论文标题
分子云电离对暗物质电子散射的限制
Constraints on Dark Matter-Electron Scattering from Molecular Cloud Ionization
论文作者
论文摘要
我们证明，$ \ text {h} _2 $ by暗物质在密集的分子云中对$ \ text {h} _2 $可以用电子对暗物质的散射强度提供强大的约束。分子云具有较高的紫外线衰减，使它们免受紫外线和X射线光子的影响。它们的化学和热进化受低能宇宙射线的控制。带有质量$ \ gtrsim的暗物质4 $ meV可以电离$ \ text {h} _2 $，从而有助于观察到的电离率。我们要求在diffuse molecular云中，暗物质诱导的电离率$ \ text {h} _2 $不超过观察到的宇宙射线电离速率，$ζ^{\ text {h} _2} $，以及诸如Taurus云复合物中的L1551等密集的分子云。这使我们能够在DM电子横截面（$ \barσ_e$）上放置强大的约束，并补充了现有的天体物理约束，并探测了陆地和地下直接检测实验会失去敏感性的强烈相互作用的参数空间。我们表明，分子云与计划的气球和基于卫星的实验的约束将强烈限制与电子与电子强烈相互作用的暗物质的分数丰度。我们评论未来的建模和观察性努力，这些努力可能会改善我们的界限。
We demonstrate that ionization of $\text{H}_2$ by dark matter in dense molecular clouds can provide strong constraints on the scattering strength of dark matter with electrons. Molecular clouds have high UV-optical attenuation, shielding them from ultraviolet and X-ray photons. Their chemical and thermal evolution are governed by low-energy cosmic rays. Dark matter with mass $\gtrsim 4$ MeV can ionize $\text{H}_2$, contributing to the observed ionization rate. We require that the dark matter-induced ionization rate of $\text{H}_2$ not exceed the observed cosmic ray ionization rate, $ζ^{\text{H}_2}$, in diffuse molecular clouds as well as dense molecular clouds such as L1551 in the Taurus cloud complex. This allow us to place strong constraints on the DM-electron cross section, $\barσ_e$, that complement existing astrophysical constraints and probe the strongly interacting parameter space where terrestrial and underground direct detection experiments lose sensitivity. We show that constraints from molecular clouds combined with planned balloon and satellite-based experiments would strongly constrain the fractional abundance of dark matter that interacts strongly with electrons. We comment on future modeling and observational efforts that may improve our bounds.
