CHEX-MATE: Cluster multi-probes in three dimensions (CLUMP-3D)

Under the standard model of hierarchical structure formation, the overall geometry of galaxy clusters is better described by a triaxial ellipse than by a sphere. As a result, the application of spherically symmetric models can result in significant biases, with masses derived from weak-lensing observations being particularly sensitive. These biases can be mitigated by fitting a triaxial model, but this requires deep multi-probe data along with a set of physically motivated models to describe them. We present a multi-probe triaxial analysis method based on the data available for galaxy clusters in the Cluster Heritage project with XMM-Newton – Mass Assembly and Thermodynamics at Endpoint of structure formation (CHEX-MATE), which includes X-ray data from XMM-Newton , Sunyaev-Zel’dovich effect maps from Planck and ACT, and weak-lensing data from Subaru. This work builds upon our previous development of a gas-only X-ray and Sunyaev-Zel’dovich triaxial fitting formalism in Paper I. After verifying our approach using mock observations of model clusters with known properties, we applied it to the CHEX-MATE galaxy cluster PSZ2 G313.33+61.13 (Abell 1689). We found that the cluster is elongated along the line of sight relative to the plane of sky by a factor of ℛ LP = 1.20 ± 0.04. As a result, the weak-lensing mass obtained from our triaxial fit, M 200 c = (13.88 +1.73 −1.43 ) × 10 14 M ⊙ , is significantly lower than the value of (17.77 +2.00 −1.75 ) × 10 14 M ⊙ obtained from a spherically symmetric fit that otherwise employed the same method. Our triaxial fit finds a concentration of c 200 c = 8.66 +2.08 −1.70 , consistent with the spherically symmetric value of 9.99 +2.26 −1.8 , which suggests that the unexpectedly high concentration in Abell 1689 is not due to triaxiality and orientation. We also measured the nonthermal pressure fraction at radii between 0.18–1.37 Mpc and found a minimum of approximately 20% at intermediate radii, increasing to near 30% at the smallest and largest radii, and with a typical measurement precision of ±5%.