Detailed Sunyaev-Zel'dovich study with AMI of 19 LoCuSS galaxy clusters: masses and temperatures out to the virial radius

We present detailed 16-GHz interferometric observations using the Arcminute Microkelvin Imager (AMI) of 19 clusters with L X > 7 10 37 W (h 50 = 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 5 and 23 . 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 -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 r 500 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 h 70 = 1, we find the classical virial radius, r 200 , to be typically 1.6 0.1 Mpc and the total mass M T (r 200 ) typically to be 2.0-2.5 M T (r 500 ). (iii) Where we have found M T (r 500 ) and M T (r 200 ) X-ray and weak-lensing values in the literature, there is good agreement between weak-lensing and AMI estimates (with M T,AMI /M T,WL = 1.2 +0.2 -0.3 and 1.0 0.1 for r 500 and r 200 , respectively). In comparison, most Suzaku/Chandra estimates are higher than for AMI (with M T,X /M T,AMI = 1.7 0.2 within r 500 ), particularly for the stronger mergers. (iv) Comparison of T AMI to T X sheds 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 X values will give higher X-ray masses. We stress that large-radius T AMI and 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 n 2 -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.