Basu, K.K.BasuSommer, M.M.SommerErler, J.J.ErlerEckert, D.D.EckertVAZZA, FRANCOFRANCOVAZZAMagnelli, B.B.MagnelliBertoldi, F.F.BertoldiTOZZI, PaoloPaoloTOZZI2020-05-062020-05-0620160722-6691http://hdl.handle.net/20.500.12386/24547We report on the first ALMA measurement of a galaxy cluster merger shock, observed at the location of a radio relic in the famous El Gordo galaxy cluster at redshift z 0.9. Located at about half the current age of the Universe, this is also the most distant example of a directly measured astrophysical shock. ALMA Band 3 was utilised to measure the Sunyaev-Zel'dovich (SZ) effect signature that confirms a small-scale change in pressure as expected from the passage of a shock in the intracluster medium. The results support a previous radio-based estimate of the shock Mach number and display similarities, and also some mild tensions, with the X-ray based results. Most importantly, these results show the potential of ALMA to detect galaxy cluster shocks, observations that will advance our knowledge of cluster formation, non-thermal particle acceleration and amplification of magnetic fields across the entire observable Universe where such relic shocks can be found.STAMPAenArticlehttp://www.eso.org/sci/publications/messenger/2016Msngr.166...53BFIS/05 - ASTRONOMIA E ASTROFISICAScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation