astronomy (MPIA) New Mexico State University Japan Participation Group; Sloan Digital Sky Survey (SDSS) 50 OK 0901 / DLR; Helmholtz Association; German Aerospace Centre (DLR) Vetenskapsradet; Swedish Research Council National Science Foundation; National Science Foundation (NSF) NNA17BF53C / NASA; National Aeronautics & Space Administration (NASA) NCC5-626 / National Aeronautics and Space Administration's Earth Science Technology O ffice, Computational Technologies Project 082-14; 064-15 / European Community Johns Hopkins University
- Language
- English
- Date published
- 11/24/2020
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627243202771
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