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Article Dans Une Revue Astron.Astrophys. Année : 2024

Investigating the Dark Matter Halo of NGC 5128 using a Discrete Dynamical Model

Antoine Dumont
  • Fonction : Auteur
Anil C Seth
  • Fonction : Auteur
Jay Strader
  • Fonction : Auteur
David J Sand
  • Fonction : Auteur
Allison K Hughes
  • Fonction : Auteur
Denija Crnojević
  • Fonction : Auteur
Duncan A Forbes
  • Fonction : Auteur
Mario Mateo
  • Fonction : Auteur
Sarah Pearson
  • Fonction : Auteur

Résumé

As the nearest accessible massive early-type galaxy, NGC 5128 presents an exceptional opportunity to measure dark matter halo parameters for a representative elliptical galaxy. Here we take advantage of rich new observational datasets of large-radius tracers to perform dynamical modeling of NGC 5128, using a discrete axisymmetric anisotropic Jeans approach with a total tracer population of nearly 1800 planetary nebulae, globular clusters, and dwarf satellite galaxies extending to a projected distance of 250 kpc from the galaxy center. We find that a standard NFW halo provides an excellent fit to nearly all the data, excepting a subset of the planetary nebulae that appear to be out of virial equilibrium. The best-fit dark matter halo has a virial mass of Mvir=4.4+2.41.4×1012M, and NGC 5128 appears to sit below the mean stellar mass--halo mass and globular cluster mass--halo mass relations, which both predict a halo virial mass closer to Mvir1013M. The inferred NFW virial concentration is cvir=5.6+2.41.6, nominally lower than cvir9 predicted from published cvir--Mvir relations, but within the 30% scatter found in simulations. The best-fit dark matter halo constitutes only 10% of the total mass at 1 effective radius but 50% at 5 effective radii. The derived halo parameters are relatively insensitive to reasonable variations in the tracer population considered, tracer anisotropies, and system inclination. Our analysis highlights the value of comprehensive dynamical modeling of nearby galaxies, and the importance of using multiple tracers to allow cross-checks for model robustness.
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hal-04154305 , version 1 (17-01-2025)

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Antoine Dumont, Anil C Seth, Jay Strader, David J Sand, Karina Voggel, et al.. Investigating the Dark Matter Halo of NGC 5128 using a Discrete Dynamical Model. Astron.Astrophys., 2024, 685, pp.A132. ⟨10.1051/0004-6361/202347243⟩. ⟨hal-04154305⟩
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