Exploiting high-resolution NIKA2 data to study the intracluster medium and dynamical state of ACT-CL J0240.0+0116

Le résumé fourni par la source

It is crucial to have a detailed understanding of the intracluster medium (ICM) to infer precise cluster physics, such as the cluster’s dynamical state, in order to carry out cluster-based cosmological studies. This knowledge limits the accuracy and precision of mass estimation, which is a key parameter for such studies. In this paper, we conduct an in-depth analysis of cluster ACT-CL J0240.0+0116 using a multi-wavelength approach, with a primary focus on high angular resolution Sunyaev-Zeldovich (SZ) thermal component observations obtained under the New IRAM KIDs Array 2 (NIKA2) Sunyaev-Zeldovich Large Programme (LPSZ). We created composite images using NIKA2, X-ray, and optical galaxy number density maps. The results reveal distinct signs of disturbance within the cluster, with distributions of gas and member galaxies that do not overlap. We also found suggestions for an inflow of matter onto the cluster from the south-west direction. We classified the cluster as disturbed, using morphological indicators derived from its SZ, X-ray, and optical image. The SZ signal in the cluster is also contaminated by a strong central point source. We adopted different approaches to handling this contaminant and found that the estimates of our pressure and hydrostatic mass profiles are robust to the point source mitigation model. The hydrostatic mass of the cluster is estimated at 4.25−0.45+0.50 × 1014 M⊙ in the case where the point source was masked. These values are consistent with the mass estimated using only X-ray data and with the values from previous SZ studies of the Atacama Cosmology Telescope (ACT) survey, with improved precision on the mass estimate. Our findings strongly suggest that ACT-CL J0240.0+0116 is a disturbed cluster system, and the detailed observations and derived values serve as a compelling case study for the capabilities of the LPSZ in mapping the cluster ICM with high precision.

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