Inferring the Morphology of Stellar Distribution in TNG50: Twisted and Twisted-stretched Shapes
Abstract
We investigate the morphology of the stellar distribution (SD) in a sample of Milky Way–like galaxies in the TNG50 simulation. Using a local in shell iterative method as the main approach, we explicitly show evidence of twisting (in about 52% of halos) and stretching (in 48% of them) in real space. This is matched with the reorientation observed in the eigenvectors of the inertia tensor and gives us a clear picture of having a reoriented SD. We make a comparison between the shape profile of the dark matter (DM) halo and SD and quite remarkably see that their radial profiles are fairly close, especially at small galactocentric radii, where the stellar disk is located. This implies that the DM halo is somewhat aligned with stars in response to the baryonic potential. The level of alignment mostly decreases away from the center. We study the impact of substructures in the orbital circularity parameter. It is demonstrated that in some cases, faraway substructures are counterrotating compared with the central stars and may flip the sign of total angular momentum and thus the orbital circularity parameter. Truncating them above 150 kpc, however, retains the disky structure of the galaxy as per initial selection. Including the impact of substructures in the shape of stars, we explicitly show that their contribution is subdominant. Overlaying our theoretical results on the observational constraints from previous literature, we establish fair agreement.
Additional Information
© 2021. The American Astronomical Society. Received 2021 January 20; revised 2021 May 26; accepted 2021 June 4; published 2021 August 27. We warmly acknowledge the very insightful conversations with Sirio Belli, Charlie Conroy, Daniel Eisenstein, Rohan Naidu, Dylan Nelson, Sandro Tacchella, and Annalisa Pillepich. We also acknowledge the referee for the constructive comments that improved the quality and presentation of this manuscript. R.E. is thankful for support by the Institute for Theory and Computation (ITC) at the Center for Astrophysics (CFA). We are also thankful for the supercomputer facilities at Harvard University, where most of the simulation work was done. M.V. acknowledges support through an MIT RSC award, a Kavli Research Investment Fund, NASA ATP grant NNX17AG29G, and NSF grants AST-1814053, AST-1814259, and AST-1909831. S.B. is supported by Harvard University through the ITC Fellowship. F.M. acknowledges support through the Program "Rita Levi Montalcini" of the Italian MIUR. The TNG50 simulation was realized with computer time granted by the Gauss Centre for Supercomputing (GCS) under the GCS Large-Scale Projects GCS-DWAR on the GCS share of the supercomputer Hazel Hen at HLRS. Software: h5py (de Buyl et al. 2016), matplotlib (Hunter 2007), numpy (Van der Walt et al. 2011), pandas (McKinney et al. 2010), seaborn (Waskom et al. 2020), scipy (Oliphant 2007). Data Availability. The data that are directly related to this publication and its figures are available on reasonable request from the corresponding author. The IllustrisTNG simulations themselves are publicly available at www.tng-project.org/data (Nelson et al. 2019). The TNG50 simulation will be made public in the future as well.Attached Files
Published - Emami_2021_ApJ_918_7.pdf
Accepted Version - 2012.12284.pdf
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Additional details
- Alternative title
- Stellar Halo Morphology from TNG50: Twisted and Twisted-Stretched Halos
- Eprint ID
- 110895
- Resolver ID
- CaltechAUTHORS:20210914-225402650
- Harvard University
- Massachusetts Institute of Technology (MIT)
- Kavli Foundation
- NNX17AG29G
- NASA
- AST-1814053
- NSF
- AST-1814259
- NSF
- AST-1909831
- NSF
- Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)
- Created
-
2021-09-16Created from EPrint's datestamp field
- Updated
-
2021-09-16Created from EPrint's last_modified field
- Caltech groups
- TAPIR