标题： z=2.51处处于星暴状态的星系团中星系结构演化的加速演变 显示英文标题

标题： Accelerated structural evolution of galaxies in a starbursting cluster at z=2.51

摘要： 在星团星系形成高峰期的结构特性， $z \sim 2-4$提供了关于环境是否以及如何影响星系形成和演化的关键信息。 基于对 z=2.51 星团 J1001 的深 HST/WFC3 成像研究，我们探讨了环境对星团恒星形成星系（SFGs）的结构、颜色梯度和恒星群体的影响。 我们发现，星团 SFGs 平均而言比它们的场星系更小。 这种差异在高质量端 ($M_{\star} > 10^{10.5} M_{\odot}$) 最为明显，几乎所有这些星系都位于场星系的质量-大小关系之下。 高质量的星团 SFGs 也普遍较老且具有陡峭的负颜色梯度，表明可能与强烈的耗散性坍缩有关的早期形成时间。 对于低质量的星团 SFGs，我们揭示了一类具有陡峭正颜色梯度的紧凑星系，而这类星系在场星系中未被观测到。 这表明低质量的紧凑星团 SFGs 可能已经在这一年轻的星团中经历了强烈的环境效应，例如潮汐/湍流压力剥离。 这些结果提供了证据，表明在最早形成的星团中，不同质量的星系的形成过程中，环境效应发挥了不同的作用。 显示英文摘要

摘要： Structural properties of cluster galaxies during their peak formation epoch, $z \sim 2-4$ provide key information on whether and how environment affects galaxy formation and evolution. Based on deep HST/WFC3 imaging towards the z=2.51 cluster, J1001, we explore environmental effects on the structure, color gradients, and stellar populations of a statistical sample of cluster SFGs. We find that the cluster SFGs are on average smaller than their field counterparts. This difference is most pronounced at the high-mass end ($M_{\star} > 10^{10.5} M_{\odot}$) with nearly all of them lying below the mass-size relation of field galaxies. The high-mass cluster SFGs are also generally old with a steep negative color gradient, indicating an early formation time likely associated with strong dissipative collapse. For low-mass cluster SFGs, we unveil a population of compact galaxies with steep positive color gradients that are not seen in the field. This suggests that the low-mass compact cluster SFGs may have already experienced strong environmental effects, e.g., tidal/ram pressure stripping, in this young cluster. These results provide evidence on the environmental effects at work in the earliest formed clusters with different roles in the formation of low and high-mass galaxies.