The origin of molecular gas outflow revealed by 10 pc - scale observation of NGC 1275

ABSTRACT :
Molecular outflows, which possibly play the role of feedback from active galactic nuclei (AGNs), are commonly detected in galaxies. As the origin of molecular outflow, it is not fully understood whether main component is gas clump blown away from the center of AGN or formed in radiatively cooling, initially hot wind. To this end, it crucial to observe the molecular outflows at the vicinity of the central engine and locate the root of them. Using ALMA band 6 data in the maximum baseline length, we obtained the HCN(3-2) and HCO+(3-2) spectra of a nearby radio/Seyfert galaxy NGC 1275. We detected blue-shifted absorption, which can be interpreted as the molecular gas outflow toward the observer. The blue-shifted absorption was also detected by previous ALMA observations, but this new data provides a tighter constraint on the location of the absorption, i.e., within the central 8 pc radius. Molecular gas cannot be created by the cooling of hot wind within such a short distance, and therefore we conclude that the molecular gas outflow is blown out from pc scale or even smaller region.