发表机构
Institute of Corpuscular Physics (IFIC), CSIC–Universitat de València; VALER; Institute for Astronomy, University of Edinburgh; Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche; Osservatorio Astrofisico di Arcetri, Istituto Nazionale di Astrofisica; Istituto nazionale di Fisica Nucleare; McWilliams centre for Cosmology and Astrophysics, Department of Physics, Carnegie Mellon University（核物理研究所（IFIC），西班牙科学研究中心-瓦伦西亚大学; VALER; 爱丁堡大学天文研究所; 复杂系统研究所，意大利国家研究委员会; 阿切特里天体物理观测台，意大利国家天体物理研究所; 意大利国家核物理研究所; 卡内基梅隆大学物理学院麦克威廉斯宇宙学与天体物理学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过解析与数值实验，发现冷暗物质晕中星团轨道演化存在临界质量，由次晕质量函数高端控制，随机加热可延迟球状星团下沉，缓解Fornax时间问题。
AI 中文摘要
嵌入暗物质晕中的大质量恒星系统的轨道演化受竞争过程支配。动力学摩擦移除轨道能量，而暗物质次晕产生的引力场波动则通过随机加热注入能量。我们利用解析论证和数值实验研究了这两种机制之间的平衡。我们表明，对于给定的宿主晕和次晕种群，存在一个临界质量 $M_{\rm crit}$，在该质量下加热与摩擦达到平衡。质量 $M_{\rm cl}>M_{\rm crit}$ 的星团失去轨道能量并沉向晕中心，而质量 $M_{\rm cl}<M_{\rm crit}$ 的星团则获得能量并向外扩张。在 $M_{\rm cl}\simeq M_{\rm crit}$ 时，两种过程平衡，导致星团种群在宿主晕内平均既不沉没也不扩张。在CDM晕中，临界质量主要由次晕质量函数的高端控制。由于大质量次晕本质上稀少，加热与摩擦之间的平衡显示出显著的晕与晕之间的散布。对于与矮椭球星系（dSphs）相关的质量范围内的暗物质晕，我们发现 $M_{\rm crit}\gtrsim 10^5M_\odot$，与Fornax矮椭球星系中球状星团的质量相当。因此，暗物质亚结构的随机加热可能显著延迟球状星团的轨道衰减，并有助于缓解Fornax时间问题。
英文摘要
The orbital evolution of massive stellar systems embedded in dark matter haloes is governed by competing processes. Dynamical friction removes orbital energy, whereas fluctuations in the gravitational field generated by dark matter subhaloes inject energy through stochastic heating. We investigate the balance between these two mechanisms using analytical arguments and numerical experiments. We show that, for a given host halo and subhalo population, there exists a critical mass $M_{\rm crit}$ at which heating and friction balance. Clusters with masses $M_{\rm cl}>M_{\rm crit}$ lose orbital energy and sink towards the centre of the halo, whereas those with $M_{\rm cl}<M_{\rm crit}$ gain energy and expand outwards. At $M_{\rm cl}\simeq M_{\rm crit}$, the two processes balance, leading to a cluster population that, on average, neither sinks nor expands within the host halo. In CDM haloes, the critical mass is primarily controlled by the upper end of the subhalo mass function. Since massive subhaloes are intrinsically rare, the balance between heating and friction shows substantial halo-to-halo scatter. For dark matter haloes in the mass range associated with dwarf spheroidal galaxies (dSphs), we find $M_{\rm crit}\gtrsim 10^5M_\odot$, comparable to the masses of globular clusters in the Fornax dSph. Stochastic heating by dark substructure may therefore significantly delay the orbital decay of globular clusters and help alleviate the Fornax timing problem.
CommentsSubmitted to MNRAS Letters. Comments welcome
