Zeeman measurements of the magnetic fields at the Galactic center

The 1667 MHz OH absorption against the continuum radio source at the Galactic center (SGR A) is employed to report Zeeman measurements of the magnetic field in the dense molecular gas in the 'circumnuclear disk' (CND). These observations with a resolution of 3 x 4 arcsec (about 0.15 pc at 8 kpc) were made with the VLA. For the absorbing OH gas identifiable with the southern part of the CND, a Zeeman splitting corresponding to B cos theta = -2.0 mG at a 7-sigma confidence level is measured. In the northern part of the CND, -2mG is again measured, but at a marginal 4-sigma level. In the other OH clouds within the central few hundred pc, 3-sigma upper limits to B cos theta are typically about 1-3 mG. These Zeeman measurements of the magnetic field strength in the neutral gas in the central region provide a direct comparison with the magnetic field strengths inferred from polarimetric measurements and place constraints on models of the Galactic center involving magnetic fields.