# Launching of hot gas outflow by disc-wide supernova explosions

## TL;DR

This paper investigates how disc-wide supernova explosions can generate large-scale hot gas outflows and circulation in galaxies, depending on star formation rates and supernova distribution, with implications for observable signatures in optical and X-ray bands.

## Contribution

It demonstrates that unclustered, disc-wide supernovae can produce large-scale hot gas outflows at certain energy thresholds, expanding understanding of stellar feedback effects.

## Key findings

- Hot gas outflows occur at energy input rates above ~4×10^{-4} erg s^{-1} cm^{-2}.
- Galaxies with high star formation rates show distinct optical and X-ray signatures.
- Disc-wide supernovae can drive gas circulation within a few gas scale heights.

## Abstract

Galactic gas outflows are driven by stellar feedback with dominant contribution from supernovae (SN) explosions. The question of whether the energy deposited by SNe initiates a large scale outflow or gas circulation on smaller scales -- between discs and intermediate haloes, depends on SN rate and their distribution in space and time. We consider here gas circulation by disc-wide unclustered SNe with galactic star formation rate in the range from {$\simeq 6\times 10^{-4}$ to $\simeq 6\times 10^{-2}~M_\odot$~yr$^{-1}$~kpc$^{-2}$, corresponding to mid-to-high star formation observed in galaxies. We show that such disc-wide SN explosion regime can form circulation of warm ($T\sim 10^4$ K) and cold ($T<10^3$ K) phases within a few gas scale heights, and elevation of hot {($T>10^5$ K)} gas at higher ($z>1$ kpc) heights. We found that the threshold energy input rate for hot gas outflows with disc-wide supernovae explosions is estimated to be of the order $\sim 4\times 10^{-4}$~erg~s$^{-1}$~cm$^{-2}$. We discuss the observational manifestations of such phenomena in optical and X-ray bands. In particular, we found that for face-on galaxies with SF ($\Sigma_{_{\rm SF}}>0.02~M_\odot$~yr$^{-1}$~kpc$^{-2}$), the line profiles of ions typical for warm gas show a double-peak shape, corresponding to out-of-plane outflows. In the X-ray bands, galaxies with high SF rates ($\Sigma_{_{\rm SF}}>0.006~M_\odot$~yr$^{-1}$~kpc$^{-2}$) can be bright, with a smooth surface brightness in low-energy bands ($0.1\hbox{--}0.3$~keV) and patchy at higher energies ($1.6\hbox{--}8.3$~keV).}