Ionized gas velocity dispersion and multiple supernova explosions

TL;DR

This study uses 3D simulations to link high velocity dispersions in dwarf galaxies to colliding supernova shells of different ages, matching observed Hα intensity and velocity dispersion patterns.

Contribution

It demonstrates that multiple supernova explosions and shell collisions explain high velocity dispersions in dwarf galaxies, aligning simulations with observations.

Findings

High velocity dispersion (>100 km/s) results from colliding SN shells of different ages.

Simulated $I_{H ext{ extalpha}}$-$\sigma$ diagrams resemble those observed in dwarf galaxies.

Degrading spatial resolution in simulations produces results similar to real observations.

Abstract

Using 3D numerical simulations we study the evolution of the H$\alpha$ intensity and velocity dispersion for single and multiple supenova (SN) explosions. We find that the $I_{\rm H\alpha}-\sigma$ diagram obtained for simulated gas flows is similar in shape to that observed in dwarf galaxies. We conclude that colliding SN shells with significant difference in age are resposible for high velocity dispersion that reaches values high as $\simgt 100$kms$^{-1}$. Such a high velocity dispersion could be hardly got for a single SN remnant. Peaks of velocity dispersion on the $I_{\rm H\alpha}-\sigma$ diagram may correspond to several stand-alone or merged SN remnants with moderately different ages. The procedure of the spatial resolution degrading in the H$\alpha$ intensity and velocity dispersion maps makes the simulated $I_{\rm H\alpha}-\sigma$ diagrams close to those observed in dwarf galaxies not only in shape, but also quantitatively.