The extreme starburst J1044+0353 blows kpc-scale bubbles

TL;DR

This paper reports the discovery of large, kpc-scale shell structures around a low-metallicity, starburst galaxy, revealing complex feedback processes that challenge existing models of super-bubble evolution.

Contribution

It presents the first detailed observation of giant shell structures in a low-metallicity starburst galaxy, highlighting complexities in super-bubble dynamics.

Findings

Identification of seven elliptical Hα arcs as giant shells

Shell radii of 3-3.5 kpc larger than typical dwarf galaxy shells

Expansion velocities around 40 km/s inferred from line broadening

Abstract

We report the discovery of a kpc-scale lacy filamentary structure in low surface-brightness H$\alpha$ and [OIII]$\lambda5007$ emission around the low-redshift, extremely metal-poor and compact reionisation-era analogue SDSS J1044+0353. We identify seven elliptical arcs in H$\alpha$ emission at $\mathrm{SB}_\mathrm{H\alpha} \sim 1 - 2 \times 10^{-18}$erg s$^{-1}$cm$^{-2}$arcsec$^{-2}$. We interpret these features as limb-brightened giant-shells that bound egg-shaped super bubbles with 3-3.5 kpc radii. These shells are significantly larger than the known giant shells around nearby star-forming dwarfs. Kinematic maps reveal a gradient perpendicular to the major-axis and line broadening in the outskirts. The latter, when interpreted due to line-splitting of the expanding shells, suggests expansion velocities of $\sim 40$km s$^{-1}$. Notably, the properties of the giant shells evade description by simple analytic prescriptions for energy- and momentum-driven super-bubbles.