Alice L. Argon | Searcharxiv

arXiv2005

Full-Polarization Observations of OH Masers in Massive Star-Forming Regions: I. Data

We present full-polarization VLBA maps of the ground-state, main-line, 2 Pi 3/2, J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the first large polarization survey of interstellar hydroxyl masers at VLBI resolution. A total of 184 Zeeman pairs are identified, and the corresponding magnetic field strengths are indicated. We also present spectra of the NH3 emission or absorption in these star-forming regions. Analysis of these data will be presented in a companion paper.

astro-ph↗

arXiv2003

Interstellar Hydroxyl Masers in the Galaxy. II. Zeeman Pairs and the Galactic Magnetic Field

We have identified and classified Zeeman pairs in the survey by Argon, Reid, & Menten of massive star-forming regions with 18 cm (2 Pi 3/2, J = 3/2) OH maser emission. We have found a total of more than 100 Zeeman pairs in more than 50 massive star-forming regions. The magnetic field deduced from the Zeeman splitting has allowed us to assign an overall line-of-sight magnetic field direction to many of the massive star-forming regions. Combining these data with other data sets obtained from OH Zeeman splitting, we have looked for correlations of magnetic field directions between star-forming regions scattered throughout the Galaxy. Our data do not support a uniform, Galactic-scale field direction, nor do we find any strong evidence of magnetic field correlations within spiral arms. However, our data suggest that in the Solar neighborhood the magnetic field outside the Solar circle is oriented clockwise as viewed from the North Galactic Pole, while inside the Solar circle it is oriented counterclockwise. This pattern, including the magnetic field reversal near the Sun, is in agreement with results obtained from pulsar rotation measures.

astro-ph↗