Speaker
Description
Detailed studies of the composition, kinematics and physical conditions of cold gas in extreme irradiated and shocked environments, such as close to an active galactic nucleus (AGN), provide new insights into the chemical pathways which are not observed in other environments. I will present the discovery of an unusually strong absorption feature at a rest frequency of ~97.88 GHz in a radio-loud AGN 4C 31.04. We identify this line to be either CH3CH2CN (6-1) (Ethyl Cyanide) or CH3SH (31-30) (Methyl Mercaptan). We also find other absorption and emission lines from Ethyl Cyanide at rest frequencies ~116.5 GHz and ~98.5 GHz respectively, suggesting that the line at 97.88 GHz is very likely Ethyl cyanide. We also detect strong HI, CO and CN absorption lines. Intriguingly, generally expected transitions of other molecules such as CH3OH, SO2 and CS are absent, suggesting a very different chemistry in this case than that observed in the central molecular zone of the Galaxy, or hot cores in nearby star-forming regions. Based on pc-scale atomic gas observations, we conclude that the molecular absorption arises from a highly turbulent circumnuclear gas with which the radio jets of 4C 31.04 are interacting strongly, driving an outflow. Irrespective of the identification of the line, we find a significant abundance enhancement of many orders of magnitude for the Complex Organic Molecule (COM) giving rise to this absorption (≥0.001). This is the first time that such a COM is detected in the circumnuclear disc of a radio AGN. We suggest that its unexpectedly high gas-phase abundance so close to the active SMBH is likely due to shocks or cosmic rays driven by the radio jets. This discovery potentially presents a new challenge to existing chemical models regarding the production and sustenance of such COMs in extreme environments.
