A large number of narrow filaments in → radio continuum
occurring toward the → Galactic Center,
about 15 to 20 arc-minutes (some 50 parsecs in projection) north of
→ Sgr A*.
The radio Arc is the prototype of → non-thermal filaments (NTFs)
and resolves into a set of more than a dozen vertical filaments with
lengths of about 30 pc distributed symmetrically with respect to the
→ Galactic equator
(Yusef-Zadeh et al. 1984, Nature 310, 557).
Among more than 100 NTFs found in the Galactic center region, the Arc is the
only one known to show inverted spectrum with a
→ spectral index α = +0.3 (Law et al. 2008,
ApJS 177, 515, and references therein).
This implies a very hard energy spectrum of particles for a
source of → synchrotron radiation.
See also: → radio; → arc.
