Blow-away in the extreme low-mass starburst galaxy Pox 186

Nathan R. Eggen, Claudia Scarlata, Evan Skillman, Anne Jaskot

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Pox 186 is an exceptionally small dwarf starburst galaxy hosting a stellar mass of ∼105 Me. Undetected in H I (M < 106 Me) from deep 21 cm observations and with an [O III]/[O II] (5007/3727) ratio of 18.3 ± 0.11, Pox 186 is a promising candidate Lyman continuum emitter. It may be a possible analog of low-mass reionization-era galaxies. We present a spatially resolved kinematic study of Pox 186 and identify two distinct ionized gas components: a broad one with σ > 400 km s−1 and a narrow one with σ < 30 km s−1. We find strikingly different morphologies between the two components and direct evidence of outflows as seen in the high-velocity gas. Possible physical mechanisms driving the creation of high-velocity gas seen in [O III] are discussed, from outflow geometry to turbulent mixing between a hot (106 K) star-cluster wind and cooler (104 K) gas clouds. We find a modest mass-outflow rate of 0.022 Me yr−1 with a small mass-loading factor of 0.5, consistent with other low-mass galaxies. Finally, we compare the mass-loading factor of Pox 186 with extrapolations from numerical simulations and discuss possible reasons for the apparent discrepancy between them.

Original languageEnglish (US)
Article number12
JournalAstrophysical Journal
Issue number1
StatePublished - Apr 29 2021

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