The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies

Abstract

Using the stellar kinematic maps and ancillary imaging data from the Sydney AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic shape of kinematically-selected samples of galaxies is inferred. We implement an efficient and optimised algorithm to fit the intrinsic shape of galaxies using an established method to simultaneously invert the distributions of apparent ellipticities and kinematic misalignments. The algorithm output compares favourably with previous studies of the intrinsic shape of galaxies based on imaging alone and our re-analysis of the ATLAS3D data. Our results indicate that most galaxies are oblate axisymmetric. We show empirically that the intrinsic shape of galaxies varies as a function of their rotational support as measured by the "spin" parameter proxy Lambda_Re. In particular, low spin systems have a higher occurrence of triaxiality, while high spin systems are more intrinsically flattened and axisymmetric. The intrinsic shape of galaxies is linked to their formation and merger histories. Galaxies with high spin values have intrinsic shapes consistent with dissipational minor mergers, while the intrinsic shape of low-spin systems is consistent with dissipationless multi-merger assembly histories. This range in assembly histories inferred from intrinsic shapes is broadly consistent with expectations from cosmological simulations.

15 pages, 11 figures, MNRAS in print

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Cited by in corpus (19)

• The SAMI Galaxy Survey: the third and final data release
• The stellar halos of ETGs in the IllustrisTNG simulations: the photometric and kinematic diversity of galaxies at large radii
• The SAMI Galaxy Survey: The internal orbital structure and mass distribution of passive galaxies from triaxial orbit-superposition Schwarzschild models
• The diverse nature and formation paths of slow rotator galaxies in the EAGLE simulations
• WISDOM Project -- X. The morphology of the molecular ISM in galaxy centres and its dependence on galaxy structure
• The SAMI Galaxy Survey: Satellite galaxies undergo little structural change during their quenching phase
• Keck Integral-Field Spectroscopy of M87 Reveals an Intrinsically Triaxial Galaxy and a Revised Black Hole Mass
• The SAMI Galaxy Survey: Mass and Environment as Independent Drivers of Galaxy Dynamics
• How nucleation and luminosity shape faint dwarf galaxies
• A SAMI and MaNGA view on the stellar kinematics of galaxies on the star-forming main sequence
• Triaxial Orbit-based Dynamical Modeling of Galaxies with Supermassive Black Holes and an Application to Massive Elliptical Galaxy NGC 1453
• Non-parametric Triaxial Deprojection of Elliptical Galaxies
• Prospects for Recovering Galaxy Intrinsic Shapes from Projected Quantities
• Merger histories of brightest group galaxies from MUSE stellar kinematics
• The MASSIVE Survey XIV -- Stellar Velocity Profiles and Kinematic Misalignments from 200 pc to 20 kpc in Massive Early-type Galaxies
• Scaling relations of z~0.25-1.5 galaxies in various environments from the morpho-kinematic analysis of the MAGIC sample
• The SAMI Galaxy Survey: The contribution of different kinematic classes to the stellar mass function of nearby galaxies
• On the application of dimensionality reduction and clustering algorithms for the classification of kinematic morphologies of galaxies
• Shapes of dark matter haloes with discrete globular cluster dynamics: The example of NGC 5128 (Centaurus A)