Galactic Winds in Low-Mass Galaxies. (arXiv:1910.04167v1 [astro-ph.GA])

Galactic Winds in Low-Mass Galaxies. (arXiv:1910.04167v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+McQuinn_K/0/1/0/all/0/1">Kristen B. W. McQuinn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zee_L/0/1/0/all/0/1">Liese van Zee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Skillman_E/0/1/0/all/0/1">Evan D. Skillman</a>

Stellar-feedback driven outflows are predicted to play a fundamental role in
the baryon cycle of low-mass galaxies. However, observational constraints of
winds in nearby dwarf galaxies are limited as outflows are transient,
intrinsically low-surface brightness features, and, thus, difficult to detect.
Using deep Hapha observations, we search for winds in a sample of twelve nearby
dwarfs (M_* ~ 10^7 – 10^9.3 Msun) which host on-going or recent starbursts. We
detect features which we classify as winds in 6 galaxies, fountain candidates
in 5 galaxies, and diffuse ISM in 1 system. Winds are found preferentially in
galaxies with centrally concentrated star formation, while fountains are found
in galaxies with spatially distributed star formation. We suggest that the
concentration of star formation is a predictor for whether a low-mass galaxy
will develop a wind. The spatial extent of all detected ionized gas is limited
(<1/10 virial radius) and would still be considered the ISM by cosmological simulations. Our observations suggest that the majority of material expelled from dwarfs does not escape to the intergalactic medium but remains in the halo and may be recycled to the galaxies. Derived mass-loading factors range from 0.2-7 (with only a weak dependency on circular velocity or stellar mass), in tension with higher values in simulations needed to reproduce realistic low-mass galaxies and resolve discrepancies with LambdaCDM. The sample is part of the panchromatic STARBurst IRegular Dwarf Survey - STARBIRDS - designed to characterize the starburst phenomenon in dwarf galaxies. We also report a previously uncatalogued nearby galaxy (J1118+7913).

Stellar-feedback driven outflows are predicted to play a fundamental role in
the baryon cycle of low-mass galaxies. However, observational constraints of
winds in nearby dwarf galaxies are limited as outflows are transient,
intrinsically low-surface brightness features, and, thus, difficult to detect.
Using deep Hapha observations, we search for winds in a sample of twelve nearby
dwarfs (M_* ~ 10^7 – 10^9.3 Msun) which host on-going or recent starbursts. We
detect features which we classify as winds in 6 galaxies, fountain candidates
in 5 galaxies, and diffuse ISM in 1 system. Winds are found preferentially in
galaxies with centrally concentrated star formation, while fountains are found
in galaxies with spatially distributed star formation. We suggest that the
concentration of star formation is a predictor for whether a low-mass galaxy
will develop a wind. The spatial extent of all detected ionized gas is limited
(<1/10 virial radius) and would still be considered the ISM by cosmological
simulations. Our observations suggest that the majority of material expelled
from dwarfs does not escape to the intergalactic medium but remains in the halo
and may be recycled to the galaxies. Derived mass-loading factors range from
0.2-7 (with only a weak dependency on circular velocity or stellar mass), in
tension with higher values in simulations needed to reproduce realistic
low-mass galaxies and resolve discrepancies with LambdaCDM. The sample is part
of the panchromatic STARBurst IRegular Dwarf Survey – STARBIRDS – designed to
characterize the starburst phenomenon in dwarf galaxies. We also report a
previously uncatalogued nearby galaxy (J1118+7913).

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