TY - JOUR
T1 - The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies
AU - Bridge, Joanna S.
AU - Hayes, Matthew
AU - Melinder, Jens
AU - Östlin, Göran
AU - Gronwall, Caryl
AU - Ciardullo, Robin
AU - Atek, Hakim
AU - Cannon, John M.
AU - Gronke, Max
AU - Guaita, Lucia
AU - Hagen, Alex
AU - Herenz, Edmund Christian
AU - Kunth, Daniel
AU - Laursen, Peter
AU - Mas-Hesse, J. Miguel
AU - Pardy, Stephen A.
N1 - Funding Information:
We thank the referee for very useful comments on this manuscript. J.S.B.acknowledges support from the Swedish Research Council (VR) through the National Science Foundation (NSF) Graduate Research Opportunities Worldwide Fellowship as well as NSF grant AST-1615526. M.H.and G.Ö.acknowledge the support of the VR and the Swedish National Space Board (SNSB). M.H.is a Fellow of the Knut and Alice Wallenberg Foundation. D.K.is supported by the Centre National d’Etudes Spatiales (CNES)/Centre National de la Recherche Scientifique (CNRS) convention 131425. J.M.M.H.is funded by the Spanish MINECO grant ESP2015-65712-C5-1-R. The Institute for Gravitation and the Cosmos is supported by the Eberly College of Science and the Office of the Senior Vice President for Research at the Pennsylvania State University. This work makes use of NASA’s Astrophysics Data System and the AstroPy Python package (Astropy Collaboration et al. 2013; Muna et al. 2016). Facilities: HST (ACS, WFC3).
Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - We examine the dust geometry and Lyα scattering in the galaxies of the Lyman Alpha Reference Sample (LARS), a set of 14 nearby (0.02 < z < 0.2) Lyα-emitting and starbursting systems with Hubble Space Telescope Lyα, Hα, and Hβ imaging. We find that the global dust properties determined by line ratios are consistent with other studies, with some of the LARS galaxies exhibiting clumpy dust media, while others of them show significantly lower Lyα emission compared to their Balmer decrement. With the LARS imaging, we present Lyα/Hα and Hα/Hβ maps with spatial resolutions as low as ∼40 pc, and use these data to show that in most galaxies, the dust geometry is best modeled by three distinct regions: a central core where dust acts as a screen, an annulus where dust is distributed in clumps, and an outer envelope where Lyα photons only scatter. We show that the dust that affects the escape of Lyα is more restricted to the galaxies' central regions, while the larger Lyα halos are generated by scattering at large radii. We present an empirical modeling technique to quantify how much Lyα scatters in the halo, and find that this "characteristic" scattering distance correlates with the measured size of the Lyα halo. We note that there exists a slight anti-correlation between the scattering distance of Lyα and global dust properties.
AB - We examine the dust geometry and Lyα scattering in the galaxies of the Lyman Alpha Reference Sample (LARS), a set of 14 nearby (0.02 < z < 0.2) Lyα-emitting and starbursting systems with Hubble Space Telescope Lyα, Hα, and Hβ imaging. We find that the global dust properties determined by line ratios are consistent with other studies, with some of the LARS galaxies exhibiting clumpy dust media, while others of them show significantly lower Lyα emission compared to their Balmer decrement. With the LARS imaging, we present Lyα/Hα and Hα/Hβ maps with spatial resolutions as low as ∼40 pc, and use these data to show that in most galaxies, the dust geometry is best modeled by three distinct regions: a central core where dust acts as a screen, an annulus where dust is distributed in clumps, and an outer envelope where Lyα photons only scatter. We show that the dust that affects the escape of Lyα is more restricted to the galaxies' central regions, while the larger Lyα halos are generated by scattering at large radii. We present an empirical modeling technique to quantify how much Lyα scatters in the halo, and find that this "characteristic" scattering distance correlates with the measured size of the Lyα halo. We note that there exists a slight anti-correlation between the scattering distance of Lyα and global dust properties.
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U2 - 10.3847/1538-4357/aa9932
DO - 10.3847/1538-4357/aa9932
M3 - Article
AN - SCOPUS:85040314349
VL - 852
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 9
ER -