MAGNETIC FIELD STRENGTHS IN PHOTODISSOCIATION REGIONS

• Published in: The Astrophysical journal Vol. 816; no. 1; pp. 1 - 11
• Main Authors: Balser, Dana S., Roshi, D. Anish, Jeyakumar, S., Bania, T. M., Montet, Benjamin T., Shitanishi, J. A.
• Format: Journal Article
• Language: English
• Published: United Kingdom The American Astronomical Society 01-01-2016
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; DENSITY; DISSOCIATION; EMISSION; Estimates; GHZ RANGE; H2 REGIONS; ISM: general; ISM: magnetic fields; LINE WIDTHS; LTE; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MASS; Photodissociation; PHOTOLYSIS; photon-dominated region (PDR); Radiative transfer; radio lines: ISM; RECOMBINATION; regions; Strength; TELESCOPES; ZEEMAN EFFECT
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/816/1/22

ABSTRACT We measure carbon radio recombination line (RRL) emission at 5.3 toward four H ii regions with the Green Bank Telescope to determine the magnetic field strength in the photodissociation region (PDR) that surrounds the ionized gas. Roshi suggests that the non-thermal line widths of carbon RRLs from PDRs are predominantly due to magneto-hydrodynamic waves, thus allowing the magnetic field strength to be derived. We model the PDR with a simple geometry and perform the non-LTE radiative transfer of the carbon RRL emission to solve for the PDR physical properties. Using the PDR mass density from these models and the carbon RRL non-thermal line width we estimate total magnetic field strengths of in W3 and NGC 6334A. Our results for W49 and NGC 6334D are less well constrained with total magnetic field strengths between . H i and OH Zeeman measurements of the line of sight magnetic field strength ( ), taken from the literature, are between a factor of of the lower bound of our carbon RRL magnetic field strength estimates. Since , our results are consistent with the magnetic origin of the non-thermal component of carbon RRL widths.