AI 中文总结
该研究提出自冷却暗区机制，可大幅缓解轻热暗物质受莱曼α的约束，使满足观测能量密度的冻结暗物质质量低至约1.9（0.7）keV，二次冷却或主导约束修改。
AI 中文摘要
轻的热产生暗物质会受到强约束，该约束源于其自由流动对结构形成的抑制作用。本文表明，若暗区经历自冷却，这些限制会显著缓解；自冷却是暗区等离子体在冻结产生阶段通过同类相食自相互作用降低温度的新机制。我们发现，在亚MeV区域，莱曼α（Lyman-α）约束可被修改几个数量级，且满足观测到的能量密度的冻结暗物质质量可低至≈1.9（0.7）keV，而模拟得出的温暗物质约束为≈5.7（1.9）keV。值得注意的是，由同时高效的逆同类相食过程和衰变过程引发的二次冷却，而非同类相食反应本身的自热化，可主导对莱曼α约束的修改。
英文摘要
Light thermally produced dark matter is subject to strong bounds stemming from its free-streaming impact on suppressing structure formation. In this paper we show that these limits are significantly alleviated if the dark sector undergoes self-cooling, a new mechanism for lowering the temperature of the dark sector plasma through cannibal self-interactions during freeze-in production. We find that the Lyman-$α$ bounds can be modified by a few orders of magnitude in the sub-MeV region and frozen-in dark matter saturating the observed energy density can be as light as $\approx$ 1.9 (0.7) keV, compared to the $\approx$ 5.7 (1.9) keV warm dark matter limits determined from simulations. Interestingly, a secondary phase of cooling due to simultaneously efficient inverse cannibal- and decay-processes can dominate the modifications of Lyman-$α$ bounds, rather than self-thermalization via cannibal-reactions itself.
Comments12+2 pages, 5 figures
