AI 中文总结
本研究结合FVSS与文献数据，对天炉座星系团中心星系NGC 1399外区球状星团开展动力学质量建模，证实两类暗物质晕均能匹配观测，且纳入星系团内球状星团对建模结果有重要影响。
AI 中文摘要
NGC 1399 是天炉座星系团的明亮中心星系，拥有延展至200千秒差距之外、进入其外晕的大量球状星团（GCs），延伸范围约为6.5个有效半径（Re）。我们利用球状星团的综合径向速度星表，对NGC 1399直至5个有效半径（约150千秒差距）的范围开展动力学质量建模，该星表结合了天炉座星系团甚大望远镜光谱巡天（FVSS）的数据与文献中的先前测量结果。我们应用球形詹森方程，对NGC 1399的球状星团运动学进行色散-峰度建模，以推导其质量分布和球状星团轨道各向异性。我们还研究了将星系团内球状星团纳入质量建模的影响，这些球状星团基于空间 segregation 和速度σ-剪切法筛选得出。我们的研究结果表明，类尖峰（NFW）和类核心（Burkert）暗物质晕均能重现观测到的球状星团运动学。将星系团内球状星团纳入质量建模，两种晕类型均得出大致一致的质量分布；对于NFW晕，完整球状星团样本给出的维里质量为log M_vir = 13.81 ± 0.09 M☉，略高于Burkert晕的推导值。无论采用何种暗物质晕分布，我们都观测到星系团内球状星团在外部区域呈现径向各向异性，尤其是在蓝色、贫金属的球状星团中。这些结果表明，NGC 1399外晕中的球状星团受到与星系团引力势相关的额外晕成分的影响。这些外晕球状星团中观测到的径向各向异性，为它们从外部源吸积形成提供了有力的动力学证据，与先前球状星团的测光和光谱研究结果一致。本研究强调，将星系团内球状星团纳入动力学质量建模，对于充分考虑暗物质对星系团引力势的贡献具有重要意义。
英文摘要
NGC 1399, the bright central galaxy of the Fornax cluster, hosts an extensive population of globular clusters (GCs) extending beyond 200 kpc into its outer halo, about 6.5 effective radii (Re). We conducted dynamical mass modelling of NGC 1399 out to 5 Re (~150 kpc), using a comprehensive radial velocity catalogue of GCs, combining data from the Fornax cluster VLT spectroscopic survey (FVSS) with prior measurements from the literature. Applying spherical Jeans equations, we performed dispersion-kurtosis modelling of NGC 1399's GC kinematics to derive its mass profile and GC orbital anisotropy. We also investigated the impact of including intra-cluster GCs in the mass modelling, selected based on spatial segregation and a velocity $σ$-clipping method. Our findings indicate that both cusp-like (NFW) and core-like (Burkert) halos can reproduce the observed kinematics of GCs. Including the intra-cluster GCs in the mass modelling yields broadly consistent mass profiles for both halo types, with the full GC sample giving a virial mass of log $\log M_{\rm vir} = 13.81 \pm 0.09~M_{\odot}$ for the NFW halo, slightly higher than the value inferred for the Burkert halo. Regardless of the dark matter halo profile adopted, we observe that the intra-cluster GCs exhibit radial anisotropy in the outskirts, especially among the blue, metal-poor GCs. These results suggest that GCs in NGC 1399's outer halo are influenced by an additional halo component associated with the galaxy cluster potential. The radial anisotropy observed in these outer-halo GCs provides strong dynamical evidence supporting their accretion from external sources, consistent with prior photometric and spectroscopic studies of GCs. This study highlights the importance of including intra-cluster GCs in dynamical mass modelling to fully account for the contribution of dark matter to the cluster gravitational potential.
CommentsAccepted for publication in A&A. 23 pages, 20 figures, including a 7-page appendix with 8 figures
