GALACTIC-CENTER ARC-POLARIZED PLUMES COMPLEX AT 43 GHZ

We observed the distribution of the Stokes Ir parameter and the Linear polarization in the Galactic Center Are-Polarized Plumes Complex regi on at 42.5 GHz with a newly developed 40-GHz band polarimeter equipped on the Nobeyama 45-m telescope. The Galactic Center Are at 42.5 GHz i s highly polarized up to p = 50%. The magnetic fields with a 120 '' re solution in the Galactic Center Are are well ordered and are generally along the Vertical Filaments. The spectral indices between 10 and 42. 5 GHz gradually become steeper going from the Galactic Center Are to b oth Polarized Plumes, although the complex has a flat spectrum between 2.7 and 10 GHz. The relativistic electrons may be accelerated in the Galactic Center Are and gradually drift along the poloidal magnetic fi eld toward the Polarized Plumes with synchrotron-loss. The linear rota tion of the polarization angle as the wavelength square and the depola rization properties between 10 and 42.5 GHz suggest a large internal F araday rotation, RM = - 3000 rad m(-2), in the Galactic Center Arc.