2023/06/02 by Yoshiaki Hagiwara, Hagiwara, Yoshiaki, Willem A. Baan +5
Chemistry · Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Molecular Spectroscopy and Structure #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2306.01396
openalex publication_date 2023/06/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The results of high-resolution spectral-line observations of dense molecular gas are presented towards the nuclear region of the type 2 Seyfert galaxy NGC1068. MERLIN observations of the 22 GHz H2O maser were made for imaging the known off-nuclear maser emission at radio jet component located about 0.3" north-east of the radio nucleus in the galaxy. High angular resolution ALMA observations have spatially resolved the molecular gas emissions of HCN and HCO+ in this region. The off-nuclear maser spots are found to nearly overlap with a ring-like molecular gas structure and are tracing an evolving shock-like structure, which appears to be energized by interaction between the radio jet and circumnuclear medium. A dynamic jet-ISM interaction is further supported by a systematic shift of the centroid velocities of the off-nuclear maser features over a period of 35 years. The integrated flux ratios of the HCO+ line emission features at component C suggest a kinetic temperature Tk \gtrsim 300K and an H2 density of \gtrsim 106 cm-3, which are conditions where water masers may be formed. The diagnostics of the masering action in this jet-ISM interaction region is exemplary for galaxies hosting off-nuclear H2O maser emission.