A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. III. Discrete multi-component population-dynamical models based on the Jeans equations

Autor(en)

Nikolay Kacharov, Mayte Alfaro-Cuello, Nadine Neumayer, Nora Lützgendorf, Laura L. Watkins, Alessandra Mastrobuono-Battisti, Sebastian Kamann, Glenn van de Ven, Anil C. Seth, Karina T. Voggel, Iskren Y. Georgiev, Ryan Leaman, Paolo Bianchini, Torsten Böker, Steffen Mieske

Abstrakt

We present comprehensive multicomponent dynamical models of M54 (NGC 6715), the nuclear star cluster of the Sagittarius (Sgr) dwarf galaxy, which is undergoing a tidal disruption in the Milky Way halo. Previous papers in this series used a large MUSE mosaic data set to identify multiple stellar populations in the system and study their kinematic differences. Here, we use Jeans-based dynamical models that fit the population properties (mean age and metallicity), spatial distributions, and kinematics simultaneously. They provide a solid physical explanation for our previous findings. Population-dynamical models deliver a comprehensive view of the whole system, and allow us to disentangle the different stellar populations. We explore their dynamical interplay and confirm our previous findings about the build-up of Sgr’s nuclear cluster via contributions from globular cluster stars, Sgr inner field stars, and in situ star formation. We explore various parameterizations of the gravitational potential and show the importance of a radially varying mass-to-light ratio for the proper treatment of the mass profile. We find a total dynamical mass within M54's tidal radius (∼75 pc) of 1.60 ± 0.07 × 10 ⁶ M _⊙ in excellent agreement with N-body simulations. Metal-poor globular cluster stars contribute about 65% of the total mass or 1.04 ± 0.05 × 10 ⁶ M _⊙. Metal-rich stars can be further divided into young and intermediate-age populations, which contribute 0.32 ± 0.02 × 10 ⁶ M _⊙ (20%) and 0.24 ± 0.02 × 10 ⁶ M _⊙ (15%), respectively. Our population-dynamical models successfully distinguish the different stellar populations in Sgr’s nucleus because of their different spatial distributions, ages, metallicities, and kinematic features.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

European Space Agency (ESA), Baltimore, Leibniz-Institut für Astrophysik Potsdam, Space Telescope Science Institute, Max-Planck-Institut für Astronomie, Observatoire de Paris, Liverpool John Moores University (LJMU), University of Utah, Université de Strasbourg, European Southern Observatory (Chile)

Journal

The Astrophysical Journal

Band

939

Anzahl der Seiten

26

ISSN

0004-637X

DOI

https://doi.org/10.3847/1538-4357/ac9280

Publikationsdatum

11-2022

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/1e18dc36-1d5a-460b-83f7-2b82031a8e42