The SAMI Galaxy Survey: The Internal Orbital Structure and Mass Distribution of Passive Galaxies from Triaxial Orbit-superposition Schwarzschild Models ...

• Main Authors: Santucci, G, Brough, S, Van De Sande, J, McDermid, RM, Van De Ven, G, Zhu, L, D'Eugenio, F, Bland-Hawthorn, J, Barsanti, S, Bryant, JJ, M. Croom, S, Davies, RL, Green, AW, Lawrence, JS, Lorente, NPF, Owers, MS, Poci, A, Richards, SN, Thater, S, Yi, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Astronomical Society 2022
• Subjects: 5109 Space Sciences; 51 Physical Sciences; sami
• Online Access: https://dx.doi.org/10.17863/cam.84556; https://www.repository.cam.ac.uk/handle/1810/337137

Abstract Dynamical models are crucial for uncovering the internal dynamics of galaxies; however, most of the results to date assume axisymmetry, which is not representative of a significant fraction of massive galaxies. Here, we build triaxial Schwarzschild orbit-superposition models of galaxies taken from the SAMI Galaxy Survey, in order to reconstruct their inner orbital structure and mass distribution. The sample consists of 161 passive galaxies with total stellar masses in the range 10 9.5 –10 12 M ⊙ . We find that the changes in internal structures within 1R e are correlated with the total stellar mass of the individual galaxies. The majority of the galaxies in the sample (73% ± 3%) are oblate, while 19% ± 3% are mildly triaxial and 8% ± 2% have triaxial/prolate shape. Galaxies with log M ⋆ / M ⊙ > 10.50 are more likely to be non-oblate. We find a mean dark matter fraction of f DM = 0.28 ± 0.20, within 1R e . Galaxies with higher intrinsic ellipticity (flatter) are found to have more negative ...