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 language | English (US) |
|---|---|
| Article number | 9 |
| Journal | Astrophysical Journal |
| Volume | 852 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2018 |
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
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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 journal › Article
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 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.
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
VL - 852
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 9
ER -