Sheng, Yanjun and Ting, Yuan-Sen and Xue, Xiang-Xiang and Chang, Jiang and Tian, Hao (2024) Uncovering the first-infall history of the LMC through its dynamical impact in the Milky Way halo. Monthly Notices of the Royal Astronomical Society, 534 (3). pp. 2694-2714. ISSN 0035-8711, DOI https://doi.org/10.1093/mnras/stae2259.
Full text not available from this repository.Abstract
The gravitational interactions between the LMC and the Milky Way cause dynamical perturbations in the MW halo, leading to biased distributions of stellar density and kinematics. We run 50 high-resolution N-body simulations exploring varying masses and halo shapes of the MW and LMC to study the evolution of LMC-induced perturbations. By measuring mean velocities of simulated halo stars, we identify a discontinuity between the first-infall and second-passage scenarios of the LMC's orbital history. In the first-infall, the Galactocentric latitudinal velocity hovers around 16 km s(-1) for stars at 50-100 kpc, while it subsides to about 8 km s(-1) in the second-passage scenario. We demonstrate that, this reduced perturbation magnitude in the second-passage scenario is mainly due to the short dynamical times of the Galactic inner halo and the lower velocity of the LMC during its second infall into the MW. Using a subset of similar to 1100 RR Lyrae stars located in the outer halo (50 kpc <= RGC < 100 kpc) with precise distance estimates from Gaia, we find the mean latitudinal velocity (vb) in the Galactocentric frame to be < v(b)> = 18.1 +/- 4.1 km s(-1). The observation supports the first-infall scenario with a massive LMC (similar to 2.1 x 10(11 )M(circle dot)) at infall, an oblate MW halo with a virial mass M-200 < 1.4 x 10(12 )M(circle dot) and a flattening parameter q > 0.7. Our study indicates that LMC-induced kinematic disturbances can reveal its orbital history and key characteristics, as well as those of the MW. This approach shows promise in helping determine fundamental parameters of both galaxies.
| Item Type: | Article |
|---|---|
| Funders: | Australian Research Council [Grant No: DE220101520], National Key Research & Development Program of China [Grant No: 2019YFA0405504], National Natural Science Foundation of China (NSFC) [Grant No: 11988101], CAS Project for Young Scientists in Basic Research grant [Grant No: YSBR-062], China Manned Space Project [Grant No: CMS-CSST-2021-B03], National Natural Science Foundation of China (NSFC) [Grant No: 12103062], Australian National Computational Infrastructure through the National and ANU Computational Merit Allocation Schemes [Grant No: y89] |
| Uncontrolled Keywords: | Galaxy: Kinematics and dynamics; Halo; (galaxies): Magellanic Clouds |
| Subjects: | G Geography. Anthropology. Recreation > GE Environmental Sciences |
| Divisions: | Faculty of Science > Department of Physics |
| Depositing User: | Ms. Juhaida Abd Rahim |
| Date Deposited: | 30 Oct 2025 01:09 |
| Last Modified: | 30 Oct 2025 01:09 |
| URI: | http://eprints.um.edu.my/id/eprint/46363 |
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