Copyright © 2021, The Author(s), under exclusive licence to Springer Nature LimitedPuglisi, A.Daddi, E.Brusa, M.Bournaud, F.Fensch, J.Liu, D.Delvecchio, I.Calabrò, A.Circosta, C.Valentino, F.Perna, M.Jin, S.Enia, A.Mancini, C.Rodighiero, G.2022-02-142022-02-142021-01-11Nature Astronomy 5: 319-330(2021)http://hdl.handle.net/20.500.12666/540The ALMA data analysed in this study are publicly available from the ALMA archive (http://almascience.nrao.edu/aq/, Program IDs: 2015.1.00260.S, 2016.1.00171.S and 2019.1.01702.S). The DEIMOS spectrum of the source is also publicly available and can be retrieved through the COSMOS archive (http://cosmos.astro.caltech.edu/).Feedback-driven winds from star formation or active galactic nuclei might be a relevant channel for the abrupt quenching of star formation in massive galaxies. However, both observations and simulations support the idea that these processes are non-conflictingly co-evolving and self-regulating. Furthermore, evidence of disruptive events that are capable of fast quenching is rare, and constraints on their statistical prevalence are lacking. Here we present a massive starburst galaxy at redshift z = 1.4, which is ejecting 46 ± 13% of its molecular gas mass at a startling rate of ≳10,000 M⊙ yr−1. A broad component that is red-shifted from the galaxy emission is detected in four (low and high J) CO and [C I] transitions and in the ionized phase, which ensures a robust estimate of the expelled gas mass. The implied statistics suggest that similar events are potentially a major star-formation quenching channel. However, our observations provide compelling evidence that this is not a feedback-driven wind, but rather material from a merger that has been probably tidally ejected. This finding challenges some literature studies in which the role of feedback-driven winds might be overstated.engGalaxies and clustersInterstellar mediuminfo:eu-repo/semantics/article10.1038/s41550-020-01268-x2397-3366http://dx.doi.org/10.13039/501100000271http://dx.doi.org/10.13039/501100000780info:eu-repo/semantics/restrictedAccess