Total X-Ray Emission from the LMC Observed with HaloSat
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Author/Creator ORCID
Date
2021-01-11
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Citation of Original Publication
H. Gulick et al (2021), AJ 161 57 (6pp), DOI: https://doi.org/10.3847/1538-3881/abccd0
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Subjects
Abstract
We constrain the global parameters of the Large Magellanic Cloud (LMC) by modeling the first soft X-ray (0.4–6.8 keV) observations of the entire LMC produced in a single pointing with moderate spectral resolution by the HaloSat CubeSat. These data are best fit with the sum of two thermal plasma components in collisional ionization equilibrium and a power law. We find cool (0.210 ± 0.014 keV) and hot (0.89 ± 0.14 keV) components. The total X-ray luminosity of the LMC is (1.08 ± 0.14) × 10³⁹ erg s⁻¹. X-ray binaries make up a large fraction of the emission with a luminosity of (6.0 ± 0.8) × 10³⁸ erg s⁻¹, followed by cool gas from superbubbles, supernovae, and diffuse emission with a luminosity of (3.0 ± 0.3) × 10³⁸ erg s−¹. The hot gas from star formation contributes the smallest fraction, with a luminosity of (1.9 ± 0.5) × 10³⁸ erg s⁻¹. We estimate the total volume of the cool gas to be between (0.2–1.2) × 10¹⁰ pc³ and the hot gas to be between (1.0–5) × 10⁷ pc³ for filling factors of f = 1 and 0.2. These volumes result in a total thermal energy for the cool gas between (1.4–3) × 1054 erg for electron densities of 0.017–0.04 cm⁻³, and a thermal energy for the hot gas between (1.7–4) × 10⁵³ erg for electron densities of 0.12–0.3 cm⁻³. This yields cooling timescales for the cool and hot gas of (1.5–3) × 10⁸ yr and (1.8–6) × 10⁷ yr, respectively.