熵稀释机制与暗物质等曲率扰动
Entropy Dilution Mechanism and Dark Matter Isocurvature
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中文总结 AI 辅助
本文研究晚期衰变粒子导致的熵稀释对暗物质等曲率扰动的影响，提出解析求解方法，发现可行场景中暗物质主要来自稀释体衰变，等曲率扰动被抑制，并展示了等曲率扰动与无碰撞阻尼的互补探测能力。
中文摘要 AI 辅助
我们探索了在宇宙学场景中，由晚期衰变的大质量态在太初核合成之前暂时主导宇宙而产生的熵稀释所导致的暗物质等曲率扰动。该稀释机制具有辐射能量密度的非标准标度窗口，这为推导熵稀释因子提供了一种新方法。在超视界尺度上，相同的标度窗口也控制着等曲率扰动的演化，我们提出了一种解析方法来求解扰动方程。我们刻画了暗物质等曲率扰动得以存续并受到宇宙微波背景观测约束的各种情形。对于宇宙学上可行的场景，我们发现暗物质主要来自其稀释体的衰变，并且等曲率扰动被熵稀释因子的$4/3$次幂所抑制。我们的工作展示了等曲率扰动与暗物质无碰撞阻尼作为熵稀释机制有力探针的互补性。
英文摘要
We explore dark matter isocurvature perturbations in cosmological scenarios with entropy dilution resulting from a late decaying massive state that temporarily dominates the universe before big-bang nucleosynthesis. The dilution mechanism features a non-standard scaling window of the radiation energy density, which allows for a new way to derive the entropy dilution factor. On super-horizon scales, the same scaling window also governs the evolution of isocurvature, and we present an analytic approach to solving the perturbation equations. We characterize various regimes where dark matter isocurvature survives and is subject to constraints from the cosmic microwave background observations. For cosmologically viable scenarios, we find that dark matter is dominantly produced from its dilutor decay, and the isocurvature is suppressed by the entropy dilution factor to the $4/3$ power. Our work demonstrates the complementarity between isocurvature and collisionless damping of dark matter as powerful probes of the entropy dilution mechanism.
发表机构
- University of Ljubljana（卢布尔雅那大学）
- Jožef Stefan Institute（约瑟夫斯蒂芬研究所）
- Carleton University（卡尔顿大学）
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