Climbing to the top of the galactic mass ladder: evidence for frequent prolate-like rotation among the most massive galaxies - Archive ouverte HAL Access content directly
Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2018

Climbing to the top of the galactic mass ladder: evidence for frequent prolate-like rotation among the most massive galaxies

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Davor Krajnović
  • Function : Author
Mark den Brok
  • Function : Author
Raffaella Anna Marino
  • Function : Author
Kasper Borello Schmidt
  • Function : Author
Matthias Steinmetz
  • Function : Author
Peter M. Weilbacher
  • Function : Author

Abstract

We present the stellar velocity maps of 25 massive early-type galaxies located in dense environments observed with MUSE. Galaxies are selected to be brighter than MK = -25.7 mag, reside in the core of the Shapley Super Cluster or be the brightest galaxy in clusters richer than the Virgo Cluster. We thus targeted galaxies more massive than 1012 M and larger than 10 kpc (half-light radius). The velocity maps show a large variety of kinematic features: oblate-like regular rotation, kinematically distinct cores, and various types of non-regular rotation. The kinematic misalignment angles show that massive galaxies can be divided into two categories: those with small or negligible misalignment and those with misalignment consistent with being 90°. Galaxies in this latter group, comprising just under half of our galaxies, have prolate-like rotation (rotation around the major axis). Among the brightest cluster galaxies the incidence of prolate-like rotation is 50 per cent, while for a magnitude limited sub-sample of objects within the Shapley Super Cluster (mostly satellites), 35 per cent of galaxies show prolate-like rotation. Placing our galaxies on the mass-size diagram, we show that they all fall on a branch extending almost an order of magnitude in mass and a factor of 5 in size from the massive end of galaxies, previously recognized as associated with major dissipation-less mergers. The presence of galaxies with complex kinematics and, particularly, prolate-like rotators suggests, according to current numerical simulations, that the most massive galaxies grow predominantly through dissipation-less equal-mass mergers.
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Dates and versions

insu-03711221 , version 1 (02-07-2022)

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Davor Krajnović, Eric Emsellem, Mark den Brok, Raffaella Anna Marino, Kasper Borello Schmidt, et al.. Climbing to the top of the galactic mass ladder: evidence for frequent prolate-like rotation among the most massive galaxies. Monthly Notices of the Royal Astronomical Society, 2018, 477, pp.5327-5337. ⟨10.1093/mnras/sty1031⟩. ⟨insu-03711221⟩
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