Stellar and Molecular Gas Rotation in a Recently-Quenched Massive Galaxy at z~0.7

TL;DR

This study investigates the gas and stellar kinematics of a massive, recently-quenched galaxy at z~0.7 to understand the mechanisms behind star formation cessation, revealing complex dynamics not fully explained by existing models.

Contribution

It provides detailed spatially resolved kinematic analysis of a post-starburst galaxy, highlighting the need for refined models of galaxy quenching processes.

Findings

Significant stellar rotation without a stellar age gradient.

Molecular gas aligned with the stellar component, no strong outflows.

Results inconsistent with simple quenching models.

Abstract

The process by which massive galaxies transition from blue, star-forming disks into red, quiescent galaxies remains one of the most poorly-understood aspects of galaxy evolution. In this investigation, we attempt to gain a better understanding of how star formation is quenched by focusing on a massive post-starburst galaxy at z = 0.747. The target has a high stellar mass and a molecular gas fraction of ~30% -- unusually high for its low star formation rate. We look for indicators of star formation suppression mechanisms in the stellar kinematics and age distribution of the galaxy obtained from spatially resolved Gemini Integral-Field spectra and in the gas kinematics obtained from ALMA. We find evidence of significant rotation in the stars, but we do not detect a stellar age gradient within 5 kpc. The molecular gas is aligned with the stellar component, and we see no evidence of strong gas outflows. Our target may represent the product of a merger-induced starburst or of morphological quenching; however, our results are not completely consistent with any of the prominent quenching models.