Can the ubiquitous [CII] λ157.74 μm line be used to trace warmer molecular gas and be a sign of effective AGN feedback?

The evolution of a galaxy and its central supermassive black hole (SMBH) appear to be linked through not just a galaxy's merger history, but also through interactions that take place between processes associated with black hole growth. Growing SMBHs are among a few physical mechanisms potentially capable of quenching star-formation in massive galaxies. There is strong evidence that powerful, radio-loud active galactic nuclei (AGN) can quench star-formation. Independent of their merger stage, galaxies that host AGN have excess H2 to other coolant compared to galaxies without an AGN. The ubiquitous [CII] λ157.74 μm line has been used to track CO-dark gas, estimate star-formation properties, look for obscured multi-phase outflows, and find highly turbulent nascent galaxies. We are using data from the Stratospheric Observatory for Infrared Astronomy (SOFIA) data archive to test if extended CII morphologies, complex velocity profiles, and high [CIII]/FIR ratios correlate with the presence of shocked molecular gas. Recent SOFIA observations of [CII] in nearby low-luminosity AGN suggest that: high ratios of [CII] to FIR may be associated with obscured AGN outflows and that the [CIII] may be at the interface between warm and cold gas in those outflows. Future work will include combining this observational data with state-of-the-art simulations of nebular and molecular lines to understand if higher [CII]/FIR ratios and [CII] disturbed kinematics correspond to galaxies with warmer molecular gas and could be a sign of effective AGN feedback. Our eventual goal is to expand our sample to include a total of 200 AGN.