Decaying axinolike dark matter: Discriminative solution to small-scale issues
Decaying axinolike dark matter: Discriminative solution to small-scale issues
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DOI：
10.1103/physrevd.99.023511
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发表时间：
2018-06
影响因子：
5
通讯作者：
K. J. Bae;Ayuki Kamada;Hee Jung Kim
中科院分区：
文献类型：
--
作者：
K. J. Bae;Ayuki Kamada;Hee Jung Kim
最新的莱曼-$\alpha$森林数据严重限制了传统的温暖的暗物质解决方案，在冷暗物质范式的小规模问题。另据报道，不受约束的天体物理过程可能会解决这些问题。针对这种情况，我们重新审视了衰变暗物质的问题解决方案，讨论了可能的签名，以区分衰变暗物质从天体物理过程作为一个小尺度问题的解决方案。我们考虑类轴子粒子（ALPino）衰变为类轴子粒子（ALP）和引力子，其寿命大约在宇宙年龄附近。ALPino的质量低于PeV，比引力子的质量稍大（$\Delta m/m\sim 10^{-4}$），因此暗物质的丰度在ALPino衰变后实际上不会改变。另一方面，由ALPino衰变产生的引力子获得了$\sim 30 \，{\rm km / s}$的反冲速度，这比矮星系的圆速度大得多，足以影响它们的暗物质分布。莱曼-$\alpha$森林的限制被解除，因为只有一小部分（$\sim10$%）的暗物质的经验，在当时的衰变。因此，衰变的暗物质被提升为小规模问题的可行解决方案。ALPino遗迹的丰度主要取决于最轻的普通超对称粒子的衰变。在银河系磁场的作用下，由ALPino衰变产生的单色ALP辐射被转换为$\sim 50 \，{\rmGeV}$光子。伽马射线通量的形态显示了该模型与直接衰变为光子的衰变暗物质相比的独特特征。一旦被探测到，这种独特的信号就能将小尺度问题的衰变暗物质解决方案与不受约束的天体物理过程区分开来。
The latest Lyman-$\alpha$ forest data severely constrain the conventional warm dark matter solution to small-scale issues in the cold dark matter paradigm. It has been also reported that unconstrained astrophysical processes may address the issues. In response to this situation, we revisit the decaying dark matter solution to the issues, discussing possible signatures to discriminate decaying dark matter from astrophysical processes as a solution to small-scale issues. We consider an axinolike particle (ALPino) decaying into an axionlike particle (ALP) and gravitino with the lifetime around the age of the Universe. The ALPino mass is sub-PeV and slightly ($\Delta m/m\sim 10^{-4}$) larger than the gravitino mass, and thus the dark matter abundance does not alter virtually after the ALPino decays. On the other hand, the gravitino produced from the ALPino decay obtains a kick velocity of $\sim 30 \,{\rm km / s}$, which is sufficiently larger than a circular velocity of dwarf galaxies to impact their dark matter distributions. The Lyman-$\alpha$ forest constraints are relieved since only a small fraction ($\sim10$%) of dark matter experiences the decay at that time. Decaying dark matter is thus promoted to a viable solution to small-scale issues. The ALPino relic abundance is determined predominantly by the decay of the lightest ordinary supersymmetric particle. The monochromatic ALP emission from the ALPino decay is converted to $\sim 50 \,{\rm GeV}$ photon under the Galactic magnetic field. The morphology of the gamma-ray flux shows a distinctive feature of the model when compared to decaying dark matter that directly decays into photons. Once detected, such distinctive signals discriminate the decaying dark matter solution to small-scale issues from unconstrained astrophysical processes.