📝 SummarXiv

Abstract

We present the results of Chandra and XMM-Newton X-ray imaging and spatially resolved spectroscopy, as well as new MUSTANG2 90 GHz observations of the thermal Sunyaev-Zeldovich effect from MACS J0717.5+3745, an intermediate redshift ($z=0.5458$) and exceptionally massive ($3.5\pm0.6\times10^{15}$ M$_\odot$) Frontier Fields cluster experiencing multiple mergers and hosting an apparent X-ray bright large-scale structure filament. Thermodynamical maps are produced from Chandra, XMM-Newton, and ROSAT data using a new method to model the astrophysical and instrumental backgrounds. The temperature peak of $24\pm4$ keV is also the pressure peak of the cluster and is spatially closely correlated with the Sunyaev-Zeldovich peak from the MUSTANG2 data. We characterize a potential shock candidate at the cluster center, based on the sharp temperature and pressure gradient, and quantify its temperature-derived Mach number in various directions to span a range of $M = (1.7 - 2.0) \pm 0.3$. Bayesian X-ray Analysis methods were used to disentangle different projected spectral signatures for the filament structure, with Akaike and Bayes criteria being used to select the most appropriate model to describe the various temperature components. We report an X-ray filament temperature of $3.1_{-0.3}^{+0.6}$ keV and a density $(3.78\pm0.05)\times10^{-4}\,{\rm cm^{-3}}$, corresponding to an overdensity of $\sim400$ relative to the critical density of the Universe. We estimate the hot gas mass of the filament to be $\sim6.1\times10^{12}~\rm M_\odot$, while its total projected weak lensing measured mass is $\sim(6.8\pm2.7)\times10^{13}~\rm M_\odot$, indicating a hot baryon fraction of 4-10\%.