The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies

Joanna S. Bridge, Matthew Hayes, Jens Melinder, Göran Östlin, Caryl Ann Gronwall, Robin Bruce Ciardullo, Hakim Atek, John M. Cannon, Max Gronke, Lucia Guaita, Alex Hagen, Edmund Christian Herenz, Daniel Kunth, Peter Laursen, J. Miguel Mas-Hesse, Stephen A. Pardy

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
Article number9
JournalAstrophysical Journal
Volume852
Issue number1
DOIs
StatePublished - Jan 1 2018

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reference sample
dust
scattering
galaxies
halos
geometry
annuli
clumps
Hubble Space Telescope
escape
spatial resolution
envelopes
radii
photons

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Bridge, Joanna S. ; Hayes, Matthew ; Melinder, Jens ; Östlin, Göran ; Gronwall, Caryl Ann ; Ciardullo, Robin Bruce ; Atek, Hakim ; Cannon, John M. ; Gronke, Max ; Guaita, Lucia ; Hagen, Alex ; Herenz, Edmund Christian ; Kunth, Daniel ; Laursen, Peter ; Mas-Hesse, J. Miguel ; Pardy, Stephen A. / The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies. In: Astrophysical Journal. 2018 ; Vol. 852, No. 1.
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abstract = "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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Bridge, JS, Hayes, M, Melinder, J, Östlin, G, Gronwall, CA, Ciardullo, RB, Atek, H, Cannon, JM, Gronke, M, Guaita, L, Hagen, A, Herenz, EC, Kunth, D, Laursen, P, Mas-Hesse, JM & Pardy, SA 2018, 'The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies', Astrophysical Journal, vol. 852, no. 1, 9. https://doi.org/10.3847/1538-4357/aa9932

The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies. / Bridge, Joanna S.; Hayes, Matthew; Melinder, Jens; Östlin, Göran; Gronwall, Caryl Ann; Ciardullo, Robin Bruce; Atek, Hakim; Cannon, John M.; Gronke, Max; Guaita, Lucia; Hagen, Alex; Herenz, Edmund Christian; Kunth, Daniel; Laursen, Peter; Mas-Hesse, J. Miguel; Pardy, Stephen A.

In: Astrophysical Journal, Vol. 852, No. 1, 9, 01.01.2018.

Research output: Contribution to journalArticle

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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 Ann

AU - Ciardullo, Robin Bruce

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.

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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.

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