2019MNRAS.482.5093P

We present a comprehensive multiwavelength analysis of the merging galaxy cluster MACS J0417.5-1154 at a redshift of z = 0.44, using available images red obtained with Chandra in X-ray, Subaru, Hubble Space Telescope (HST) in optical, Giant Metrewave Radio Telescope (GMRT) in radio, and Bolocam at 2.1 mm wavelength. This is an example of a complex merging galaxy cluster also hosting a steep-spectrum Mpc scale radio halo. The mass distribution obtained by weak-lensing reconstruction shows that MACS J0417.5-1154 belongs to the dissociative class of mergers, where one of its substructures has had its gas content detached after the pericentric passage. We find the main cluster mass M₂₀₀ = 11.5^+3.0_–3.5 ×10¹⁴ M_☉and the smaller second (sub)cluster mass to be M₂₀₀ = 1.96^+1.60_–0.95 ×10¹⁴ M_☉, leading to a large total mass of M₂₀₀ = 13.8^+2.6_–2.8 ×10¹⁴ M_☉. The overall structure, surface brightness profile, temperature, and metal abundance of the intracluster medium all point towards the presence of a cold front and merger induced gas-sloshing motion near the core. We detect a surface brightness edge to the southeast direction at a projected distance of ∼45 arcsec (∼255 kpc) from the centre of this cluster. The X-ray spectral analysis across the inner and outer edges allows us to confirm the detected edge as a cold front. The GMRT 235 MHz observation shows a comet-like extended sychrotron radio halo emission trailing behind the cold front. The peak of the Sunyaev-Zel'dovich decrement is found displaced from the centre of X-ray emission, which is interpreted as consequence of the merger dynamics. The optical HST imaging analysis of the cluster reveals the complex morphology of the brightest cluster galaxy, with three surrounding ring-shaped structures with bright knots, which appear to be images of a multiply imaged strongly lensed background galaxy. In addition, two previously unknown giant arcs are found which are all indications of strong gravitational lensing in this massive system.