Vertical structure and kinematics of the LMC disc from SDSS/Gaia
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arXiv
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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
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2025
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| _version_ | 1866908391737131008 |
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| author | Jiménez-Arranz, Ó. Horta, D. van der Marel, R. P. Nidever, D. Laporte, C. F. P. Patel, E. Rix, H. -W. |
| author_facet | Jiménez-Arranz, Ó. Horta, D. van der Marel, R. P. Nidever, D. Laporte, C. F. P. Patel, E. Rix, H. -W. |
| contents | [Abbreviated] Context: Studies of the LMC's internal kinematics have provided a detailed view of its structure, largely by the exquisite proper motion data supplied by Gaia. However, LoS velocities are only available for a small subset of Gaia data, limiting studies of the kinematics perpendicular to the LMC disc plane. Aims: We synergise new SDSS-IV/V LoS velocity measurements with Gaia data, increasing the 5D phase-space sample by almost a factor of three. We interpret and model the vertical structure and kinematics of the LMC disc. Methods: Split our sample into different stellar types. Then examine maps of vertical velocity moments perpendicular to the LMC disc. We interpret our results within three possible scenarios: 1) time-variability in the orientation of the disc symmetry axis; 2) use of an incorrect LMC disc plane orientation; or 3) the presence of warps or twists in the LMC disc. We also present a new method to construct a continuous 3D representation of the disc from spatially-resolved measurements of its viewing angles. Results: Using young stellar populations, we identify a region in the LMC arm with highly negative v_z'; this overlaps spatially with the supershell LMC 4. Our results indicate that: 1) the LMC viewing angles may vary with time, but this cannot explain most of the structure in v_z' maps; 2) when re-deriving the LMC disc plane by minimising the RMS vertical velocity v_z' across the disc, the inclination and line-of-nodes position angle are i ~ 24 degr and Ω~ 327 degr, respectively; 3) we obtain different inclinations for the inner and outer disc regions, and a quadrupolar variation with azimuth in outer the disc. We provide 3D models of the LMC disc shape. Conclusions: The combination of SDSS-IV/V and Gaia data reveal that the LMC disc is not a flat plane in equilibrium, but that the central bar region is tilted relative to a warped outer disc. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_04616 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Vertical structure and kinematics of the LMC disc from SDSS/Gaia Jiménez-Arranz, Ó. Horta, D. van der Marel, R. P. Nidever, D. Laporte, C. F. P. Patel, E. Rix, H. -W. Astrophysics of Galaxies [Abbreviated] Context: Studies of the LMC's internal kinematics have provided a detailed view of its structure, largely by the exquisite proper motion data supplied by Gaia. However, LoS velocities are only available for a small subset of Gaia data, limiting studies of the kinematics perpendicular to the LMC disc plane. Aims: We synergise new SDSS-IV/V LoS velocity measurements with Gaia data, increasing the 5D phase-space sample by almost a factor of three. We interpret and model the vertical structure and kinematics of the LMC disc. Methods: Split our sample into different stellar types. Then examine maps of vertical velocity moments perpendicular to the LMC disc. We interpret our results within three possible scenarios: 1) time-variability in the orientation of the disc symmetry axis; 2) use of an incorrect LMC disc plane orientation; or 3) the presence of warps or twists in the LMC disc. We also present a new method to construct a continuous 3D representation of the disc from spatially-resolved measurements of its viewing angles. Results: Using young stellar populations, we identify a region in the LMC arm with highly negative v_z'; this overlaps spatially with the supershell LMC 4. Our results indicate that: 1) the LMC viewing angles may vary with time, but this cannot explain most of the structure in v_z' maps; 2) when re-deriving the LMC disc plane by minimising the RMS vertical velocity v_z' across the disc, the inclination and line-of-nodes position angle are i ~ 24 degr and Ω~ 327 degr, respectively; 3) we obtain different inclinations for the inner and outer disc regions, and a quadrupolar variation with azimuth in outer the disc. We provide 3D models of the LMC disc shape. Conclusions: The combination of SDSS-IV/V and Gaia data reveal that the LMC disc is not a flat plane in equilibrium, but that the central bar region is tilted relative to a warped outer disc. |
| title | Vertical structure and kinematics of the LMC disc from SDSS/Gaia |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2501.04616 |