A joint ALMA–Bolocam–Planck SZ study of the pressure distribution in RX J1347.5−1145

Abstract

ABSTRACT We report the joint analysis of single-dish and interferometric observations of the Sunyaev–Zeldovich (SZ) effect from the galaxy cluster RX J1347.5−1145. We have developed a parametric fitting procedure that uses native imaging and visibility data, and tested it using the rich data sets from ALMA, Bolocam, and Planck available for this object. RX J1347.5−1145 is a very hot and luminous cluster showing signatures of a merger. Previous X-ray-motivated SZ studies have highlighted the presence of an excess SZ signal south-east of the X-ray peak, which was generally interpreted as a strong shock-induced pressure perturbation. Our model, when centred at the X-ray peak, confirms this. However, the presence of two almost equally bright giant elliptical galaxies separated by ∼100 kpc makes the choice of the cluster centre ambiguous, and allows for considerable freedom in modelling the structure of the galaxy cluster. For instance, we have shown that the SZ signal can be well described by a single smooth ellipsoidal generalized Navarro–Frenk–White profile, where the best-fitting centroid is located between the two brightest cluster galaxies. This leads to a considerably weaker excess SZ signal from the south-eastern substructure. Further, the most prominent features seen in the X-ray can be explained as predominantly isobaric structures, alleviating the need for highly supersonic velocities, although overpressurized regions associated with the moving subhaloes are still present in our model.