The extreme starburst J1044+0353 blows kpc-scale bubbles

We report the discovery of a kpc-scale lacy filamentary structure in low surface-brightness H$\alpha$ and [OIII]$\lambda 5007$ 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 ${\mathrm{S}\mathrm{B}}_{\mathrm{H}\alpha }\sim 1-2\times {10}^{-18}$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.