The Gaseous Blowout of the 30 Doradus Starburst Region in the LMC

Le résumé fourni par la source

Abstract Widespread galactic winds emanate from the Large Magellanic Cloud (LMC), with the 30 Doradus starburst region generating the fastest and most concentrated gas flows. We report on the gas distribution, kinematics, and ionization conditions of the near-side outflow along eight down-the-barrel sightlines using UV absorption-line observations from the Hubble Space Telescope's Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program for this region along with H i 21 cm observations from the Parkes Galactic All-Sky Survey (GASS) and Galactic Australian Square Kilometre Array Pathfinder (GASKAP) survey. We find that within Δθ ≲ 1 . ° 7 from the center of 30 Doradus, the wind reaches maximum speeds of 100–150 km s−1 from the LMC’s disk. The total integrated column densities of low ions (O i, Si ii, and Fe ii) in the blueshifted wind, up to v LSR = 150 km s−1, are highest near the center and decline radially outward. We estimate an outflow mass of M outflow, Si ii ≈ (5.7–8.6) × 105 M ⊙, outflow rate of M ̇ outflow ≳ 0.02 M ⊙ yr − 1 , and mass loading factor of η ≳ 0.10 within Δθ ≲ 0 . ° 52 from the center of 30 Doradus. The observed ion ratios—together with photoionization modeling—reveal that this wind is roughly 40%–97% photoionized. The metallicities and dust depletion patterns of the high-velocity absorbers at v LSR ≈ +120 km s−1 can be explained by either a foreground Milky Way (MW) halo cloud or an outflow from the LMC. For the high ions, Si iv and C iv are broader and kinematically offset from the low ions, suggesting turbulent mixing layers existing in the wind. Finally, our hydrodynamical simulations of the Magellanic Clouds and MW system suggest that the Magellanic Corona can protect the LMC winds from the ram pressure forces exerted by the MW’s halo.

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