Article Dans Une Revue Mon.Not.Roy.Astron.Soc. Année : 2023

Andromeda XXV -- a dwarf galaxy with a low central dark matter density

Emily J.E. Charles
  • Fonction : Auteur
Michelle L.M. Collins
  • Fonction : Auteur
R. Michael Rich
  • Fonction : Auteur
Justin I. Read
  • Fonction : Auteur
Stacy Y. Kim
  • Fonction : Auteur
Rodrigo A. Ibata
Scott C. Chapman
  • Fonction : Auteur
Eduardo Balbinot
  • Fonction : Auteur
Daniel R. Weisz
  • Fonction : Auteur

Résumé

Andromeda (And) XXV has previously been reported as a dwarf spheroidal galaxy (dSph) with little-to-no dark matter. However, the uncertainties on this result were significant. In this study, we double the number of member stars and re-derive the kinematics and mass of And XXV. We find that And XXV has a systemic velocity of νr=107.7±1.0 kms1 and a velocity dispersion of σν=4.5±1.0 kms1. With this better constrained velocity dispersion, we derive a mass contained within the half-light radius of M(r<rh)=6.9+3.22.8×106 M. This mass corresponds to a mass-to-light ratio of [M/L]rh=37+1715 M/L, demonstrating, for the first time, that And XXV has an unambiguous dark matter component. We also measure the metallicity of And XXV to be [Fe/H]=1.9±0.1 dex, which is in agreement with previous results. Finally, we extend the analysis of And XXV to include mass modelling using GravSphere. We find that And XXV has a low central dark matter density, ρDM(150pc)=2.7+1.81.6×107 Mkpc3, making And XXV a clear outlier when compared to other Local Group (LG) dSphs of the similar stellar mass. In a companion paper, we will explore whether some combination of dark matter cusp-core transformations and/or tides can explain And XXV's low density.
Fichier principal
Vignette du fichier
stad752.pdf (3) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03815558 , version 1 (16-02-2024)

Identifiants

Citer

Emily J.E. Charles, Michelle L.M. Collins, R. Michael Rich, Justin I. Read, Stacy Y. Kim, et al.. Andromeda XXV -- a dwarf galaxy with a low central dark matter density. Mon.Not.Roy.Astron.Soc., 2023, 521 (3), pp.3527-3539. ⟨10.1093/mnras/stad752⟩. ⟨hal-03815558⟩
56 Consultations
33 Téléchargements

Partager

More