The SAMI galaxy survey: Mass and environment as independent drivers of galaxy dynamics

Jesse van de Sande*, Scott M. Croom, Joss Bland-Hawthorn, Luca Cortese, Nicholas Scott, Claudia D. P. Lagos, Francesco D'Eugenio, Julia J. Bryant, Sarah Brough, Barbara Catinella, Caroline Foster, Brent Groves, Katherine E. Harborne, Ángel R. López-Sánchez, Richard McDermid, Anne Medling, Matt S. Owers, Samuel N. Richards, Sarah M. Sweet, Sam P. Vaughan

*Corresponding author for this work

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The kinematic morphology-density relation of galaxies is normally attributed to a changing distribution of galaxy stellar masses with the local environment. However, earlier studies were largely focused on slow rotators; the dynamical properties of the overall population in relation to environment have received less attention. We use the SAMI Galaxy Survey to investigate the dynamical properties of ∼1800 early and late-type galaxies with log (M/M) > 9.5 as a function of mean environmental overdensity (Σ5) and their rank within a group or cluster. By classifying galaxies into fast and slow rotators, at fixed stellar mass above log (M/M) > 10.5, we detect a higher fraction (∼3.4σ) of slow rotators for group and cluster centrals and satellites as compared to isolated-central galaxies. We find similar results when using Σ5 as a tracer for environment. Focusing on the fast-rotator population, we also detect a significant correlation between galaxy kinematics and their stellar mass as well as the environment they are in. Specifically, by using inclination-corrected or intrinsic λRe values, we find that, at fixed mass, satellite galaxies on average have the lowest λRe,intr, isolated-central galaxies have the highest λRe,intr, and group and cluster centrals lie in between. Similarly, galaxies in high-density environments have lower mean λRe,intr values as compared to galaxies at low environmental density. However, at fixed Σ5, the mean λRe,intr differences for low and high-mass galaxies are of similar magnitude as when varying Σ5 (Δ λRe,intr ∼ 0.05, with σrandom = 0.025, and σsyst < 0.03). Our results demonstrate that after stellar mass, environment plays a significant role in the creation of slow rotators, while for fast rotators we also detect an independent, albeit smaller, impact of mass and environment on their kinematic properties.

Original languageEnglish
Pages (from-to)2307-2328
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Dec 2021

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 508, Issue 2, December 2021, Pages 2307–2328, Copyright 2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


  • cosmology: observations
  • galaxies: evolution
  • galaxies: formation
  • galaxies: kinematics and dynamics
  • galaxies: stellar content
  • galaxies: structure


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