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Constraints on dark matter self-interaction from the internal density profiles of X-COP galaxy clusters

Eckert, D, Ettori, S, Robertson, A, Massey, R, Pointecouteau, E, Harvey, D and Mccarthy, IG (2022) Constraints on dark matter self-interaction from the internal density profiles of X-COP galaxy clusters. Astronomy and Astrophysics, 666. ISSN 0004-6361

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Open Access URL: https://doi.org/10.1051/0004-6361/202243205 (Published version)


The fundamental properties of the postulated dark matter (DM) affect the internal structure of gravitationally bound structures. In the cold dark matter paradigm, DM particles interact only via gravity. Their distribution is well represented by an Einasto profile with shape parameter α-0.18 in the smallest dwarf galaxies or the most massive galaxy clusters alike. Conversely, if DM particles self-interact via additional forces, we expect the mass density profiles of DM halos to flatten in their central regions, thereby increasing the Einasto shape parameter. We measured the structural properties of 12 massive galaxy clusters from observations of their hot gaseous atmosphere, using the X-ray observatory XMM-Newton, and of the Sunyaev-Zel'dovich effect using the Planck all-sky survey. After removing morphologically disturbed systems, we measured Einasto shape parameters with mean (α)=0.19 ± 0.03 and intrinsic scatter σα= 0.06, which is in close agreement with the prediction of the cold dark matter paradigm. We used cosmological hydrodynamical simulations of cluster formation with self-interacting DM (BAHAMAS-SIDM) to determine how the Einasto shape parameter depends on the self-interaction cross section. We used the fitted relation to turn our measurements of α into constraints on the self-interaction cross section, which imply σ/m <-0.19 cm2 g-1 (95% confidence level) at collision velocity vDM-DM∼1000 km s-1. This is lower than the interaction cross section required for DM self-interactions to solve the core-cusp problem in dwarf spheroidal galaxies, unless the cross section is a strong function of velocity.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: EDP Sciences
SWORD Depositor: A Symplectic
Date Deposited: 25 Nov 2022 11:14
Last Modified: 25 Nov 2022 11:15
DOI or ID number: 10.1051/0004-6361/202243205
URI: https://researchonline.ljmu.ac.uk/id/eprint/18217
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