A ring-shaped starburst as a galactic wind-generating mechanism: Morphology, emission, and mass ejection

TL;DR

This study models how ring-shaped starbursts in galaxy nuclei influence galactic wind morphology, emission features, and mass ejection, revealing complex wind structures and filament formation that depend on starburst positioning.

Contribution

It introduces hydrodynamic simulations of ring-shaped starbursts, demonstrating their impact on wind structure and asymmetry, which differs from traditional nuclear burst models.

Findings

Ring-shaped starbursts produce more complex wind structures.

Vertical position of the starburst affects mass flux asymmetry.

Filament formation with optical emission is linked to wind interactions.

Abstract

Star formation bursts promote the ejection of material from the hosting galaxies due to the momentum and energy injected by winds from massive stars and supernova explosions. Numerical or analytical models generally consider that the mass, momentum, and energy injections result from bursts in a nuclear star formation region. However, star formation bursts have recently been observed in ring-like regions in the nuclear part of the galaxies. One example is NGC 253, which has shown a central toroidal burst and an asymmetric galactic wind observed in thermal X-ray emission. The general aim of this work is to study the effect of mechanical energy injection from stellar winds and supernova explosions in star-forming bursts distributed in rings around the nucleus of the galaxy NGC 253. Additionally, these partial objectives allow us to analyze the asymmetry of the outflows due to the bursts position as well as to study the formation of filaments with optical emission and make comparisons with recent observations of galaxies with these types of star-forming bursts. We used the hydrodynamic code AMRVAC to simulate galactic wind ejection coming from a central ring-like starburst located at different vertical positions. We showed that including a ring-shaped starburst (RSS) generates a more complex structured wind than what would be expected for a spherical starburst injection. Besides the interaction between the wind generated by the RSS and the host galaxy, it can generate dense filamentary structures with H alpha emission. The mass flux analysis of our models shows that the variation in the vertical position of the starburst can generate a variation in the mass flux of each lobe of the wind up to an order of magnitude. However, this difference is sustained only for a short period, with the flux tending to be symmetrical once it enters into a free-wind solution.