发表机构
University of Utah; The Hong Kong University of Science and Technology（犹他大学; 香港科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究吸热型非弹性暗物质在原初暗星中的俘获，揭示运动学阈值开启与持久非热储库的形成，表明非弹性俘获不补充热湮灭核，为暗星-暗物质协同演化提供新机制。
AI 中文摘要
LUX-ZEPLIN实验最近报告的248-keV核反冲候选事件重新激发了人们对吸热型非弹性暗物质的兴趣，促使我们研究其在原初暗星中的俘获过程。与暗星演化中传统的弹性俘获图像相比，吸热型俘获增加了两个定性特征。首先，它仅在增长中的恒星跨越一个致密性阈值后才开启，该阈值表示为运动学半径$R_{\rm kin}\propto\mu_{\chi}M_\star/\delta$，由恒星质量、暗物质-原子核约化质量以及质量劈裂决定。吸积增长使恒星穿过该阈值，俘获率在阈值之上以二次方形式开启。其次，尽管新俘获的粒子通常起始于非热束缚轨道，吸热运动学可以使这一通常瞬态的粒子群在空间上保持延展，使其成为一个持久存在的储库，而非通往热核的中间步骤。通过追踪完整的态改变碰撞链，我们发现该储库先急剧压缩然后停滞，因为处于低于致密性依赖轨道能的基态粒子在恒星中任何位置都不允许发生上散射。百分之一量级的半径收缩会重新开启弛豫过程。这些运动学结果不依赖于激发态是迅速衰变还是长寿命。因此，非弹性俘获不会补充热湮灭核。被俘获的粒子群形成一个演化的轨道分布，建立起恒星与核心及储库中暗物质之间的协同演化动力学，我们将在姊妹论文中对此进行详细阐述。
英文摘要
The recent 248-keV nuclear recoil candidate reported by LUX-ZEPLIN has renewed interest in endothermic inelastic dark matter, motivating us to examine its capture in primordial dark stars. Relative to the conventional elastic-capture picture in dark star evolution, endothermic capture adds two qualitative features. First, it opens only after the growing star crosses a compactness threshold, expressed as a kinematic radius $R_{\rm kin}\proptoμ_χM_\star/δ$ set by the stellar mass, the dark-matter--nucleus reduced mass and the mass splitting. The accreting growth carries the star through the threshold, and the capture rate turns on quadratically above it. Second, although newly captured particles generically begin on nonthermal bound orbits, endothermic kinematics can keep this normally transient population spatially extended, turning it into a persistent reservoir rather than an intermediate step toward a thermal core. Following complete chains of state-changing collisions, we find that the reservoir compacts sharply and then stalls, because a ground state particle below a compactness-dependent orbital energy has no allowed up-scatter anywhere in the star. A percent-level radius contraction reopens the relaxation. These kinematic results do not depend on whether the excited state decays promptly or is long-lived. As a result, inelastic capture does not replenish a thermal annihilation core. The captured population forms an evolving orbital distribution that sets up the co-evolutionary dynamics between the star and the dark matter in the core and the reservoir, which we develop in a companion paper.
Comments22 pages, 8 figures. Comments are welcome
