Pinning down the assembly of most massive galaxies with the M3G Survey

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The most massive galaxies are the end products of mass assembly. They are objects of extreme properties found in the centres of the densest galaxy clusters and are rare in the nearby Universe. Because they keep records of past interactions, a promising way of identifying various processes of galaxy formation and evolution is, therefore, to study the stellar kinematics and stellar populations of massive galaxies. The latest advances in the construction of integral-field spectrographs allow us to investigate massive galaxies within a distance of 250 Mpc with unprecedented details. We have initiated a survey of the most massive galaxies known in the most densely populated environments. The selected galaxies are the brightest cluster galaxies in rich galaxy clusters and a magnitude-matching sample of non-central galaxies in the densest region of the Shapley Super Cluster. All galaxies in our sample are more massive than 10^12 Msun. The goal of this project is to pin down the baryonic properties of massive galaxies out to two effective radii. In particular, we are mapping their internal kinematics by targeting stars and ionised gas, and determining the distribution of the stellar angular momentum. We will also ascertain the ages and metallicities of their stars, as well as the element abundances. Finally, we will investigate the content and distribution of dark matter, and look for a possible variation of the initial mass function within these galaxies. The main objective is to analyse the stellar populations of our sample galaxies, determine their star formation histories and link them with the complex kinematics of the stars, the morphology of galaxies supported by new deep imaging, and their environmental characteristics.