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.