Tracing Outflows from Stellar Feedback in the Early Universe with Lyman-$\alpha$

TL;DR

This study investigates outflows from early universe star-forming galaxies using Lyman-alpha emission and JWST imaging, revealing young, low-metallicity populations with some evidence of outflows, but limited constraints on older stars.

Contribution

It provides spectroscopic confirmation of outflows in high-redshift galaxies and analyzes their star formation histories with combined HST and JWST data, highlighting their youth and low metallicity.

Findings

Detection of blueshifted interstellar absorption lines indicating outflows.

Most galaxies characterized by very young, low metallicity stellar populations.

Limited ability to constrain the mass of older stars despite JWST coverage.

Abstract

Blind spectroscopy of massive lensing galaxy clusters with MUSE has revealed large numbers of gravitationally-lensed Lyman-$ \alpha $ emitters exhibiting asymmetric profiles at $ 2.9 \leq z \leq 6.7 $, suggesting abundant outflows from low-mass star-forming galaxies in the early universe. Are these primaeval galaxies experiencing their first bursts of star formation, or established galaxies experiencing rejuvenation? With JWST rest-frame optical/NIR continuum imaging now available for many of these objects, we can search for older stellar populations. Here, we search for spectroscopic confirmation of outflows from these galaxies, finding a few high-signal-to-noise cases in which blueshifted interstellar absorption lines are detected. Next, we analyse the star formation histories with combined HST + JWST photometry. We find most them to be well characterised by very young, low metallicity stellar populations. However, despite the rest-frame optical/NIR coverage of JWST, we cannot place strict upper bounds on the mass in old stars (age $ > 100\,\text{Myr} $).