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http://hdl.handle.net/20.500.12386/34605
Title: | The Orion-Taurus ridge: a synchrotron radio loop at the edge of the Orion-Eridanus superbubble | Authors: | BRACCO, Andrea PADOVANI, Marco Juan D. Soler |
Issue Date: | 2023 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 677 | First Page: | L11 | Abstract: | Large-scale synchrotron loops are recognized as the main source of diffuse radio-continuum emission in the Galaxy at intermediate and high Galactic latitudes. Their origin, however, remains rather unexplained. Using a combination of multi-frequency data in the radio band of total and polarized intensities, for the first time in this letter, we associate one arc -- hereafter, the Orion-Taurus ridge -- with the wall of the most prominent stellar-feedback blown shell in the Solar neighborhood, namely the Orion-Eridanus superbubble. We traced the Orion-Taurus ridge using 3D maps of interstellar dust extinction and column-density maps of molecular gas, $N_{\rm H_2}$. We found the Orion-Taurus ridge at a distance of 400\,pc, with a plane-of-the-sky extent of $180$\,pc. Its median $N_{\rm H_2}$ value is $(1.4^{+2.6}_{-0.6})\times 10^{21}$ cm$^{-2}$. Thanks to the broadband observations below 100 MHz of the Long Wavelength Array, we also computed the low-frequency spectral-index map of synchrotron emissivity, $\beta$, in the Orion-Taurus ridge. We found a flat distribution of $\beta$ with a median value of $-2.24^{+0.03}_{-0.02}$ that we interpreted in terms of depletion of low-energy ($<$ GeV) cosmic-ray electrons in recent supernova remnants ($10^5$ - $10^6$ yrs). Our results are consistent with plane-of-the-sky magnetic-field strengths in the Orion-Taurus ridge larger than a few tens of $\mu$G ($> 30 - 40 \,\mu$G). We report the first detection of diffuse synchrotron emission from cold-neutral, partly molecular, gas in the surroundings of the Orion-Eridanus superbubble. This observation opens a new perspective to study the multiphase and magnetized interstellar medium with the advent of future high-sensitivity radio facilities, such as the C-Band All-Sky Survey and the Square Kilometre Array. | URI: | http://hdl.handle.net/20.500.12386/34605 | URL: | https://www.aanda.org/articles/aa/full_html/2023/09/aa47283-23/aa47283-23.html | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/202347283 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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aa47283-23-1.pdf | PDF editoriale | 1.79 MB | Adobe PDF | View/Open |
2308.16663-min.pdf | postprint | 752.37 kB | Adobe PDF | View/Open |
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