What boost galaxy mergers in two massive galaxy protoclusters at z = 2.24?
What boost galaxy mergers in two massive galaxy protoclusters at z = 2.24?
复制标题
是什么促进了 z = 2.24 处两个巨大星系原团的星系合并？
DOI：
10.1093/mnras/stad1543
复制
发表时间：
2023
影响因子：
4.8
通讯作者：
Liu, Wenhao
中科院分区：
文献类型：
--
作者：
Liu, Shuang;Zheng, Xian Zhong;Shi, Dong Dong;Cai, Zheng;Fan, Xiaohui;Wang, Xin;Yuan, Qirong;Xu, Haiguang;Pan, Zhizheng;Liu, Wenhao
刻画高红移原星系团中星系的结构特征，是我们理解星系演化和结构形成早期阶段环境效应的关键。在这项研究中，我们利用哈勃太空望远镜的H波段成像数据，分别评估了两个大质量原星系团BOSS1244和BOSS1542最密集区域的85H和87Hα发射线候选者(HEA)的结构性质。我们的结果显示，BOSS1244(BOSS1542)的真配对分数为22%±0.5%，与Gyr−1的合并率为0.41%±0.09(0.52%±0.04)，而Gyr 1与LOG⊙)≥(M*/M⊙)≥10.3)的合并率为0.41%。这一比率是同期普通田块的1.8(2.8)倍。我们的HAES样本显示出半光半径和S指数，它们覆盖的范围比外场恒星形成星系更广。此外，约15%的HAe与最庞大的(对数 (M*/M⊙)≳11)球体占主导地位的种群一样紧凑。这些结果表明，星系的高密度和冷的动力学状态(即S−1的速度弥散)是驱动星系合并和促进两个原星系团结构演化的关键因素。我们的发现还表明，局地环境(在群体尺度上)和全球环境在塑造原星系团的星系形态方面都起着至关重要的作用。这一点从观测到的BOSS1244和BOSS1542星系结构性质的系统差异中可见一斑。
Characterizing the structural properties of galaxies in high-redshift protoclusters is key to our understanding of the environmental effects on galaxy evolution in the early stages of galaxy and structure formation. In this study, we assess the structural properties of 85 and 87 Hα emission-line candidates (HAEs) in the densest regions of two massive protoclusters, BOSS1244 and BOSS1542, respectively, using theHubble Space Telescope(HST)H-band imaging data. Our results show a true pair fraction of 22 ± 5 (33 ± 6) per cent in BOSS1244 (BOSS1542), which yields a merger rate of 0.41 ± 0.09 (0.52 ± 0.04) Gyr−1for massive HAEs with log (M*/M⊙) ≥ 10.3. This rate is 1.8 (2.8) times higher than that of the general fields at the same epoch. Our sample of HAEs exhibits half-light radii and Sérsic indices that cover a broader range than field star-forming galaxies. Additionally, about 15 per cent of the HAEs are as compact as the most massive (log (M*/M⊙) ≳ 11) spheroid-dominated population. These results suggest that the high galaxy density and cold dynamical state (i.e. velocity dispersion of <400 km s−1) are key factors that drive galaxy mergers and promote structural evolution in the two protoclusters. Our findings also indicate that both the local environment (on group scales) and the global environment play essential roles in shaping galaxy morphologies in protoclusters. This is evident in the systematic differences observed in the structural properties of galaxies between BOSS1244 and BOSS1542.