Star–gas misalignment in galaxies. II. Origins found from the Horizon-AGN simulation

Donghyeon J. Khim, Sukyoung K. Yi, Christophe Pichon, Yohan Dubois, Julien Devriendt, Hoseung Choi, Julia J. Bryant, Scott M. Croom

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

There have been many studies aiming to reveal the origins of the star–gas misalignment found in galaxies, but there still is a lack of understanding of the contribution from each formation channel candidate. We aim to answer the question by investigating the misaligned galaxies in the Horizon-AGN simulation. There are 27,903 galaxies of stellar mass M* > 1010Me in our sample, of which 5984 are in a group in the halo mass of M200 > 1012Me. We have identified four main formation channels of misalignment and quantified their levels of contribution: mergers (35%), interaction with nearby galaxies (23%), interaction with dense environments or their central galaxies (21%), and secular evolution, including smooth accretion from neighboring filaments (21%). We found in the simulation that the gas, rather than stars, is typically more vulnerable to dynamical disturbances; hence, misalignment formation is mainly due to the change in the rotational axis of the gas rather than stars, regardless of the origin. We have also inspected the lifetime (duration) of the misalignment. The decay timescale of the misalignment shows a strong anticorrelation with the kinematic morphology (V/σ) and the cold gas fraction of the galaxy. The misalignment has a longer lifetime in denser regions, which is linked with the environmental impact on the host galaxy. There is a substantial difference in the length of the misalignment lifetime depending on the origin, and it can be explained by the magnitude of the initial position angle offset and the physical properties of the galaxies.

Original languageEnglish
Article number27
JournalAstrophysical Journal, Supplement Series
Volume254
Issue number2
DOIs
Publication statusPublished - 2021 Jun

Bibliographical note

Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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