2012MNRAS.425..162R

We present detailed 16-GHz interferometric observations using the Arcminute Microkelvin Imager (AMI) of 19 clusters with L_X> 7 x 10³⁷W (h₅₀= 1) selected from the Local Cluster Substructure Survey (LoCuSS; 0.142 ≤ z ≤ 0.295) and of Abell 1758b, which is in the field of view of Abell 1758a. We detect and resolve Sunyaev–Zel'dovich (SZ) signals towards 17 clusters, with peak surface brightnesses between 5σ and 23σ. We use a fast, Bayesian cluster analysis to obtain cluster parameter estimates in the presence of radio point sources, receiver noise and primordial cosmic microwave background (CMB) anisotropy. We fit isothermal β-models to our data and assume the clusters are virialized (with all the kinetic energy in gas internal energy). Our gas temperature, T_AMI, is derived from AMI SZ data and not from X-ray spectroscopy. Cluster parameters internal to r₅₀₀ are derived under the assumption of hydrostatic equilibrium. We find the following. (i) Different generalized Navarro–Frenk–White (gNFW) parametrizations yield significantly different parameter degeneracies. (ii) For h₇₀= 1, we find the classical virial radius, r₂₀₀, to be typically 1.6±0.1Mpc and the total mass M_T(r₂₀₀) typically to be 2.0–2.5 x M_T(r₅₀₀). (iii) Where we have found M_T(r₅₀₀) and M_T(r₂₀₀) X-ray and weak-lensing values in the literature, there is good agreement between weak-lensing and AMI estimates (with \mi M\mi T\mo,\mi AMI\mo/\mi M\mi T\mo,\mi WL\mn 1=.\mn 2=–\mn 0.3=+\mn 0.2 and 1.0±0.1 for r₅₀₀ and r₂₀₀, respectively). In comparison, most Suzaku/Chandra estimates are higher than for AMI (with M_T, X_/M_T, AMI_= 1.7±0.2 within r₅₀₀), particularly for the stronger mergers. (iv) Comparison of T_AMI to T_Xsheds light on high X-ray masses: even at large radius, T_X can substantially exceed T_AMI in mergers. The use of these higher T_Xvalues will give higher X-ray masses. We stress that large-radius T_AMIand T_X data are scarce and must be increased. (v) Despite the paucity of data, there is an indication of a relation between merger activity and SZ ellipticity. (vi) At small radius (but away from any cooling flow) the SZ signal (and T_AMI) is less sensitive to intracluster medium disturbance than the X-ray signal (and T_X) and, even at high radius, mergers affect n²-weighted X-ray data more than n-weighted SZ, implying that significant shocking or clumping or both occur in even the outer parts of mergers.

We request that any reference to this paper cites `AMI Consortium: Rodrìguez-Gonzálvez et al. 2012'.