Magnetic Field Strengths in the Vicinity of Sgr A* via 18 cm Zeeman Observations

Abstract Very Large Array (VLA) observations of 18 cm OH absorption lines were used to determine the strength of the line-of-sight magnetic field in the Galactic center region. This study is an extension of the VLA OH Zeeman observations of Killeen et al. with fourfold the on-source integration time and twice the sensitivity to the Zeeman effect. The new data fail to confirm the 7 σ Zeeman detections of 2 mG fields reported in the earlier work. Also, we cannot reproduce these reported detections from our own analysis of archival data of the earlier work. We find no certain detections of the OH Zeeman effect in the Galactic center region. Our results suggest magnetic fields of no more than about a milligauss in the sampled regions.