Mapping Magnetic Fields in the Cold Dust at the Galactic Center

Authors:
David T. Chuss,
Giles Novak,
Roger H. Hildebrand,
C. Darren Dowell,
John E. Vaillancourt,
Jaqueline A. Davidson,
Jessie L. Dotson

We report the detection of polarized emission in the vicinity of the Galactic
center for 158 positions within eight different pointings of the Hertz
polarimeter operating on the Caltech Submillimeter Observatory. These pointings
include positions 2 arcminutes offset to the E, NE, and NW of M-0.02-0.07;
positions to the SE and NW of the 20 km/s cloud (M-0.13-0.08), CO+0.02-0.02,
M+0.07-0.08, and M+0.11-0.08. We use these data in conjunction with previous
far-infrared and submillimeter polarization results to find that the direction
of the inferred magnetic field is related to the density of the molecular
material in the following way: in denser regions, the field is generally
parallel to the Galactic plane, whereas in regions with lower densities, the
field is generally perpendicular to the plane. This finding is consistent with
a model in which an initially poloidal field has been sheared into a toroidal
configuration in regions that are dense enough such that the gravitational
energy density is greater than the energy density of the magnetic field. Using
this model, we estimate the characteristic strength of the magnetic field in
the central 30 pc of our Galaxy to be a few mG.