SOFIA Far Infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Super-Galactic Wind

• Published in: arXiv.org 2018-12
• Main Authors: Jones, Terry Jay, Dowell, C Darren, Enrique Lopez Rodriguez, Zweibel, Ellen G, Berthoud, Marc, Chuss, David T, Goldsmith, Paul F, Hamilton, Ryan T, Hanany, Shaul, Harper, Doyal A, 7 Alex Lazarian, Looney, Leslie W, Michail, Joseph M, Morris, Mark R, Novak, Giles, Santos, Fabio P, Sheth, Kartik, Stacey, Gordon J, Staguhn, Johannes, Stephens, Ian W, Tassis, Konstantinos, Trinh, Christopher Q, Volpert, C G, Werner, Michael, Wollack, Edward J
• Format: Article
• Language: English
• Subjects: Astronomical polarimetry; Dust; Emission; Galactic winds; Geometry; Infrared astronomy; Infrared imaging; Outflow; Polarization
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1812.06816

We present Far-Infrared polarimetry observations of M82 at 53 and \(154~\mu \rm{m}\) and NGC 253 at \(89~\mu \rm{m}\), which were taken with HAWC+ in polarimetry mode on the Stratospheric Observatory for Infrared Astronomy (SOFIA). The polarization of M82 at \(53~\mu \rm{m}\) clearly shows a magnetic field geometry perpendicular to the disk in the hot dust emission. For M82 the polarization at \(154~\mu \rm{m}\) shows a combination of field geometry perpendicular to the disk in the nuclear region, but closer to parallel to the disk away from the nucleus. The fractional polarization at \(53~\mu \rm{m}\) \((154~\mu \rm{m})\) ranges from 7% (3%) off nucleus to 0.5% (0.3%) near the nucleus. A simple interpretation of the observations of M82 invokes a massive polar outflow, dragging the field along, from a region \(\sim 700\)~pc in diameter that has entrained some of the gas and dust, creating a vertical field geometry seen mostly in the hotter \((53~\mu \rm{m})\) dust emission. This outflow sits within a larger disk with a more typical planar geometry that more strongly contributes to the cooler \((154~\mu \rm{m})\) dust emission. For NGC 253, the polarization at \(89~\mu \rm{m}\) is dominated by a planar geometry in the tilted disk, with weak indication of a vertical geometry above and below the plane from the nucleus. The polarization observations of NGC 253 at \(53~\mu \rm{m}\) were of insufficient S/N for detailed analysis.