Multi-frequency imaging of the galaxy cluster Abell 2163 using the Sunyaev-Zel'dovich effect

Abstract

Context. Observations of the Sunyaev-Zel'dovich effect (SZE) from galaxy clusters are emerging as a powerful tool in cosmology. Besides large cluster surveys, resolved SZE images of individual clusters can shed light on the physics of the intra-cluster medium (ICM) and allow accurate measurements of the cluster gas and total masses. Aims. We used the APEX-SZ and LABOCA bolometer cameras on the APEX telescope to map both the decrement of the SZE at 150 GHz and the increment at 345 GHz toward the rich and X-ray luminous galaxy cluster Abell 2163 at redshift 0.203. The SZE images were used, in conjunction with archival XMM-Newton X-ray data, to model the radial density and temperature distribution of the ICM, as well as to derive the gas mass fraction in the cluster under the assumption of hydrostatic equilibrium. Methods. We describe the data analysis techniques developed to extract the faint and extended SZE signal. We used the isothermal β model to fit the SZE decrement/increment radial profiles. We performed a simple, non-parametric de-projection of the radial density and temperature profiles, in conjunction with X-ray data, under the simplifying assumption of spherical symmetry. We combined the peak SZE signals derived in this paper with published SZE measurements of this cluster to derive the cluster line-of-sight bulk velocity and the central Comptonization, using priors on the ICM temperature. Results. We find that the best-fit isothermal model to the SZE data is consistent with the ICM properties implied by the X-ray data, particularly inside the central 1 Mpc radius. Inside a radius of ∼1500 kpc from the cluster center, the mean gas temperature derived from our SZE/X-ray joint analysis is 10.4 ± 1.4 keV. The error budget for the derived temperature profile is dominated by statistical errors in the 150 GHz SZE image. From the isothermal analysis combined with previously published data, we find a line-of-sight peculiar velocity consistent with zero; v r = −140 ± 460 km s −1 , and a central Comptonization y 0 = 3.42 ± 0.32 × 10 −4 for Abell 2163. Conclusions. Although the assumptions of hydrostatic equilibrium and spherical symmetry may not be optimal for this complex system, the results obtained under these assumptions are consistent with X-ray and weak-lensing measurements. This shows the applicability of the simple joint SZE and X-ray de-projection technique described in this paper for clusters with a wide range of dynamical states.

A2163: Merger events in the hottest Abell galaxy cluster

“…First detected by Wilbanks et al (1994) and used to determine the Hubble constant in Holzapfel et al (1997), A2163 is the first galaxy cluster detected in the submm band (Lamarre et al 1998). A recent analysis of its SZ signal by Nord et al (2009) has confirmed the exceptionally high temperature of its hot gas content independently of X-ray analyses.…”

Cosmic distance duality relation and the shape of galaxy clusters

“…On the other hand, observations of the Sunyaev-Zeldovich effect (SZE) from galaxy clusters are becoming a powerful tool Article published by EDP Sciences L14, page 1 of 4 in cosmology (Sunyaev & Zeldovich 1972;Cavaliere & FuscoFermiano 1978;De Filippis et al 2005;Cunha et al 2007b;Nord et al 2009;Basu et al 2010). The combination of SZE and X-ray provides the D A (z) of galaxy clusters, hence can be used to constrain some cosmological parameters.…”

The galaxy clusterYSZ−LXandYSZ−Mrelations from the WMAP 5-yr data

“…Dedicated instruments now produce high resolution images of single objects (e.g. Kitayama et al 2004;Halverson et al 2009;Nord et al 2009) and moderately large samples of high-quality SZ measurements of previously-known clusters (e.g., Mroczkowski et al 2009;Plagge et al 2010). In addition, large-scale surveys for clusters using the SZ effect are underway, both from space with the Planck mission (Valenziano et al 2007;Lamarre et al 2003) and from the ground with several dedicated telescopes, such as the South Pole Telescope ) leading to the first discoveries of clusters solely through their SZ signal (Staniszewski et al 2009).…”