A 100-kiloparsec wind feeding the circumgalactic medium of a massive compact galaxy

TL;DR

This study presents observations of a massive compact galaxy exhibiting an extensive multi-phase outflow spanning over 80 kiloparsecs, driven by star formation, revealing how galactic winds enrich the circumgalactic medium.

Contribution

First detailed observation of a large-scale, multi-phase outflow from a compact galaxy, linking starburst activity to circumgalactic medium enrichment.

Findings

Ionized outflow extends over 80x100 kpc with limb-brightened bipolar structure.

Neutral gas reaches 20 kpc at velocities around 1500 km/s.

Outflow driven by star formation bursts, consistent with theoretical models.

Abstract

Ninety per cent of baryons are located outside galaxies, either in the circumgalactic or intergalactic medium. Theory points to galactic winds as the primary source of the enriched and massive circumgalactic medium. Winds from compact starbursts have been observed to flow to distances somewhat greater than ten kiloparsecs, but the circumgalactic medium typically extends beyond a hundred kiloparsecs. Here we report optical integral field observations of the massive but compact galaxy SDSS J211824.06+001729.4. The oxygen [O II] lines at wavelengths of 3726 and 3729 angstroms reveal an ionized outflow spanning 80 by 100 square kiloparsecs, depositing metal-enriched gas at 10,000 kelvin through an hourglass-shaped nebula that resembles an evacuated and limb-brightened bipolar bubble. We also observe neutral gas phases at temperatures of less than 10,000 kelvin reaching distances of 20 kiloparsecs and velocities of around 1,500 kilometres per second. This multi-phase outflow is probably driven by bursts of star formation, consistent with theory.