Skip to main content

Research Repository

Advanced Search

Hydrodynamical simulations of merging galaxy clusters: giant dark matter particle colliders, powered by gravity

Sirks, Ellen L; Harvey, David; Massey, Richard; Oman, Kyle A; Robertson, Andrew; Frenk, Carlos; Everett, Spencer; Gill, Ajay S; Lagattuta, David; McCleary, Jacqueline

Hydrodynamical simulations of merging galaxy clusters: giant dark matter particle colliders, powered by gravity Thumbnail


David Harvey

Profile Image

Dr Kyle Oman
Associate Professor - Royal Society Dorothy Hodgkin Fellow

Andrew Robertson

Spencer Everett

Ajay S Gill

Jacqueline McCleary


Terrestrial particle accelerators collide charged particles, then watch the trajectory of outgoing debris – but they cannot manipulate dark matter. Fortunately, dark matter is the main component of galaxy clusters, which are continuously pulled together by gravity. We show that galaxy cluster mergers can be exploited as enormous, natural dark matter colliders. We analyse hydrodynamical simulations of a universe containing self-interacting dark matter (SIDM) in which all particles interact via gravity, and dark matter particles can also scatter off each other via a massive mediator. During cluster collisions, SIDM spreads out and lags behind cluster member galaxies. Individual systems can have quirky dynamics that makes them difficult to interpret. Statistically, however, we find that the mean or median of dark matter’s spatial offset in many collisions can be robustly modelled, and is independent of our viewing angle and halo mass even in collisions between unequal-mass systems. If the SIDM cross-section were σ/m = 0.1 cm2 g−1 = 0.18 barn GeV−1, the ‘bulleticity’ lag would be ∼5 per cent that of gas due to ram pressure, and could be detected at 95 per cent confidence level in weak lensing observations of ∼100 well-chosen clusters.

Journal Article Type Article
Acceptance Date Apr 10, 2024
Online Publication Date Apr 17, 2024
Publication Date 2024-05
Deposit Date Jul 4, 2024
Publicly Available Date Jul 4, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 530
Issue 3
Pages 3160-3170
Public URL


You might also like

Downloadable Citations