# Galactic Winds with MUSE: A Direct Detection of FeII* Emission from a z = 1.29 Galaxy

## TL;DR

This study uses deep MUSE observations to directly detect and spatially map FeII* emission from a galaxy at z=1.29, revealing detailed properties of galactic outflows and their morphology.

## Contribution

First spatially resolved detection and mapping of FeII* emission from an individual galaxy, providing new insights into galactic wind structures at high redshift.

## Key findings

- FeII* emission is spatially extended and aligned with the galaxy's minor axis.
- The outflow shows a bi-conical morphology with a velocity up to -400 km/s.
- FeII* emission radius exceeds that of stellar and nebular emission.

## Abstract

Emission signatures from galactic winds provide an opportunity to directly map the outflowing gas, but this is traditionally challenging because of the low surface brightness. Using deep observations (27 hours) of the Hubble Deep Field South from the Multi Unit Spectroscopic Explorer (MUSE) instrument, we identify signatures of an outflow in both emission and absorption from a spatially resolved galaxy at z = 1.29 with a stellar mass M* = 8 x 10^9 Msun, star formation rate SFR = 77 Msun/yr, and star formation rate surface brightness 1.6 Msun/kpc^2 within the [OII] half-light radius R_1/2,[OII] = 2.76 +- 0.17 kpc. From a component of the strong resonant MgII and FeII absorptions at -350 km/s, we infer a mass outflow rate that is comparable to the star formation rate. We detect non-resonant FeII* emission, at lambda 2626, 2612, 2396, and 2365, at 1.2-2.4-1.5-2.7 x 10^-18 egs s-1 cm-2 respectively. These flux ratios are consistent with the expectations for optically thick gas. By combining the four non-resonant FeII* emission lines, we spatially map the FeII* emission from an individual galaxy for the first time. The FeII* emission has an elliptical morphology that is roughly aligned with the galaxy minor kinematic axis, and its integrated half-light radius R_1/2,FeII* = 4.1 +- 0.4 kpc is 50% larger than the stellar continuum (R_1/2,* = 2.34 +- 0.17 kpc) or the [OII] nebular line. Moreover, the FeII* emission shows a blue wing extending up to -400 km/s, which is more pronounced along the galaxy minor kinematic axis and reveals a C-shaped pattern in a p-v diagram along that axis. These features are consistent with a bi-conical outflow.