Ammonia masers in the Milky Way
Speaker: Yaoting Yan (DoS, NAOJ)
Abstract:
Molecular maser lines are signposts of high-mass star formation, probing the excitation and kinematics of very compact regions in the close environment of young stellar objects and providing useful targets for the measurements of trigonometric parallax and proper motions. In this talk, I will give an overview of ammonia masers in our Galaxy. It is relatively rare compared to water, OH, and methanol masers. So far, it has only been detected in 47 sources in the Milky Way. 90% are in the high-mass star-forming regions. With the Effelsberg 100-m telescope, we discovered widespread non-metastable NH3 maser emission toward 17 high-mass star-forming regions (HMSFRs) in the Milky Way. This doubles the number of known non-metastable ammonia masers in our Galaxy. I will talk about how we detected the unexpected and surprising ammonia masers in CepA, G34.26, and Sgr B2, which then led to a successful survey for searching for ammonia masers. In the end, I will also discuss the pumping scenarios and present new results from our single-dish and JVLA observations.