2013/04/30 by Yoshiaki Hagiwara, Makoto Miyoshi, Akihiro Doi +1
Physics and Astronomy · #Active galactic nucleus #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Maser #Megamaser #Millimeter #RADIUS #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/2041-8205/768/2/l38
published as 2013 ApJ ,768, L38 · 6 pages, 4 figures
openalex publication_date 2013/04/30 · arxiv created 2013/05/01 · arxiv updated 2013/05/02 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the first detection of extragalactic submillimeter H 2 O maser in the 321 GHz transition toward the center of Circinus galaxy, the nearby Type 2 Seyfert using the Atacama Large Millimeter/Submillimeter Array. We find that Doppler features of the detected 321 GHz H 2 O maser straddle the systemic velocity of the galaxy as seen in the spectrum of the known 22 GHz H 2 O maser in the galaxy. By comparing the velocities of the maser features in both transitions, it can be deduced that the 321 GHz maser occurs in a region similar to that of the 22 GHz maser, where the sub-parsec-scale distribution of the 22 GHz maser was revealed by earlier very long baseline interferometry observations. The detected maser features remain unresolved at the synthesized beam of ∼0 66 (∼15 pc) and coincide with the 321 GHz continuum peak within small uncertainties. We also present a tentative detection of the highest velocity feature (redshifts up to ∼635 km s −1 ) in the galaxy. If this high-velocity feature arises from a Keplerian rotating disk well established in this galaxy, it is located at a radius of ∼0.018 pc (∼1.2 × 10 5 Schwarzschild radii), which might probe molecular material closest to the central engine.