FARADAY ROTATION OF THE SUPERNOVA REMNANT G296.5+10.0: EVIDENCE FOR A MAGNETIZED PROGENITOR WIND
| Autor: | George Heald, Chi-Yung Ng, Roland Kothes, Lisa Harvey-Smith, Richard H. D. Townsend, Bryan Gaensler, Anne J. Green |
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| Rok vydání: | 2010 |
| Předmět: |
Physics
Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Rotation Astrophysics - Astrophysics of Galaxies law.invention Magnetic field Telescope Azimuth symbols.namesake Space and Planetary Science law Astrophysics of Galaxies (astro-ph.GA) Magnitude (astronomy) Faraday effect symbols Astrophysics::Solar and Stellar Astrophysics Red supergiant Supernova remnant Astrophysics::Galaxy Astrophysics |
| Zdroj: | The Astrophysical Journal. 712:1157-1165 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1088/0004-637x/712/2/1157 |
| Popis: | We present spectropolarimetric radio images of the supernova remnant (SNR) G296.5+10.0 at frequencies near 1.4 GHz, observed with the Australia Telescope Compact Array. By applying rotation measure (RM) synthesis to the data, a pixel-by-pixel map of Faraday rotation has been produced for the entire remnant. We find G296.5+10.0 to have a highly ordered RM structure, with mainly positive RMs (mean RM of +28 rad/m**2) on the eastern side and negative RMs (mean RM of -14 rad/m**2) on the western side, indicating a magnetic field which is directed away from us on one side and toward us on the other. We consider several possible mechanisms for creating the observed RM pattern. Neither Faraday rotation in foreground interstellar gas nor in a homogeneous ambient medium swept up by the SNR shell can easily explain the magnitude and sign of the observed RM pattern. Instead, we propose that the observed RMs are the imprint of an azimuthal magnetic field in the stellar wind of the progenitor star. Specifically, we calculate that a swept-up magnetized wind from a red supergiant can produce RMs of the observed magnitude, while the azimuthal pattern of the magnetic field at large distances from the star naturally produces the anti-symmetric RM pattern observed. Expansion into such a wind can possibly also account for the striking bilateral symmetry of the SNR's radio and X-ray morphologies. Accepted for publication in The Astrophysical Journal |
| Databáze: | OpenAIRE |
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