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arXiv · 2406.01742

UV Cooling via O VI Emission in the Superwind of M82 Observed with the Far Ultraviolet Spectroscopic Explorer (FUSE)

Jin-Ah Kim·Haeun Chung·Carlos J. Vargas·Erika Hamden
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Abstract

We examined archival Far Ultraviolet Spectroscopic Explorer data to search for far-ultraviolet emission lines in the starburst galaxy M82. The observations were made in an outflow region that extends beyond the galactic disk. We found the O VI $\lambda\lambda$ 1032, 1038 emission lines from the galaxy's southern outflow region. The O VI lines suggest that the outflowing warm-hot gas is undergoing radiative cooling. We measured a radial velocity of $\sim$420 km s$^{-1}$ from the O VI lines, which is faster than the velocity seen in H$\alpha$ observations. The O VI $\lambda$1038 emission line seems to be blended with the C II $\lambda$1037 emission line, which has a radial velocity of $\sim$300 km s$^{-1}$, similar to what is observed in H$\alpha$ observations. The outflow medium of M82 appears to be composed of gas in multiple phases with varying temperatures and kinematics. Future spectroscopic observations in high energy regimes covering a wider spatial area are necessary to understand better the properties of the warm-hot gas medium in the outflow.

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Jin-Ah Kim, Haeun Chung, Carlos J. Vargas, Erika Hamden. 2024-06-03. UV Cooling via O VI Emission in the Superwind of M82 Observed with the Far Ultraviolet Spectroscopic Explorer (FUSE). https://arxiv.org/abs/2406.01742

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