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Andromeda XXV – a dwarf galaxy with a low central dark matter density.
- Source :
-
Monthly Notices of the Royal Astronomical Society . May2023, Vol. 521 Issue 3, p3527-3539. 13p. - Publication Year :
- 2023
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Abstract
- 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 nearly 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 kms−1 and a velocity dispersion of |$\sigma _{\rm \nu }=3.7^{+1.2}_{-1.1}$|  kms−1. With this updated velocity dispersion and a new literature measurement of the radial surface brightness profile, we derive a mass contained within the half-light radius of |$M(r\lt r_{\rm h})=4.7^{+3.0}_{-2.9}\times 10^6$|  M⊙. This mass corresponds to a mass-to-light ratio of |$\text{[M/L]}_{\rm r_{h}}=25^{+17}_{-16}$|  M⊙/L⊙, demonstrating that And XXV is most-likely dark matter dominated. We also measure the metallicity of And XXV to be |$\rm [Fe/H]=-1.9\pm 0.1$|  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(150 pc) =  |$2.3^{+1.4}_{-1.1}\times 10^7$|  M⊙ kpc−3, which makes And XXV a clear outlier when compared to other local group 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 521
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 162940604
- Full Text :
- https://doi.org/10.1093/mnras/stad752