标题： ENISALA: 星系团合并和 relaxation 过程中的恒星形成与活动星系核活动 显示英文标题

标题： ENISALA: II. Distinct Star Formation and Active Galactic Nucleus Activity in Merging and Relaxed Galaxy Clusters

摘要： 星系团的增长过程能量巨大，可能会触发或抑制恒星形成和黑洞活动。 ENISALA项目是一系列多波段观测的集合，旨在理解大尺度结构如何驱动星系和黑洞的演化。 在这里，我们介绍了超过800个H$\alpha$发射线星系的光学光谱，这些星系是从14个红移z~0.15-0.31的星系团中选出的，覆盖了各种质量和动力学状态。 我们研究了发射线的性质与宿主星系属性、其在星系团内的位置以及母星系团属性之间的关系。 我们发现了合并星系团和松弛星系团之间显著的区别。 大多数位于合并星系团场内的H$\alpha$发射线星系位于其中心3 Mpc范围内。 在合并星系团内，大部分这些发射线星系是由恒星形成提供动力的，而不受星系团中心距离的影响，而其余部分则由活动星系核提供动力。 在松弛星系团3 Mpc范围内，恒星形成星系很少见，而在其外围（约1.5-3 Mpc）活动星系核最为丰富。 我们发现了一类具有大等效宽度和蓝UV-光学颜色的恒星形成星系，它们仅存在于我们样本中的合并星系团中。 在合并星系团中普遍存在发射线活动，这可能受到最近吸积的富含气体星系中触发活动的支持。 相比之下，我们的松弛星系团观测结果与已建立的模型一致，在这些模型中，黑洞活动在virial半径处增强，而在内落区域恒星形成被抑制。 我们得出结论，发射线星系在合并星系团和松弛星系团中经历了不同的演化路径。 显示英文摘要

摘要： The growth of galaxy clusters is energetic and may trigger and/or quench star formation and black hole activity. The ENISALA project is a collection of multiwavelength observations aimed at understanding how large-scale structure drives galaxy and black hole evolution. Here, we introduce optical spectroscopy of over 800 H$\alpha$ emission-line galaxies, selected in 14 z~0.15-0.31 galaxy clusters, spanning a range of masses and dynamical states. We investigate the nature of the emission lines in relation to the host galaxy properties, its location within the cluster, and the properties of the parent cluster. We uncover remarkable differences between mergers and relaxed clusters. The majority of H$\alpha$ emission-line galaxies in merging cluster fields are located within 3 Mpc of their center. A large fraction of these line-emitters in merging clusters are powered by star formation irrespective of cluster-centric radius, while the rest are powered by active galactic nuclei. Star-forming galaxies are rare within 3 Mpc of relaxed clusters and active galactic nuclei are most abundant at their outskirts (~1.5-3 Mpc). We discover a population of star-forming galaxies with large equivalent widths and blue UV-optical colors, found exclusively in the merging clusters in our sample. The widespread emission-line activity in merging clusters is likely supported by triggered activity in recently-accreted, gas-rich galaxies. By contrast, our observations for relaxed clusters match established models, in which black hole activity is enhanced at the virial radius and star-formation is quenched within the infall region. We conclude that emission-line galaxies experience distinct evolutionary paths in merging and relaxed clusters.