To study systematically the evolution on the angular extents of the galaxy, ICM, and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts $<0.5$, based on all the available data with the Sloan Digital Sky Survey (SDSS) and {\it Chandra}/{\it XMM-Newton}. For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, were derived from a spatially-resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxy number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply towards outside in lower redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies travelling interior of the cluster have continuously fallen towards the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of $10^{44-45}$ erg $\rm s^{-1}$ per cluster from the member galaxies to their environment, which is expected to continue over cosmological time scales.
Investigating the Stellar Mass Growth Histories of Satellite Galaxies as a Function of Infall Time using Phase-Space
我们编译了一个大样本的附近星系的卫星主机使用一个众所周知的SDSS组目录。从这个样本中，我们创建了一个“古代infallers”和“最近infallers”子样本，根据宇宙学模拟预测的星系在相空间中的位置的平均下落时间。我们比较了这两个子样本中星系的恒星质量增长历史，从多波长SED拟合，使用来自宇宙学模拟的恒星形成历史形状的综合库确定。通过同时控制卫星恒星质量和宿主晕质量，我们可以清楚地看到在宿主中度过的时间的影响。正如我们可能预测的那样，古老的infaller人口显示出明显的早期淬火迹象，特别是对于更大质量的宿主中的低质量卫星。更重要的是，我们发现这种影响不仅限于大型主机。我们发现，主机可能被认为是低质量的集团（晕质量$\sim$ 10 $^{13}$ M $_\odot$）可以显着改变他们的卫星，即使是大质量的卫星（恒星质量$\sim$ 10 $^{10}$ M $_\odot$）。有趣的是，我们看到早在8或9 Gyr前，星系团卫星的质量增长历史就发生了变化，当时它们还没有进入当前宿主的维里半径。我们认为，这可能是由于星系被预处理在低质量的子结构在原星系团的郊区，之前的下跌。
Damping of dynamical friction force in self-interacting ultralight dark matter and Fornax timing problem
Faculty of Physics, Taras Shevchenko National University of Kyiv（基辅塔拉斯舍甫琴科国立大学物理学院）；Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院博戈留博夫理论物理研究所）；Institut für Mathematische Physik, Technische Universität Braunschweig（布伦瑞克工业大学数学物理研究所）；Fundamentale Physik für Metrologie FPM, Physikalisch-Technische Bundesanstalt PTB（德国联邦物理技术研究院基础计量物理学部）
The Optical Properties of Host Galaxies of Radio Sources in the Coma Cluster
Beijing Normal University（北京师范大学）；Leiden University（莱顿大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Green Bank Observatory（绿岸天文台）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
Hector Galaxy Survey: Falling in Between - Infalling Galaxies in the Midst of the Abell 3667 Merger
Macquarie University（麦考瑞大学）；Korea Astronomy and Space Science Institute (KASI)（韩国天文学与空间科学研究所）；Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney（悉尼大学物理学院天文研究所）；University of Queensland（昆士兰大学）；University of New South Wales（新南威尔士大学）；Australian National University（澳大利亚国立大学）；Yonsei University（延世大学）；Swinburne University of Technology（斯威本科技大学）
