星系团环境中矮星系的潮汐磨蚀
Tidal Grinding of Dwarf Galaxies in Cluster Environments
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中文总结 AI 辅助
研究室女座星系团中矮星系投影形状与吸积、转变历史的关系，基于轴比定义子样本，对比其空间和运动学性质，发现扁平与圆形矮星系在分布和速度偏移上有差异，揭示了潮汐作用对矮星系形态的影响，不过圆形子样本投影污染带来一定不确定性。
中文摘要 AI 辅助
矮椭圆星系主导星系团，并为环境驱动的星系演化提供关键约束。本文利用室女座星系团中1108个亮（\(m_g < 19\) 星等）矮星系的均匀样本，研究矮星系的投影形状是否保留了它们吸积和转变历史的信息。基于轴比（\(b/a\)）定义了扁平（\(< 0.70\)）和圆形（\(> 0.74\)）子样本，并比较它们的空间和运动学性质。发现扁平矮星系在星系团中分布更均匀，而圆形矮星系优先占据大质量（\(M_* > 10^{10} M_sun\)）星系周围潮汐场更强的区域。在室女座中心星系（M87）周围中心\(5^\circ x 5^\circ\)区域内，149个矮星系有从公共档案汇编的光谱径向速度。在该区域，两种形状类别也表现出明显的运动学分离：扁平矮星系相对于星系团平均值的视线速度偏移系统性更大（中值\(\Delta v = 654 km/s\)），而圆形矮星系偏移较小（中值\(\Delta v = 414 km/s\)）。扁平矮星系与经历较弱潮汐作用、因此保留更扁平形态的群体一致。相比之下，圆形矮星系与长期潮汐作用（“潮汐磨蚀”）一致，这可能已将最初扁平的系统转变为更圆的球体。然而，圆形子样本的投影污染可能在解释星系固有形状时引入了一些不确定性。
英文摘要
Dwarf elliptical galaxies (dEs) dominate galaxy clusters and provide key constraints on environmentally driven galaxy evolution. Here we examine whether the projected shapes of dEs retain information about their accretion and transformation histories using a homogeneous sample of 1,108 bright (m_g < 19 mag) dEs in the Virgo cluster. Based on the axis-ratio (b/a), we define flat (< 0.70) and round (> 0.74) subsamples and compare their spatial and kinematic properties. We find that flat dEs are distributed more uniformly across the cluster, whereas round dEs preferentially occupy regions of stronger tidal fields around massive (M_* > 10^{10} M_sun) galaxies. Within the central 5^\circ x 5^\circ region around the Virgo central galaxy (M87), 149 dEs have spectroscopic radial velocities compiled from public archives. In this region, the two shape classes also exhibit clear kinematic segregation: flat dEs have systematically larger line-of-sight velocity offsets from the cluster mean (median $Δv = 654 km/s$), whereas round dEs have smaller offsets (median $Δv = 414 km/s$), as expected for a more dynamically relaxed population. Flat dEs are consistent with a population that has experienced weaker tidal processing and consequently retains more flattened morphologies. By contrast, round dEs are consistent with prolonged tidal processing (``tidal grinding'') that may have transformed initially flattened systems into rounder spheroids. However, projection contamination of the round subsample may have introduced some uncertainty in the interpretation of intrinsic galaxy shapes.
