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http://hdl.handle.net/20.500.12386/28638
Title: | The Fan Region at 1.5 GHz - I. Polarized synchrotron emission extending beyond the Perseus Arm | Authors: | Hill, A. S. Landecker, T. L. CARRETTI, ETTORE Douglas, K. Sun, X. H. Gaensler, B. M. Mao, S. A. McClure-Griffiths, N. M. Reich, W. Wolleben, M. Dickey, J. M. Gray, A. D. Haverkorn, M. Leahy, J. P. Schnitzeler, D. H. F. M. |
Issue Date: | 2017 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 467 | Issue: | 4 | First Page: | 4631 | Abstract: | The Fan Region is one of the dominant features in the polarized radio sky, long thought to be a local (distance ≲500 pc) synchrotron feature. We present 1.3-1.8 GHz polarized radio continuum observations of the region from the Global Magneto-Ionic Medium Survey and compare them to maps of Hα and polarized radio continuum intensity from 0.408 to 353 GHz. The high-frequency (>1 GHz) and low-frequency (≲600 MHz) emissions have different morphologies, suggesting a different physical origin. Portions of the 1.5 GHz Fan Region emission are depolarized by ≈30 per cent by ionized gas structures in the Perseus Arm, indicating that this fraction of the emission originates ≳2 kpc away. We argue for the same conclusion based on the high polarization fraction at 1.5 GHz (≈40 per cent). The Fan Region is offset with respect to the Galactic plane, covering -5° ≲ b ≲ +10°; we attribute this offset to the warp in the outer Galaxy. We discuss origins of the polarized emission, including the spiral Galactic magnetic field. This idea is a plausible contributing factor although no model to date readily reproduces all of the observations. We conclude that models of the Galactic magnetic field should account for the ≳1 GHz emission from the Fan Region as a Galactic scale, not purely local, feature. | URI: | http://hdl.handle.net/20.500.12386/28638 | URL: | https://academic.oup.com/mnras/article/467/4/4631/2998726 | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stx389 | Bibcode ADS: | 2017MNRAS.467.4631H | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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stx389.pdf | Pdf editoriale | 10.97 MB | Adobe PDF | View/Open |
28638-stx389_P01.pdf | Miur | 6.27 MB | Adobe PDF | |
28638-stx389_P02.pdf | Miur | 4.78 MB | Adobe PDF |
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