What the study found
The study found that the Large Magellanic Cloud’s (LMC’s) gaseous halo, or corona, is more consistent with a first-passage orbital model than a second-passage model. In the authors’ simulations, the first-passage case matched the observed present-day velocity and column density profiles more closely.
Why the authors say this matters
The authors conclude that the gas properties of the LMC’s circumgalactic medium can be used to distinguish between first- and second-passage orbital histories. They also note that their results support the idea that the LMC has only recently approached the Milky Way for the first time.
What the researchers tested
The researchers used constrained idealized simulations of the LMC and Milky Way interaction. They combined live circumgalactic gas particles with analytic dark matter potentials and evolved them along previously published orbital trajectories representing first- and second-passage models.
What worked and what didn't
The first-passage model reproduced the observed velocity profile and column density profile of the present-day LMC corona. The second-passage model did not: the longer interaction time led to present-day velocities and column densities that were significantly lower than observations. The study reports truncation radii of 16.6 ± 0.5 kpc for the first-passage model and 5.7 kpc with asymmetric uncertainties for the second-passage model.
What to keep in mind
This summary is based on constrained idealized simulations and previously published orbital trajectories, so the findings apply within that modeled setup. The abstract does not describe additional limitations beyond the comparison of first- and second-passage scenarios.
Key points
- The LMC’s corona is better reproduced by a first-passage model than by a second-passage model.
- The first-passage simulation matched the observed velocity profile and column density profile.
- The second-passage simulation produced present-day gas velocities and column densities that were lower than observed.
- The study reports a truncation radius of 16.6 ± 0.5 kpc for the first-passage case.
- The study reports a smaller truncation radius, 5.7 kpc, for the second-passage case.
Disclosure
- Research title:
- LMC corona measurements favor a first-passage orbit
- Authors:
- Scott Lucchini, J. Han, Sapna Mishra, Andrew J. Fox
- Institutions:
- Center for Astrophysics Harvard & Smithsonian, Kavli Institute for Particle Astrophysics and Cosmology, Space Telescope Science Institute, Space Telescope Science Institute, Stanford University, Université Bourgogne Franche-Comté
- Publication date:
- 2026-04-22
- OpenAlex record:
- View
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