A massive multiphase plume of gas in Abell 2390's brightest cluster galaxy

We present new ALMA CO(2-1) observations tracing 2 . 2 x 10(10) M-circle dot of molecular gas in Abell 2390's brightest cluster galaxy, where half the gas is located in a one-sided plume extending 15 kpc out from the galaxy centre. This molecular gas has a smooth and positiv e v elocity gradient, and is receding 250 km s (-1) f aster at its f arthest point than at the galaxy centre. To constrain the plume's origin, we analyse our new observations alongside existing X-ray, optical, and radio data. We consider the possibility that the plume is a jet -driven outflow with lifting aided by jet -inflated X-ray bubbles, is a trail of gas stripped from the main galaxy by ram pressure, or is formed of more recently cooled and infalling gas. The galaxy's star formation and gas cooling rate suggest the lifespan of its molecular gas may be low compared with the plume's age - which would fa v our a recently cooled plume. Molecular gas in close proximity to the active galactic nucleus is also indicated by 250 km s (-1) wide CO(2-1) absorption against the radio core, as well as previously detected CO(1-0) and HI absorption. This absorption is optically thick and has a line -of -sight velocity towards the galaxy centre of 200 km s (-1). We discuss simple models to explain its origin.