Submillimeter polarimetric observations of the Galactic Center.
NOVAK G., DOTSON J.L., DOWELL C.D., HILDEBRAND R.H., RENBARGER T. and SCHLEUNING D.A.
Abstract (from CDS):
We report the first detection of polarized submillimeter emission from the Sagittarius A region at the Galactic center. We observed three separate 2'x2' fields: one centered on the circumnuclear disk, one centered on the peak of the molecular cloud M-0.02-0.07 (also called the ``50 km.s–1 cloud''), and one centered on the peak of the molecular cloud M-0.13-0.08 (also called the ``20 km.s–1 cloud''). Linear polarization at λ=350 µm was detected in each of the three regions, at a total of 106 distinct sky positions. In the circumnuclear disk, the projected magnetic field directions that we infer from our measurements are similar to those inferred from previous far-infrared (λ=100 µm) polarimetry. In the ``curved ridge'' region of M-0.02-0.07 that has been compressed by the expansion of Sgr A East, our results show clearly the effects of this compression on the magnetic field. In M-0.13-0.08, we observe what appears to be a stretched magnetic field, as expected for this tidally sheared cloud. It has been suggested that a ``finger-like extension'' or ``streamer'' from M-0.13-0.08 is falling into the circumnuclear disk. We tentatively interpret a flaring of magnetic field lines that we see in M-0.13-0.08 as evidence that the entire cloud has a velocity component in the Galactic eastern direction, i.e., toward the circumnuclear disk. Further observations are needed to test this interpretation. We argue that polarimetry of dust emission provides a promising tool for obtaining new information on the complex dynamics of neutral gas in the Galactic center.
Galaxy: Center - Infrared: ISM: Continuum - ISM: individual (Sagittarius A) - ISM: Magnetic Fields - Polarization