A titanic interstellar medium ejection from a massive starburst galaxy at redshift 1.4

TL;DR

This study reports a massive gas ejection event from a starburst galaxy at redshift 1.4, likely caused by a merger rather than feedback-driven winds, suggesting a new pathway for rapid star formation quenching.

Contribution

It provides evidence that galaxy mergers can cause rapid gas ejection, challenging the prevailing view that feedback-driven winds are the primary quenching mechanism.

Findings

Ejects 46% of molecular gas at >10,000 M_sun/yr

Detects broad red-shifted CO and [CI] components in multiple transitions

Suggests merger-driven ejection as a major quenching channel

Abstract

Feedback-driven winds from star formation or active galactic nuclei might be a relevant channel for the abrupt quenching 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 z=1.4 which is ejecting $46 \pm 13$\% of its molecular gas mass at a startling rate of $\gtrsim 10,000$ M$_{\odot}{\rm yr}^{-1}$. A broad component that is red-shifted from the galaxy emission is detected in four (low- and high-J) CO and [CI] 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.