2016MNRAS.460..569R

Using Arcminute Microkelvin Imager (AMI) Sunyaev-Zel'dovich (SZ) observations towards 10 CLASH (Cluster Lensing and Supernova Survey with Hubble) clusters, we investigate the influence of cluster mergers on observational galaxy cluster studies. Although selected to be largely relaxed, there is disagreement in the literature on the dynamical states of CLASH sample members. We analyse our AMI data in a fully Bayesian way to produce estimated cluster parameters and consider the intrinsic correlations in our Navarro, Frenk and White/generalized Navarro, Frenk and White-based model. Varying pressure profile shape parameters, illustrating an influence of mergers on scaling relations, induces small deviations from the canonical self-similar predictions - in agreement with simulations of Poole et al. (2007) who found that merger activity causes only small scatter perpendicular to the relations. We demonstrate this effect observationally using the different dependences of SZ and X-ray signals to n_e that cause different sensitivities to the shocking and/or fractionation produced by mergers. Plotting Y_X–Mgas relations (where Y_X=MgasT) derived from AMI SZ and from Chandra X-ray gives ratios of AMI and ChandraY_X and M_gas estimates that indicate movement of clusters along the scaling relation, as predicted by Poole et al. (2007). Clusters that have moved most along the relation have the most discrepant T_SZ and T_X estimates: all the other clusters (apart from one) have SZ and X-ray estimates of M_gas, T and Y_X that agree within r_500. We use SZ versus X-ray discrepancies in conjunction with Chandra maps and T_X profiles, making comparisons with simulated cluster merger maps in Poole et al. (2006) to identify disturbed members of our sample and estimate merger stages.