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

质量最大的星系是大规模组装的最终产物。它们是在密集星系团中心发现的具有极端性质的物体，在附近的宇宙中很少见。由于它们记录了过去的相互作用，因此，识别星系形成和演化的各种过程的一个有希望的方法是研究大质量星系的恒星运动学和恒星种群。积分场摄谱仪的最新进展使我们能够以前所未有的细节研究250 Mpc距离内的大质量星系。我们已经开始了对人口最稠密环境中已知的最大星系的调查。被选中的星系是丰富星系团中最亮的星系团星系，也是沙普利超级星系团致密区非中心星系的星等匹配样本。我们样本中的所有星系都大于10^12 Msun。这个项目的目标是把大质量星系的重子性质确定在两个有效半径之内。特别是，我们正在通过瞄准恒星和电离气体来绘制它们的内部运动学，并确定恒星角动量的分布。我们还将确定其恒星的年龄和金属丰度，以及元素丰度。最后，我们将研究暗物质的含量和分布，并寻找这些星系内初始质量函数的可能变化。主要目的是分析我们样本星系的恒星种群，确定它们的星星形成历史，并将它们与恒星的复杂运动学、新的深层成像支持的星系形态及其环境特征联系起来。

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.