Non-parametric modeling of the intra-cluster gas using APEX-SZ bolometer imaging data

Abstract

Aims. We aim to demonstrate the usability of mm-wavelength imaging data obtained from the APEX-SZ bolometer array to derive the radial temperature profile of the hot intra-cluster gas out to radius r 500 and beyond. The goal is to study the physical properties of the intra-cluster gas by using a non-parametric de-projection method that is, aside from the assumption of spherical symmetry, free from modeling bias. Methods. We use publicly available X-ray spectroscopic-imaging data in the 0.7−2 keV energy band from the XMM-Newton observatory and our Sunyaev-Zel'dovich Effect (SZE) imaging data from the APEX-SZ experiment at 150 GHz to de-project the density and temperature profiles for a well-studied relaxed cluster, Abell 2204. We derive the gas density, temperature and entropy profiles assuming spherical symmetry, and obtain the total mass profile under the assumption of hydrostatic equilibrium. For comparison with X-ray spectroscopic temperature models, a re-analysis of recent Chandra observation is done with the latest calibration updates. We compare the results with that from an unrelaxed cluster, Abell 2163, to illustrate some differences between relaxed and merging systems. Results. Using the non-parametric modeling, we demonstrate a decrease of gas temperature in the cluster outskirts, and also measure gas entropy profiles, both of which are done for the first time independently of X-ray spectroscopy using the SZE and X-ray imaging data. The gas entropy measurement in the central 100 kpc shows the usability of APEX-SZ data for inferring cluster dynamical states with this method. The contribution of the SZE systematic uncertainties in measuring T e at large radii is shown to be small compared to XMM-Newton and Chandra systematic spectroscopic errors. The total mass profile obtained using the hydrostatic equilibrium assumption is in agreement with the published X-ray and weak lensing results; the upper limit on M 200 derived from the non-parametric method is consistent with the NFW model prediction from weak lensing analysis.

X-ray calibration of Sunyaev-Zel’dovich scaling relations with the ACCEPT catalogue of galaxy clusters observed by Chandra

“…Current angular resolutions of SZ experiments are in fact too low to reach direct observations of y 0 . On the other hand, recent non-parametric deprojections of SZ imaging data have shown a good agreement with the N07 pressure profile (Basu et al 2010). The accuracy of the deprojection and the robustness of the model adopted for P e (r) are therefore more Figure 8.…”

“…In fact, this still rough diagnostic is strongly limited by the errors on Y S , which are here dominated by uncertainties associated with the X-ray observed temperature profiles. The encouraging results of the first deprojections performed on SZ maps (Basu et al 2010) suggest that this correlation could be improved by exploiting SZ-observed radial pressure profiles. Figure 10.…”

Frequency multiplexed superconducting quantum interference device readout of large bolometer arrays for cosmic microwave background measurements

“…[34][35][36][37][38][39][40][41][42][43][44][45][46] and APEX-SZ. [47][48][49] Other implementations of frequency multiplexed TES readout systems are described in Refs. 50 and 51. This paper is outlined as follows.…”

Deeply cooled core of the Phoenix galaxy cluster imaged by ALMA with the Sunyaev–Zel’dovich effect

“…A combination of SZE and X-ray images provides a measure of temperature and density of the ICM independently of the X-ray spectroscopy (e.g., Kitayama et al 2004;Nord et al 2009;Basu et al 2010). Assuming spherical symmetry and h = 0.7 for this particular purpose, we performed non-parametric deprojection of electron density ne and temperature T as described in detail below.…”