Title: Stellar CoRGI in MaNGA: Stellar Counter-Rotation Galaxies Identified in MaNGA Survey Show Chinese title

Title: 星系CoRGI在MaNGA中：在MaNGA调查中识别出的恒星反向旋转星系

Abstract: Counter-rotating (CR) galaxies consist of two coplanar stellar disks rotating in opposite directions -- the main, pre-existing disk with an older stellar population and a younger CR disk likely formed from externally acquired gas. Such systems offer a unique opportunity to study disk assembly by analyzing the stellar populations of each component. Using integral field spectroscopic data from the SDSS-IV Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we identified a sample of 120 CR disk galaxies by inspecting their kinematic maps and analyzing the shape of the stellar line-of-sight velocity distribution (LOSVD), which was recovered non-parametrically. For one-third of our sample, we further derived the ages and metallicities of stars for both disks via a spectral decomposition technique. We show that the observed kinematic bimodality -- where the CR disk is either concentrated in the central region (inner~CR) or dominates the outer part of the galaxy (outer~CR) -- is driven by differences in the stellar mass and angular momentum of the CR disk. The wide range of stellar metallicities observed in CR disks suggests that no single source of external material is solely responsible for CR formation in all galaxies; instead, proposed mechanisms such as merger with gas-rich satellites, accretion from cosmic filaments, and exchange of gas between neighboring galaxies can dominate in individual cases. Show Chinese abstract

Abstract: 逆向旋转（CR）星系由两个共面的恒星盘组成，它们以相反方向旋转——主要的、先前存在的盘具有较老的恒星种群，而较年轻的CR盘可能由外部获得的气体形成。 这类系统为通过分析每个组成部分的恒星种群来研究盘状结构的形成提供了独特的机会。 利用SDSS-IV Apache Point Observatory 附近星系测绘调查（MaNGA）的积分场光谱数据，我们通过检查其运动学图并分析恒星视线速度分布（LOSVD）的形状（非参数地恢复）识别出一个包含120个CR盘星系的样本。 对于我们样本的三分之一，我们通过光谱分解技术进一步推导了两个盘中恒星的年龄和金属量。 我们表明，观测到的运动学双峰性——其中CR盘要么集中在中心区域（内CR），要么主导星系的外部分（外CR）——是由CR盘的恒星质量和角动量差异驱动的。 在CR盘中观测到的广泛恒星金属量范围表明，没有单一的外部物质来源单独负责所有星系中的CR形成；相反，提出的机制如与富含气体的卫星星系合并、从宇宙丝状结构吸积以及邻近星系之间的气体交换可能在个别情况下占主导地位。