Rho, Jeonghee;
Ravi, Aravind P;
Tram, Le Ngoc;
Hoang, Thiem;
Chastenet, Jeremy;
Millard, Matthew;
Barlow, Michael J;
... Dunne, Loretta; + view all
(2023)
Far-infrared polarization of the supernova remnant Cassiopeia A with SOFIA HAWC.
Monthly Notices of the Royal Astronomical Society
, 522
(2)
pp. 2279-2296.
10.1093/mnras/stad1094.
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Abstract
We present polarization observations of the young supernova remnant (SNR) Cas A using the High-resolution Airborne Wideband Camera-Plus (HAWC +) instrument onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The polarization map at 154 μm reveals dust grains with strong polarization fractions (5–30 per cent), supporting previous measurements made over a smaller region of the remnant at 850 μm. The 154-μm emission and the polarization signal is coincident with a region of cold dust observed in the southeastern shell and in the unshocked central ejecta. The highly polarized far-IR emission implies the grains are large (>0.14 μm) and silicate-dominated. The polarization level varies across the SNR, with an inverse correlation between the polarization degree and the intensity and smaller polarization angle dispersion for brighter SNR emission. Stronger polarization is detected between the bright structures. This may result from a higher collision rate between the gas and dust producing a lower grain alignment efficiency where the gas density is higher. We use the dust emission to provide an estimate of the magnetic field strength in Cas A using the Davis–Chandrasekhar–Fermi method. The high polarization level is direct evidence that grains are highly elongated and strongly aligned with the magnetic field of the SNR. The dust mass from the polarized region is 0.14 ± 0.04 M☉, a lower limit of the amount of dust present within the ejecta of Cas A. This result strengthens the hypothesis that core-collapse SNe are an important contributor to the dust mass in high redshift galaxies.
| Type: | Article |
|---|---|
| Title: | Far-infrared polarization of the supernova remnant Cassiopeia A with SOFIA HAWC |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad1094 |
| Publisher version: | https://doi.org/10.1093/mnras/stad1094 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Polarization, supernovae: individual: Cassiopeia A, dust, extinction, ISM: supernova remnants |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10191077 |
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