Large gas inflow driven by a matured galactic bar in the early Universe

TL;DR

This study presents the first kinematic evidence of a galactic bar at redshift 2.467, demonstrating that bar-driven gas inflow and secular evolution occurred over 11 billion years ago, influencing early galaxy growth.

Contribution

It provides the first detailed kinematic analysis of a high-redshift galactic bar, revealing its role in gas inflow and galaxy evolution in the early Universe.

Findings

The bar in galaxy J0107a exhibits gas dynamics similar to local bars.

The bar drives gas into the galaxy center at approximately 600 solar masses per year.

Bar-driven processes were active 11.1 billion years ago, affecting early galaxy evolution.

Abstract

Bar structures are present in about half of local disk galaxies and play pivotal roles in secular galaxy evolution. Bars impose a non-axisymmetric perturbation to the rotating disk and transport gas inward to feed central starburst and, possibly, the activity of the nuclear supermassive black hole. They are believed to be long-lived structures and are now identified at redshift $z>2$. Yet, little is known about the onset and effect of bars in the early cosmic epoch because spectroscopy of distant bars at sufficient resolution is prohibitively expensive. Here, we report a kinematic study of a galactic bar at redshift 2.467, 2.6 billion years after the Big Bang. We observe the carbon monoxide and atomic carbon emission lines of the dusty star-forming galaxy J0107a and find the bar of J0107a has gas distribution and motion in a pattern identical to local bars. At the same time, the bar drives large-scale non-circular motions that dominate over disk rotation, funneling molecular gas into its center at a rate of $\approx600$ solar masses per year. Our results show that bar-driven dynamical processes and secular evolution were already at play 11.1 billion years ago, powering active star formation amid the gas-rich and far-infrared luminous growth phase in a massive disk galaxy.