Plan β: core or cusp?

Thomas D. Richardson*, Douglas Spolyar, Matthew D. Lehnert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

The inner profile of dark matter (DM) haloes remains one of the central problems in small-scale cosmology. At present, the problem cannot be resolved in dwarf spheroidal galaxies due to a degeneracy between the DM profile and the velocity anisotropy beta of the stellar population. We discuss a method which can break the degeneracy by exploiting 3D positions and 1D line-of-sight (LOS) velocities. With the full 3D spatial information, we can determine precisely what fraction of each stars LOS motion is in the radial and tangential direction. This enables us to infer the anisotropy parameter beta directly from the data. The method is particularly effective if the galaxy is highly anisotropic. Finally, we argue that such a test could be applied to Sagittarius and potentially other dwarfs with RR Lyrae providing the necessary depth information.

Original languageEnglish
Pages (from-to)1680-1689
Number of pages10
JournalMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume440
Issue number2
DOIs
Publication statusPublished - 11 May 2014

Keywords

  • galaxies: dwarf
  • galaxies: kinematics and dynamics
  • Local Group
  • dark matter
  • DWARF SPHEROIDAL GALAXIES
  • RR LYRAE STARS
  • PERIOD-LUMINOSITY RELATION
  • COLD DARK-MATTER
  • PROPER MOTIONS
  • VELOCITY MOMENTS
  • VARIABLE-STARS
  • DRACO DWARF
  • MILKY-WAY
  • MASS

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