Mapping the Supernovae Driven Winds of the Large Magellanic Cloud in Hα Emission I
Abstract
We present the first spectroscopically resolved Hα emission map of the Large Magellanic Cloud's (LMC) galactic wind. By combining new Wisconsin H-alpha Mapper observations (IHα ≳ 10 mR) with existing H I 21 cm emission observations, we (1) mapped the LMC's nearside galactic wind over a local standard of rest (LSR) velocity range of +50 ≤ vLSR ≤ +250 km s-1, (2) determined its morphology and extent, and (3) estimated its mass, outflow rate, and mass-loading factor. We observe Hα emission from this wind to typically 1° off the LMC's H I disk. Kinematically, we find that the diffuse gas in the warm-ionized phase of this wind persists at both low (≲100 km s-1) and high (≳100 km s-1) velocities, relative to the LMC's H I disk. Furthermore, we find that the high-velocity component spatially aligns with the most intense star-forming region, 30 Doradus. We, therefore, conclude that this high-velocity material traces an active outflow. We estimate the mass of the warm (Te ≈ 104 K) ionized phase of the nearside LMC outflow to be $\mathrm{log}\left({M}_{\mathrm{ionized}}/{M}_{\odot }\right)=7.51\pm 0.15$ for the combined low and high-velocity components. Assuming an ionization fraction of 75% and that the wind is symmetrical about the LMC disk, we estimate that its total (neutral and ionized) mass is $\mathrm{log}\left({M}_{\mathrm{total}}/{M}_{\odot }\right)=7.93$ , its mass-flow rate is ${\dot{M}}_{\mathrm{outflow}}\approx 1.43\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ , and its mass-loading factor is η ≈ 4.54. Our average mass-loading factor results are roughly a factor of 2.5 larger than previous Hα imaging and UV absorption line studies, suggesting that those studies are missing nearly half the gas in the outflows.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2021
- DOI:
- 10.3847/1538-4357/abd320
- arXiv:
- arXiv:2101.12129
- Bibcode:
- 2021ApJ...908...62C
- Keywords:
-
- Dwarf galaxies;
- Galaxy evolution;
- Interstellar medium;
- Large Magellanic Cloud;
- Circumgalactic medium;
- High-velocity clouds;
- Galactic winds;
- Stellar feedback;
- 416;
- 594;
- 847;
- 903;
- 1879;
- 735;
- 572;
- 1602;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, 9 figures