Disc-halo gas outflows driven by stellar clusters as seen in multiwavelength tracers

We consider the dynamics of and emission from growing superbubbles in a stratified interstellar gaseous disc driven by energy release from supernovae explosions in stellar clusters with masses M-cl= 10(5 )- 1.6 x 10(6) M-?. Supernovae are spread randomly within a sphere of r(c) = 60 pc, and inject energy episodically with a specific rate 1 / 130 M-?(-1) proportional to the star formation rate (SFR) in the cluster. Models are run for several values of SFR in the range 0.01 to 0.1 M-? yr(-1), with the corresponding average surface energy input rate similar to 0.04-0.4 erg cm(-2) s(-1). We find that the discrete energy injection by isolated SNe are more efficient in blowing superbubbles: Asymptotically they reach heights of up to 3 to 16 kpc for M-cl = 10(5) - 1.6 x 10(5) M-?, correspondingly, and stay filled with a hot and dilute plasma for at least 30 Myr. During this time, they emit X-ray, H alpha and dust infrared emission. X-ray luminosities L-X proportional to SFR3/5 that we derive here are consistent with observations in star-forming galaxies. Even though dust particles of small sizes a <= 0.03 mu m are sputtered in the interior of bubbles, larger grains still contribute considerably ensuring the bubble luminosity L-IR/ SFR similar to 5 x 10(7 )L(?) M-?(-1) yr . It is shown that the origin of the North Polar Spur in the Milky Way can be connected with activity of a cluster with the stellar mass of similar to 10(5) M-? and the SFR similar to 0.1 M-? yr(-1 )some 25-30 Myr ago. Extended luminous haloes observed in edge-on galaxies (NGC 891 as an example) can be maintained by disc spread stellar clusters of smaller masses M-& lowast; ? 10(5) M-?.

Automated summary

This study investigates the dynamics and emission of growing superbubbles in a stratified interstellar gaseous disc, driven by energy release from supernovae explosions in stellar clusters. The researchers find that discrete energy injection by isolated supernovae is more efficient in blowing superbubbles, allowing them to reach heights of up to 3 to 16 kiloparsecs and remain filled with hot and dilute plasma for at least 30 million years. The results of this study have implications for the understanding of X-ray, H alpha, and dust infrared emissions, as well as the origins of certain astronomical features. Rating: 8 out of 10.