Title: Multiscale exploration of SMACS J0723.3--7327's intracluster light and past dynamical history Show Chinese title

Title: SMACS J0723.3--7327的星团内光和过去动力学历史的多尺度探索

Abstract: In this work an analysis of the intracluster light (ICL) in the galaxy cluster SMACS J0723.3-7327 (hereafter, SMACS J0723) using JWST/NIRCam deep imaging in six filters (F090W to F444W) is presented. The images were processed for low surface brightness (LSB) science, with additional correction for instrumental scattering in the short-wavelength channels, and analysed using wavelet-based decomposition. The ICL, brightest cluster galaxy (BCG), and satellite galaxies were extracted and modelled, with 2D maps for each component. ICL and ICL+BCG fractions, computed across all filters within a 400 kpc radius, exhibit a flat trend with wavelength, averaging 28% and 34%, respectively. Flux ratios between the BCG and the next brightest members (M$_{12}$, M$_{13}$ and M$_{14}$) also display minimal wavelength dependence. These results indicate that SMACS J0723 is a dynamically evolved cluster with a dominant BCG and well-developed ICL. Five prominent ICL substructures are analysed, contributing to 10-12% of the total ICL+BCG flux budget, slightly exceeding simulation predictions. Their short dynamical timescales suggest an instantaneous ICL injection rate of several $10^3 L_{\odot}\,{\rm yr}^{-1}$, consistent with active dynamical assembly. These findings support a scenario where SMACS J0723's ICL growth is currently driven by galaxy mergers involving the BCG and other bright satellites, rather than by the accretion of pre-processed ICL from a recent cluster merger. However, extrapolating the current injection rate to the cluster's lifetime indicates that additional mechanisms are required to match the growth observed in other clusters over cosmic times. Show Chinese abstract

Abstract: 本文利用 JWST/NIRCam 在六个滤光片（F090W 至 F444W）中的深空成像，对星系团 SMACS J0723.3-7327（以下简称 SMACS J0723）的簇内光（ICL）进行了分析。 这些图像经过处理以用于低表面亮度（LSB）科学研究，并针对短波段通道中的仪器散射进行了额外校正，然后使用基于小波的方法进行分解分析。 提取并建模了 ICL、最亮团星系（BCG）以及卫星星系，并为每个成分生成了二维图。 在 400 kpc 半径范围内，所有滤光片计算得到的 ICL 和 ICL+BCG 分量占比表现出对波长的平坦趋势，分别平均为 28% 和 34%。 BCG 与次亮成员（M$_{12}$、M$_{13}$和 M$_{14}$）之间的流量比也显示出极小的波长依赖性。 这些结果表明，SMACS J0723 是一个动力学演化成熟的星系团，拥有占主导地位的 BCG 和发育良好的 ICL。 分析了五个显著的 ICL 子结构，它们贡献了总 ICL+BCG 流量预算的 10-12%，略微超出模拟预测值。 它们较短的动力学时标表明瞬时 ICL 注入速率为几个$10^3 L_{\odot}\,{\rm yr}^{-1}$，这与活跃的动力学组装一致。 这些发现支持这样一种场景：SMACS J0723 的 ICL 增长目前由涉及 BCG 和其他明亮卫星星系的星系合并驱动，而不是由最近星系团合并中预处理过的 ICL 吸积驱动。 然而，将当前注入速率外推到整个星系团的寿命表明，需要额外的机制来匹配宇宙时间尺度上其他星系团观察到的增长情况。