Inferred Evidence for Dark Matter Kinematic Substructure with SDSS-Gaia

Lina Necib, Mariangela Lisanti, Vasily Belokurov

Research output: Contribution to journalArticle

Abstract

We use the distribution of accreted stars in Sloan Digital Sky Survey-Gaia DR2 to demonstrate that a nontrivial fraction of the dark matter halo within galactocentric radii of 7.5-10 kpc and is in substructure and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.

Original languageEnglish (US)
Article number3
JournalAstrophysical Journal
Volume874
Issue number1
DOIs
StatePublished - Mar 20 2019

Fingerprint

substructures
halos
dark matter
kinematics
debris
debris flow
merger
mounting
orbits
stars
radii
simulation
experiment
distribution

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxy: evolution
  • Galaxy: kinematics and dynamics
  • dark matter
  • stars: kinematics and dynamics
  • surveys

Cite this

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title = "Inferred Evidence for Dark Matter Kinematic Substructure with SDSS-Gaia",
abstract = "We use the distribution of accreted stars in Sloan Digital Sky Survey-Gaia DR2 to demonstrate that a nontrivial fraction of the dark matter halo within galactocentric radii of 7.5-10 kpc and is in substructure and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.",
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Inferred Evidence for Dark Matter Kinematic Substructure with SDSS-Gaia. / Necib, Lina; Lisanti, Mariangela; Belokurov, Vasily.

In: Astrophysical Journal, Vol. 874, No. 1, 3, 20.03.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Inferred Evidence for Dark Matter Kinematic Substructure with SDSS-Gaia

AU - Necib, Lina

AU - Lisanti, Mariangela

AU - Belokurov, Vasily

PY - 2019/3/20

Y1 - 2019/3/20

N2 - We use the distribution of accreted stars in Sloan Digital Sky Survey-Gaia DR2 to demonstrate that a nontrivial fraction of the dark matter halo within galactocentric radii of 7.5-10 kpc and is in substructure and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.

AB - We use the distribution of accreted stars in Sloan Digital Sky Survey-Gaia DR2 to demonstrate that a nontrivial fraction of the dark matter halo within galactocentric radii of 7.5-10 kpc and is in substructure and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.

KW - Galaxy: evolution

KW - Galaxy: kinematics and dynamics

KW - dark matter

KW - stars: kinematics and dynamics

KW - surveys

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