Molecular outflows in starburst nuclei

Abstract

Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\ge 10^5$ (corresponding to a star formation rate (SFR)$\ge 1$ M${}_{\odot }$ yr${}^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\sim 200–1000$ cm${}^{-3}$ and scale height $z_0\ge 200(n_0/10^2{\mathrm{cm}}^{-3}{)}^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\ge 10^7$ M${}_{\odot }$ at a distance of a few hundred pc, with a speed of several tens of km s${}^{-1}$. We show that a SFR surface density of $10\le {\Sigma }_{SFR}\le 50$ M${}_{\odot }$ yr${}^{-1}$ kpc${}^{-2}$ favours the production of molecular outflows, consistent with observed values.

Accepted for publication in MNRAS, 17 pages, 18 figures

References in corpus (3)

• Before the first supernova: combined effects of HII regions and winds on molecular clouds
• Long way to go: how outflows from large galaxies propagate through the hot halo gas
• Extended HCN and HCO${}^{+}$ emission in the starburst galaxy M82

Cited by in corpus (3)

• Evolution of Molecular Clouds in the Superwind Galaxy NGC 1808 Probed by ALMA Observations
• A search for ionised gas outflows in an Halpha imaging atlas of nearby LINERs
• Radio halos of star forming galaxies