Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe
The Galactic center lobe (GCL) is a ∼1° object located north of the Galactic center. In the mid-infrared, the GCL appears as two 8.0 μm filaments that roughly define an ellipse. There is strong 24 μm and radio continuum emission in the interior of the ellipse. Due to its morphology and location in t...
| Main Authors: | , , , , , , , , |
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| Format: | Journal Article |
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2024
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| Online Access: | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/96298 |
| _version_ | 1848766131101237248 |
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| author | Hurley-Walker, Natasha Anderson, Loren Luisi, M. McClure-Griffiths, N.M. Benjamin, R.A. Kuhn, M.A. Linville, D.J. Liu, B. Zucker, C. |
| author_facet | Hurley-Walker, Natasha Anderson, Loren Luisi, M. McClure-Griffiths, N.M. Benjamin, R.A. Kuhn, M.A. Linville, D.J. Liu, B. Zucker, C. |
| author_sort | Hurley-Walker, Natasha |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The Galactic center lobe (GCL) is a ∼1° object located north of the Galactic center. In the mid-infrared, the GCL appears as two 8.0 μm filaments that roughly define an ellipse. There is strong 24 μm and radio continuum emission in the interior of the ellipse. Due to its morphology and location in the sky, previous authors have argued that the GCL is created by outflows from star formation in the central molecular zone or by activity of the central black hole Sgr A*. We present images of the GCL from the GaLactic and Extragalactic All-sky Murchison Widefield Array survey in radio continuum that show thermal absorption against the Galactic center, incompatible with an interpretation of synchrotron self-absorption. Estimates of the cosmic-ray emissivity in this direction allow us to place a distance constraint on the GCL. To be consistent with standard emissivity assumptions, the GCL would be located 2 kpc away. At a distance of 8 kpc, the synchrotron background emissivity is enhanced by ∼75% in the direction of the GCL. We also present radio recombination line data from the Green Bank Telescope that constrain the electron temperature and line widths in this region, which are also more explicable if the GCL lies relatively close. |
| first_indexed | 2025-11-14T11:46:16Z |
| format | Journal Article |
| id | curtin-20.500.11937-96298 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:46:16Z |
| publishDate | 2024 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-962982024-12-17T01:39:58Z Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe Hurley-Walker, Natasha Anderson, Loren Luisi, M. McClure-Griffiths, N.M. Benjamin, R.A. Kuhn, M.A. Linville, D.J. Liu, B. Zucker, C. The Galactic center lobe (GCL) is a ∼1° object located north of the Galactic center. In the mid-infrared, the GCL appears as two 8.0 μm filaments that roughly define an ellipse. There is strong 24 μm and radio continuum emission in the interior of the ellipse. Due to its morphology and location in the sky, previous authors have argued that the GCL is created by outflows from star formation in the central molecular zone or by activity of the central black hole Sgr A*. We present images of the GCL from the GaLactic and Extragalactic All-sky Murchison Widefield Array survey in radio continuum that show thermal absorption against the Galactic center, incompatible with an interpretation of synchrotron self-absorption. Estimates of the cosmic-ray emissivity in this direction allow us to place a distance constraint on the GCL. To be consistent with standard emissivity assumptions, the GCL would be located 2 kpc away. At a distance of 8 kpc, the synchrotron background emissivity is enhanced by ∼75% in the direction of the GCL. We also present radio recombination line data from the Green Bank Telescope that constrain the electron temperature and line widths in this region, which are also more explicable if the GCL lies relatively close. 2024 Journal Article http://hdl.handle.net/20.500.11937/96298 10.3847/1538-4357/ad4d92 http://purl.org/au-research/grants/arc/FT190100231 http://creativecommons.org/licenses/by/4.0/ fulltext |
| spellingShingle | Hurley-Walker, Natasha Anderson, Loren Luisi, M. McClure-Griffiths, N.M. Benjamin, R.A. Kuhn, M.A. Linville, D.J. Liu, B. Zucker, C. Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title | Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title_full | Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title_fullStr | Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title_full_unstemmed | Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title_short | Low-frequency Absorption and Radio Recombination Line Features of the Galactic Center Lobe |
| title_sort | low-frequency absorption and radio recombination line features of the galactic center lobe |
| url | http://purl.org/au-research/grants/arc/FT190100231 http://hdl.handle.net/20.500.11937/96298 |