A Galactic Dust Devil: far-infrared observations of the Tornado Supernova Remnant candidate

• Published in: arXiv.org 2020-09
• Main Authors: Chawner, Hannah, Howard, Alex D P, Gomez, Haley L, Matsuura, Mikako, Priestley, Felix, Barlow, Mike J, De Looze, Ilse, Papageorgiou, Andreas, Marsh, Ken, Smith, Matt W L, Noriega-Crespo, Alberto, Rho, Jeonghee, Dunne, Loretta
• Format: Article
• Language: English
• Subjects: Absorptivity; Cosmic dust; Dust; Interstellar matter; Process mapping; Radio emission; Space telescopes; Supernova remnants; X ray binaries; X ray stars
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2009.08471

We present complicated dust structures within multiple regions of the candidate supernova remnant (SNR) the `Tornado' (G357.7-0.1) using observations with Spitzer and Herschel. We use Point Process Mapping, PPMAP, to investigate the distribution of dust in the Tornado at a resolution of 8", compared to the native telescope beams of 5-36". We find complex dust structures at multiple temperatures within both the head and the tail of the Tornado, ranging from 15 to 60K. Cool dust in the head forms a shell, with some overlap with the radio emission, which envelopes warm dust at the X-ray peak. Akin to the terrestrial sandy whirlwinds known as `Dust Devils', we find a large mass of dust contained within the Tornado. We derive a total dust mass for the Tornado head of 16.7 solar masses, assuming a dust absorption coefficient of kappa_300 =0.56m^2 kg^1, which can be explained by interstellar material swept up by a SNR expanding in a dense region. The X-ray, infra-red, and radio emission from the Tornado head indicate that this is a SNR. The origin of the tail is more unclear, although we propose that there is an X-ray binary embedded in the SNR, the outflow from which drives into the SNR shell. This interaction forms the helical tail structure in a similar manner to that of the SNR W50 and microquasar SS433.