Work

CHEX-MATE: Multiprobe analysis of Abell 1689

Year: 2025

Type: article

Abstract: The nature of the elusive dark matter can be probed by comparing the predictions of the cold dark matter framework with the gravitational field of massive galaxy clusters. However, a robust test of dark matter can only be achieved if the systematic uncertainties in the reconstruction of the gravitational potential are minimized. Techniques based on the properties of intracluster gas rely on the assumption that the gas is in hydrostatic equilibrium within the potential well, whereas gravitational lensing is sensitive to projection effects. Here we attempt to minimize systematics in galaxy cluster mass reconstructions by jointly exploiting the weak gravitational lensing signal and the properties of the hot intracluster gas determined from X-ray and millimeter (Sunyaev-Zel’dovich) observations. We constructed a model to fit the multiprobe information within a common framework, accounting for non-thermal pressure support and elongation of the dark matter halo along the line of sight. We then applied our framework to the massive cluster Abell 1689, which features unparalleled multiwavelength data. In accordance with previous works, we find that the cluster is significantly elongated along the line of sight. Accounting for line-of-sight projections, we require a non-thermal pressure support of 30 − 40% at r500 to match the gas and weak lensing observables. The joint model retrieves a concentration c200 ∼ 7, which is lower and better agrees with the concentration-mass relation than the high concentration retrieved from weak lensing data alone under the assumption of spherical symmetry (c200 ∼ 15). Applying our method to a larger sample will allow us to study the shape of dark matter mass profiles and the level of non-thermal pressure support in galaxy clusters at the same time.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202554743