由非弹性散射导致的与质量相关的暗物质缺失
Mass-Dependent Dark Matter Deficit from Inelastic Scattering
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中文总结 AI 辅助
该研究提出放热非弹性暗物质模型，通过速度依赖散射解释星系中心暗物质缺失随恒星质量的增长，并匹配四个质量区间的观测数据。
中文摘要 AI 辅助
最近的恒星运动学和中性氢观测表明，邻近星系中心数十千秒差距内的暗物质存在缺失，且相对于流体动力学模拟，这种缺失随恒星质量系统地增长。我们证明，这种质量依赖性可以源于具有强速度依赖性散射的放热非弹性暗物质。两个近乎简并的暗物质态通过矢量和标量媒介子相互作用，这些媒介子具有相反符号的贡献和不相等的力程。由此产生的耦合道动力学在低速下抑制了s波转换，同时在数百公里/秒的速度下保留了p波增强，此时向下散射注入动能并降低中心暗物质密度。在矮星系速度下，转换仍被抑制，而弹性散射仍可驱动核心形成，与观测到的矮星系聚集模式一致。晚期暗部门相变以及低速抑制，使得激发态比例在晕形成前保持较大。使用覆盖四个观测恒星质量区间的代表性暗物质晕，我们发现该模型能够解释所有四个区间中推断出的暗物质缺失，包括其随恒星质量的系统性增长，而其影响在星系团速度下减弱。因此，与流体动力学模拟日益增长的差异可能为先前隐藏的暗物质微观物理学提供一瞥。
英文摘要
Recent stellar-kinematic and neutral-hydrogen observations indicate a dark matter deficit within the central tens of kiloparsecs of nearby galaxies that grows systematically with stellar mass relative to hydrodynamical simulations. We show that this mass dependence can arise from exothermic inelastic dark matter with strongly velocity-dependent scattering. Two nearly degenerate dark matter states interact through vector and scalar mediators with opposite-sign contributions and unequal ranges. The resulting coupled-channel dynamics suppresses $s$-wave conversion at low velocity while retaining a $p$-wave enhancement at several hundred $\rm km/s$, where down-scattering injects kinetic energy and lowers central dark matter densities. At dwarf velocities, conversion remains suppressed while elastic scattering can still drive core formation consistent with the observed dwarf-clustering pattern. A late dark-sector phase transition, along with the low-velocity suppression, preserves a large excited-state fraction until halo formation. Using representative halos spanning the four observed stellar-mass bins, we find that the model accounts for the inferred dark matter deficit in all four bins, including its systematic growth with stellar mass, while its impact weakens toward cluster velocities. The growing discrepancy with hydrodynamical simulations may therefore offer a glimpse of previously hidden dark matter microphysics.
发表机构
- Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）
- School of Astronomy and Space Sciences, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）
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