%0 Journal Article %T An extreme case of galaxy and cluster co-evolution at z = 0.7 %+ Centre de Recherche Astrophysique de Lyon (CRAL) %A Ebeling, H. %A Richard, J. %A Smail, I. %A Edge, A. C. %A Koekemoer, A. M. %A Zalesky, L. %< avec comité de lecture %@ 0035-8711 %J Monthly Notices of the Royal Astronomical Society %I Oxford University Press (OUP): Policy P - Oxford Open Option A %V 508 %P 3663-3671 %8 2021 %D 2021 %Z 2109.08798 %Z 2021MNRAS.508.3663E %R 10.1093/mnras/stab2725 %K gravitational lensing: strong %K galaxies: clusters: general %K galaxies: clusters: intracluster medium %K galaxies: elliptical and lenticular %K cD %K galaxies: evolution %K galaxies: kinematics and dynamics %K Astrophysics - Astrophysics of Galaxies %Z Sciences of the Universe [physics]Journal articles %X We report the discovery of eMACS J0252.4-2100 (eMACS J0252), a massive and highly evolved galaxy cluster at z = 0.703. Our analysis of Hubble Space Telescope imaging and VLT/MUSE and Keck/DEIMOS spectroscopy of the system finds a high-velocity dispersion of 1020$^{+180}_{-190}$ km s-1 and a high (if tentative) X-ray luminosity of (1.2 ± 0.4) × 1045 erg s-1 (0.1-2.4 keV). As extreme is the system's brightest cluster galaxy, a giant cD galaxy that forms stars at a rate of between 85 and 300 M yr-1 and features an extended halo of diffuse [O II] emission, as well as evidence of dust. Its most remarkable properties, however, are an exceptionally high ellipticity and a radially symmetric flow of gas in the surrounding intracluster medium, potential direct kinematic evidence of a cooling flow. A strong-lensing analysis, anchored by two multiple-image systems with spectroscopic redshifts, finds the best lens model to consist of a single cluster-scale halo with a total mass of (1.9 ± 0.1) × 1014 M within 250 kpc of the cluster core and, again, an extraordinarily high ellipticity of e = 0.8. Although further, in-depth studies across the electromagnetic spectrum (especially in the X-ray regime) are needed to conclusively determine the dynamical state of the system, the properties established so far suggest that eMACS J0252 must have already been highly evolved well before z ~ 1, making it a prime target to constrain the physical mechanisms and history of the co-evolution or dark-matter haloes and baryons in the era of cluster formation. %G English %2 https://insu.hal.science/insu-03711483/document %2 https://insu.hal.science/insu-03711483/file/stab2725.pdf %L insu-03711483 %U https://insu.hal.science/insu-03711483 %~ ENS-LYON %~ INSU %~ CNRS %~ UNIV-LYON1 %~ CRAL %~ UDL %~ UNIV-LYON