We present a consistent analysis of Chandra and XMM-Newton observations of an approximately mass-selected sample of 50 galaxy clusters at 0.15 < z < 0.3 -the "LoCuSS High-L X Sample". We apply the same analysis methods to data from both satellites, including newly developed analytic background models that predict the spatial variation of the Chandra and XMM-Newton backgrounds to < 2% and < 5% precision respectively. To verify the cross-calibration of Chandra-and XMM-Newton-based cluster mass measurements, we derive the mass profiles of the 21 clusters that have been observed with both satellites, extracting surface brightness and temperature profiles from identical regions of the respective datasets. We obtain consistent results for the gas and total hydrostatic cluster masses: the average ratio of Chandra-to XMM-Newton-based measurements of M gas and M X at r 500 are 0.99 ± 0.02 and 1.02 ± 0.05, respectively with an intrinsic scatter of ∼ 3% for gas masses and ∼ 8% for hydrostatic masses. Comparison of our hydrostatic mass measurements at r 500 with the latest LoCuSS weak-lensing results indicate that the data are consistent with non-thermal pressure support at this radius of ∼ 7%. We also investigate the scaling relation between our hydrostatic cluster masses and published integrated Compton parameter Y sph measurements from the Sunyaev-Zel'dovich Array. We measure a scatter in mass at fixed Y sph of ∼ 16% at ∆ = 500, which is consistent with theoretical predictions of ∼ 10 − 15% scatter.

Aims. Imaging and spectroscopy of X-ray extended sources require a proper characterisation of a spatially unresolved background signal. This background includes sky and instrumental components, each of which are characterised by its proper spatial and spectral behaviour. While the X-ray sky background has been extensively studied in previous work, here we analyse and model the instrumental background of the ACIS-I detector on board the Chandra X-ray observatory in very faint mode. Methods. Caused by interaction of highly energetic particles with the detector, the ACIS-I instrumental background is spectrally characterised by the superimposition of several fluorescence emission lines onto a continuum. To isolate its flux from any sky component, we fitted an analytical model of the continuum to observations performed in very faint mode with the detector in the stowed position shielded from the sky, and gathered over the eight-year period starting in 2001. The remaining emission lines were fitted to blank-sky observations of the same period. We found 11 emission lines. Analysing the spatial variation of the amplitude, energy and width of these lines has further allowed us to infer that three lines of these are presumably due to an energy correction artefact produced in the frame store. Results. We provide an analytical model that predicts the instrumental background with a precision of 2% in the continuum and 5% in the lines. We use this model to measure the flux of the unresolved cosmic X-ray background in the Chandra deep field south. We obtain a flux of 10.

The prototype of the NIKA2 camera, NIKA, is a dual-band instrument operating at the IRAM 30-m telescope, which can observe the sky simultaneously at 150 and 260 GHz. One of the main goals of NIKA (and NIKA2) is to measure the pressure distribution in galaxy clusters at high angular resolution using the thermal Sunyaev-Zel'dovich (tSZ) effect. Such observations have already proved to be an excellent probe of cluster pressure distributions even at intermediate and high redshifts. However, an important fraction of clusters host sub-millimeter and/or radio point sources, which can significantly affect the reconstructed signal. Here we report on <20 arcsec angular resolution observations at 150 and 260 GHz of the cluster MACS J1423.8+2404, which hosts both radio and submillimeter point sources. We examine the morphological distribution of the tSZ signal and compare it to other datasets. The NIKA data are combined with Herschel satellite data to study the spectral energy distribution (SED) of the sub-millimeter point source contaminants. We then perform a joint reconstruction of the intracluster medium (ICM) electronic pressure and density by combining NIKA, Planck, XMM-Newton, and Chandra data, focusing on the impact of the radio and sub-millimeter sources on the reconstructed pressure profile. We find that large-scale pressure distribution is unaffected by the point sources because of the resolved nature of the NIKA observations. The reconstructed pressure in the inner region is slightly higher when the contribution of point sources are removed. We show that it is not possible to set strong constraints on the central pressure distribution without accurately removing these contaminants. The comparison with X-ray only data shows good agreement for the pressure, temperature, and entropy profiles, which all indicate that MACS J1423.8+2404 is a dynamically relaxed cool core system. The present observations illustrate the possibility of measuring these quantities with a relatively small integration time, even at high redshift and without X-ray spectroscopy. This work is part of a pilot study aiming at optimizing tSZ observations with the future NIKA2 camera.