A New System of Parallel Isolated Nonthermal Filaments Near the Galactic Center: Evidence for a Local Magnetic Field Gradient

T. N. LaRosa(1) T. Joseph W. Lazio, Namir E. Kassim

(1) Department of Biological and Physical Sciences, Kennesaw State University, 1000 Chastain Rd., Kennesaw, GA 30144
(2) Navy-ASEE Summer Faculty Fellow, Naval Research Laboratory
(3) Code 7213, Remote Sensing Division, Naval Research Laboratory, Washington, DC 20375-5351

Paper: ApJ, 2001 December 10, in press

EPrint Server: astro-ph/0108360


We report the discovery of a system of isolated nonthermal filaments approximately 0.5\arcdeg northwest (75 pc in projection) of Sgr A. Unlike other isolated nonthermal filaments which show subfilamentation, braiding of subfilaments, and flaring at their ends, these filaments are simple linear structures and more closely resemble the parallel bundled filaments in the Galactic center radio arc. However, the most unusual feature of these filaments is that the 20/90 cm spectral index uniformly decreases as a function of length, in contrast to all other nonthermal filaments in the Galactic center. This spectral gradient may not be due to simple particle aging but could be explained by a curved electron energy spectrum embedded in a diverging magnetic field. If so, the scale of the magnetic gradient is not consistent with a large scale magnetic field centered on Sgr A\star suggesting that this filament system is tracing a local magnetic field.

Preprints available from the authors at lazio@exeter.nrl.navy.mil , or the raw TeX (no figures) if you click here.

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