PSZ2G091:A massive double cluster at z=0.822 observed by the NIKA2 camera

TL;DR

This paper uses high-resolution NIKA2 observations to analyze the complex morphology of a massive galaxy cluster at z=0.822, highlighting the importance of accounting for bimodality in thermodynamical measurements.

Contribution

It introduces a two-halo model fitting approach to better characterize cluster morphology, improving upon the traditional spherical assumption.

Findings

Detection of bimodal structure in the cluster

Quantification of systematic errors from spherical models

Enhanced pressure profile reconstruction

Abstract

PSZ2 G091.83+26.11 is a massive galaxy cluster with M500 = 7.43 x 10^14 Msun at z = 0.822. This object exhibits a complex morphology with a clear bimodality observed in X-rays. However, it was detected and analysed in the Planck sample as a single, spherical cluster following a universal profile [1]. This model can lead to miscalculations of thermodynamical quantities, like the pressure profile. As future multiwavelength cluster experiments will detect more and more objects at higher redshifts (where we expect the fraction of merging objects to be higher), it is crucial to quantify this systematic effect. In this work, we use high-resolution observations of PSZ2 G091.83+26.11 by the NIKA2 camera to integrate the morphological characteristics of the cluster in our modelling. This is achieved by fitting a two-halo model to the SZ image and then by reconstruction of the resulting projected pressure profile. We then compare these results with the spherical assumption.