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

Kacharov, N; Alfaro-Cuello, M; Neumayer, N; Lützgendorf, N; Watkins, LL; Mastrobuono-Battisti, A; Kamann, S; van de Ven, G; Seth, AC; Voggel, KT; Georgiev, IY; Leaman, R; Bianchini, P; Böker, T; Mieske, S

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

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Kacharov, N, Alfaro-Cuello, M, Neumayer, N, Lützgendorf, N, Watkins, LL, Mastrobuono-Battisti, A, Kamann, S, van de Ven, G, Seth, AC, Voggel, KT, Georgiev, IY, Leaman, R, Bianchini, P, Böker, T and Mieske, S (2022) 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. The Astrophysical Journal, 939 (2). ISSN 1538-4357

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

Open Access URL: https://doi.org/10.3847/1538-4357/ac9280 (Published version)

Abstract

We present comprehensive multi-component dynamical models of M 54 (NGC 6715), the nuclear star cluster of the Sagittarius dwarf galaxy (Sgr), which is undergoing a tidal disruption in the Milky Way halo. Previous papers in the 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 to our previous findings. The 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 parameterisations 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 M 54’s tidal radius (∼ 75 pc) of 1.60±0.07×106 M in excellent agreement with N-body simulations. The metal-poor globular cluster stars contribute about 65% of the total mass or 1.04 ± 0.05 × 106 M. The metal-rich stars can be further divided into young and intermediate age populations that contribute 0.32±0.02×106 M (20%) and 0.24±0.02×106 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.

Item Type:	Article
Uncontrolled Keywords:	astro-ph.GA; astro-ph.GA
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society; IOP Publishing
Related URLs:	http://arxiv.org/abs/2209.06229v1
Date of acceptance:	12 September 2022
Date of first compliant Open Access:	18 November 2022
Date Deposited:	23 Sep 2022 09:12
Last Modified:	18 Nov 2022 11:00
DOI or ID number:	10.3847/1538-4357/ac9280
URI:	https://researchonline.ljmu.ac.uk/id/eprint/17659

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