Preview

PDF 16Mb

We identify a counterpart to a Galactic supershell in diffuse radio polarization, and use this to determine the magnetic fields associated with this object. GSH 006 - 15 + 7 has perturbed the polarized emission at 2.3 GHz, as observed in the S-band Polarization All Sky Survey (S-PASS), acting as a Faraday screen. We model the Faraday rotation over the shell, and produce a map of Faraday depth over the area across it. Such models require information about the polarized emission behind the screen, which we obtain from the Wilkinson Microwave Anisotropy Probe (WMAP), scaled from 23 to 2.3 GHz, to estimate the synchrotron background behind GSH 006 - 15 + 7. Using the modelled Faraday thickness, we determine the magnitude and the plane-of-the-sky structure of the line-of-sight magnetic field in the shell. We find a peak line-of-sight field strength of |B_∥|_peak = 2.0+0.01-0.7 μG. Our measurement probes weak magnetic fields in a low-density regime (number densities of ∼ 0.4cm^-3) of the ISM, thus providing crucial information about the magnetic fields in the partially-ionized phase.

Item Type:	Refereed Article
Keywords:	radio astronomy, polarisation, magnetic fields, bubbles
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Galactic astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Dickey, JM (Professor John Dickey)
ID Code:	133227
Year Published:	2018
Web of Science® Times Cited:	3
Deposited By:	Mathematics and Physics
Deposited On:	2019-06-19
Last Modified:	2019-07-23
Downloads:	5 View Download Statistics