paper

Joining X-ray to lensing: an accurate combined analysis of MACS J0416.12403

arXiv:1705.10322 · doi:10.3847/1538-4357/aa75cc

Abstract

We present a novel approach for a combined analysis of X-ray and gravitational lensing data and apply this technique to the merging galaxy cluster MACS J0416.12403. The method exploits the information on the intracluster gas distribution that comes from a fit of the X-ray surface brightness, and then includes the hot gas as a fixed mass component in the strong lensing analysis. With our new technique, we can separate the collisional from the collision-less diffuse mass components, thus obtaining a more accurate reconstruction of the dark matter distribution in the core of a cluster. We introduce an analytical description of the X-ray emission coming from a set of dual Pseudo-Isothermal Elliptical (dPIE) mass distributions, which can be directly used in most lensing softwares. By combining \emph{Chandra} observations with Hubble Frontier Fields imaging and MUSE spectroscopy in MACS J0416.12403, we measure a projected gas over total mass fraction of approximately at kpc from the cluster center. Compared to the results of a more traditional cluster mass model (diffuse halos plus member galaxies), we find a significant difference in the cumulative projected mass profile of the dark matter component and that the dark matter to total mass fraction is almost constant, out to more than kpc. In the coming era of large surveys, these results show the need of multi-probe analyses for detailed dark matter studies in galaxy clusters.

18 pages, 11 figures, 3 tables; accepted for publication in the Astrophysical Journal

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