The distribution of stellar orbits in Eagle galaxies -- the effect of mergers, gas accretion, and secular evolution

Autor(en)

Giulia Santucci, Claudia Del P. Lagos, Katherine E. Harborne, Aaron Ludlow, Katy L. Proctor, Caro Foster, Richard McDermid, Adriano Poci, Sabine Thater, Glenn van de Ven, Ling Zhu, Daniel Walo Martin

Abstrakt

The merger history of a galaxy is thought to be one of the major factors determining its internal dynamics, with galaxies having undergone different types or mergers (e.g. dry, minor or major mergers) predicted to show different dynamical properties. We study the instantaneous orbital distribution of galaxies in the Eagle simulation, colouring the orbits of the stellar particles by their stellar age, in order to understand whether stars form in particular orbits (e.g. in a thin or thick disc). We first show that Eagle reproduces well the observed stellar mass fractions in different stellar orbital families as a function of stellar mass and spin parameter at z = 0. We find that the youngest stars reside in a thin disc component that can extend to the very inner regions of galaxies, and that older stars have warmer orbits, with the oldest ones showing orbits consistent with both hot and counter-rotating classifications, which is consistent with the trend found in the Milky-Way and other disc galaxies. We also show that counter-rotating orbits trace galaxy mergers - in particular dry mergers, and that in the absence of mergers, counter-rotating orbits can also be born from highly misaligned gas accretion that leads to star formation.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Chinese Academy of Sciences (CAS), University of Western Australia, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), University of New South Wales, Macquarie University, Durham University

Journal

Monthly Notices of the Royal Astronomical Society

Band

528

Seiten

2326-2345

Anzahl der Seiten

20

ISSN

0035-8711

Publikationsdatum

02-2024

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/the-distribution-of-stellar-orbits-in-eagle-galaxies--the-effect-of-mergers-gas-accretion-and-secular-evolution(b7131bc8-6539-433f-8cf3-2335f54e719b).html