Uncovering the nature of dark matter with astronomical observations


Dark matter is a form of matter that makes up 85% of the matter in the Universe, however its nature is one of the great unsolved mysteries of modern physics and cosmology. Recent astronomical observations of merging galaxy clusters are showing an offset between the inferred position of the dark matter halo and the stars. In numerical simulations, if dark matter is non-interacting it remains tightly bound near the stars, but if forces between dark matter particles exist, dark matter temporarily lags behind stars. Observations are then reviving interest in the possibility that dark matter particles interact with each other.
The EAGLE collaboration has recently completed a simulation series that have achieved an unprecedentedly good match to the real Universe. The proposed research is centred in the implementation of self-interacting dark matter (SIDM) in the EAGLE simulations to analyse signatures of SIDM in observations of merging galaxy clusters. The result will be a coherent physical picture of how the collision of galaxies depends on the interacting properties of the dark matter particle, and will ultimately fill a major gap in our understanding of dark matter.
In a groundbreaking work, I have demonstrated through simple analytic modelling that the merger and accretion rates of dark matter halos `slow down' in recent times due to the accelerated expansion of the Universe. By combining this work with cosmological simulations I derived a physically motivated model for the dark matter halo density profile as a function of halo mass and redshift, that has been widely used by X-ray and weak lensing studies. In this VENI fellowship I will extend this research by accounting for the effects of SIDM in the merger history of dark matter halos.


Project number


Main applicant

Dr. C.A. Correa

Affiliated with

Universiteit Leiden, Faculteit der Wiskunde en Natuurwetenschappen, Sterrewacht Leiden


01/10/2019 to 30/09/2022