44 GHZ CLASS I METHANOL (CH3OH) MASER SURVEY IN THE GALACTIC CENTER

Abstract

ABSTRACT We report on a large 44 GHz (70–61 A +) methanol (CH3OH) maser survey of the Galactic Center. The Karl G. Jansky Very Large Array was used to search for CH3OH maser emission covering a large fraction of the region around Sgr A. In 25 pointings, over 300 CH3OH maser sources (>10σ) were detected. The majority of the maser sources have a single peak emission spectrum with line of sight velocities that range from about −13 to 72 km s−1. Most maser sources were found to have velocities around 35−55 km s−1, closely following velocities of neighboring interacting molecular clouds (MCs). The full width at half-maximum of each individual spectral feature is very narrow (∼0.85 km s−1 on average). In the north, where Sgr A East is known to be interacting with the 50 km s−1 MC, more than 100 44 GHz CH3OH masers were detected. In addition, three other distinct concentrations of masers were found, which appear to be located closer to the interior of the interacting MCs. It is possible that a subset of masers is associated with star formation, although conclusive evidence is lacking.