Inferring the dark matter velocity anisotropy to the cluster edge
- Svensmark, Jacob ORCID DARK, Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 4. sal, 2100 Copenhagen Ø, Denmark
- Hansen, Steen H DARK, Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 4. sal, 2100 Copenhagen Ø, Denmark
- Martizzi, Davide ORCID DARK, Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 4. sal, 2100 Copenhagen Ø, Denmark
- Moore, Ben Institute for Computational Science, University of Zurich, CH-8057 Zurich, Switzerland
- Tessier, Romaine Institute for Computational Science, University of Zurich, CH-8057 Zurich, Switzerland
- 2020-10-23
Published in:
- Monthly Notices of the Royal Astronomical Society. - Oxford University Press (OUP). - 2020
English
Abstract
Dark matter dominates the properties of large cosmological structures such as galaxy clusters, and the mass profiles of the dark matter have been inferred for these equilibrated structures for years by using cluster X-ray surface brightnesses and temperatures. A new method has been proposed, which should allow us to infer a dynamical property of the dark matter, namely the velocity anisotropy. For the gas a similar velocity anisotropy is zero due to frequent collisions, however, the collisionless nature of dark matter allows it to be non-trivial. Numerical simulations have for years found non-zero and radially varying dark matter velocity anisotropies. Here we employ the method proposed by Hansen & Pifaretti (2007), and developed by Høst et al. (2009) to infer the dark matter velocity anisotropy in the bright galaxy cluster Perseus, to near 5 times the radii previously obtained. We find the dark matter velocity anisotropy to be consistent with the results of numerical simulations, however, still with large error-bars. At half the virial radius we find the dark matter velocity anisotropy to be non-zero at 1.7 σ, lending support to the collisionless nature of dark matter.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1093/mnras/staa3279
- ISSN 0035-8711
- Persistent URL
- https://sonar.ch/global/documents/236007
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