The MASSIVE Survey - X. Misalignment between kinematic and photometric axes and intrinsic shapes of massive early-type galaxies

Irina Ene, Chung Pei Ma, Melanie Veale, Jenny E. Greene, Jens Thomas, John P. Blakeslee, Caroline Foster, Jonelle L. Walsh, Jennifer Ito, Andy D. Goulding

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


We use spatially resolved two-dimensional stellar velocity maps over a 107 × 107 arcsec2 field of view to investigate the kinematic features of 90 early-type galaxies above stellar mass 1011.5M in the MASSIVE survey. We measure the misalignment angle Ψ between the kinematic and photometric axes and identify local features such as velocity twists and kinematically distinct components. We find 46 per cent of the sample to be well aligned (Ψ < 15°), 33 per cent misaligned, and 21 per cent without detectable rotation (non-rotators). Only 24 per cent of the sample are fast rotators, the majority of which (91 per cent) are aligned, whereas 57 per cent of the slow rotators are misaligned with a nearly flat distribution ofΨ from 15° to 90°. 11 galaxies have Ψ ≳ 60° and thus exhibit minor-axis ('prolate') rotation in which the rotation is preferentially around the photometric major axis. Kinematic misalignments occur more frequently for lower galaxy spin or denser galaxy environments. Using the observed misalignment and ellipticity distributions,we infer the intrinsic shape distribution of our sample and find that MASSIVE slow rotators are consistent with being mildly triaxial, with mean axis ratios of b/a = 0.88 and c/a = 0.65. In terms of local kinematic features, 51 per cent of the sample exhibits kinematic twists of larger than 20°, and two galaxies have kinematically distinct components. The frequency of misalignment and the broad distribution of Ψ reported here suggest that the most massive early-type galaxies are mildly triaxial, and that formation processes resulting in kinematically misaligned slow rotators such as gas-poor mergers occur frequently in this mass range.

Original languageEnglish (US)
Pages (from-to)2810-2826
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Sep 11 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • CD- galaxies: evolution
  • Galaxies: elliptical and lenticular
  • Galaxies: formation
  • Galaxies: kinematics and dynamics
  • Galaxies: structure


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