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arXiv · 2209.02726

Shaken, not blown: the gentle baryonic feedback of nearby starburst dwarf galaxies

A. Marasco·F. Belfiore·G. Cresci·F. Lelli·G. Venturi·L. K. Hunt·A. Concas·A. Marconi·F. Mannucci·M. Mingozzi·A. F. McLeod·N. Kumari·S. Carniani·L. Vanzi·M. Ginolfi
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Abstract

Baryonic feedback is expected to play a key role in regulating the star formation of low-mass galaxies by producing galaxy-scale winds associated with mass-loading factors $\beta\!\sim\!1\!-\!50$. We have tested this prediction using a sample of 19 nearby systems with stellar masses $10^7\!<\!M_\star/{\rm M}_{\odot}\!<\!10^{10}$, mostly lying above the main sequence of star-forming galaxies. We used MUSE@VLT optical integral field spectroscopy to study the warm ionised gas kinematics of these galaxies via a detailed modelling of their H$\alpha$ emission line. The ionised gas is characterised by irregular velocity fields, indicating the presence of non-circular motions of a few tens of km/s within galaxy discs, but with intrinsic velocity dispersion of $40$-$60$ km/s that are only marginally larger than those measured in main-sequence galaxies. Galactic winds, defined as gas at velocities larger than the galaxy escape speed, encompass only a few percent of the observed fluxes. Mass outflow rates and loading factors are strongly dependent on $M_\star$, star formation rate (SFR), SFR surface density and specific SFR. For $M_\star$ of $10^8$ M$_\odot$ we find $\beta\simeq0.02$, which is more than two orders of magnitude smaller than the values predicted by theoretical models of galaxy evolution. In our galaxy sample, baryonic feedback stimulates a gentle gas cycle rather than causing a large-scale blow out.

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A. Marasco, F. Belfiore, G. Cresci, F. Lelli, G. Venturi, L. K. Hunt, A. Concas, A. Marconi, F. Mannucci, M. Mingozzi, A. F. McLeod, N. Kumari, S. Carniani, L. Vanzi, M. Ginolfi. 2022-09-06. Shaken, not blown: the gentle baryonic feedback of nearby starburst dwarf galaxies. https://doi.org/10.1051/0004-6361%2F202244895

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