Comparison of Sunyaev-Zel’dovich measurements fromPlanckand from the Arcminute Microkelvin Imager for 99 galaxy clusters

Abstract

We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel'dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement with higher angular resolution, 3 arcmin compared to the Planck beams of 5-10 arcmin. The AMI observations thus provide validation of the cluster detections, improved positional estimates, and a consistency check on the fitted size (θ s ) and flux (Y tot ) parameters in the generalised Navarro, Frenk and White (GNFW) model. We detect 99 of the clusters. We use the AMI positional estimates to check the positional estimates and error-bars produced by the Planck algorithms PowellSnakes and MMF3. We find that Y tot values as measured by AMI are biased downwards with respect to the Planck constraints, especially for high Planck-S/N clusters. We perform simulations to show that this can be explained by deviation from the universal pressure profile shape used to model the clusters. We show that AMI data can constrain the α and β parameters describing the shape of the profile in the GNFW model for individual clusters provided careful attention is paid to the degeneracies between parameters, but one requires information on a wider range of angular scales than are present in AMI data alone to correctly constrain all parameters simultaneously.

Physical modelling of galaxy clusters detected by thePlancksatellite

“…• Compared to the results of simulations of large clusters carried out in Perrott et al (2015), which test the robustness of the 'universal' pressure profile, the case 4) bias appears relatively small in magnitude, and in the same direction (downward). When comparing the case 4) results with the small cluster simulations of Perrott et al (2015), the latter shows a relatively small bias in the opposite direction.…”

“…The clusters detected by Planck form the basis of the sample considered in this work. Perrott et al (2015) (from here on YP15) present the results of the AMI follow-up of Planck clusters-this follow-up is analysed using the 'observational model' , which parameterises a cluster in terms of its integrated Comptonisation parameter Y and angular scale θ. YP15 find that these AMI estimates for Y are consistently lower than the values obtained from Planck data, and conclude that this may indicate that the cluster pressure profiles are deviating from the 'universal' one. Here, we try to overcome this by considering a model which uses redshift information to break this degeneracy.…”

AMI-LA observations of the SuperCLASS supercluster

“…We also have quasi-simultaneous observations with the AMI Small Array (AMI-SA) in hand. With sensitivity to emission on much larger angular scales, the AMI-SA has proven successful at detecting the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters (for example Perrott et al 2015;AMI Consortium: Shimwell et al 2013). We will use the catalogue produced in this Figure 11.…”

First detection of a virial shock with SZ data: implication for the mass accretion rate of Abell 2319

“…During the last few years, a large number of tSZ experiments, both ground-based (e.g. Hasselfield et al 2013;Adam et al 2014;Perrott et al 2015;Bleem et al 2015;Kitayama et al 2016) and satellite missions (Bennett et al 2013;Planck Collaboration 2015results I 2016, have proved the tSZ effect to be an excellent observable to trace shocks inside galaxy clusters (see e.g. Planck Collaboration int.…”