Molecular Gas in the Halo Fuels the Growth of a Massive Cluster Galaxy at High Redshift

TL;DR

This study reveals that the Spiderweb Galaxy's growth at high redshift is fueled by a large reservoir of molecular gas in the intergalactic medium, supporting models of galaxy formation from recycled gas.

Contribution

It provides direct observational evidence of molecular gas in the halo fueling galaxy growth in a high-redshift protocluster.

Findings

Molecular gas is abundant in the galaxy's halo.

Gas has low velocity dispersion, indicating an intergalactic medium origin.

Supports the idea of galaxy formation from recycled intergalactic gas.

Abstract

The largest galaxies in the Universe reside in galaxy clusters. Using sensitive observations of carbon-monoxide, we show that the Spiderweb Galaxy -a massive galaxy in a distant protocluster- is forming from a large reservoir of molecular gas. Most of this molecular gas lies between the protocluster galaxies and has low velocity dispersion, indicating that it is part of an enriched inter-galactic medium. This may constitute the reservoir of gas that fuels the widespread star formation seen in earlier ultraviolet observations of the Spiderweb Galaxy. Our results support the notion that giant galaxies in clusters formed from extended regions of recycled gas at high redshift.