Consistent explanation for the cosmic-ray positron excess in p-wave
Consistent explanation for the cosmic-ray positron excess in p-wave
复制标题
对 p 波宇宙射线正电子过剩的一致解释
DOI：
10.1088/1475-7516/2021/09/005
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发表时间：
2021
影响因子：
6.4
通讯作者：
Zhou Yu-Feng
中科院分区：
文献类型：
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作者：
Ding Yu-Chen;Ku Yu-Lin;Wei Chun-Cheng;Zhou Yu-Feng
索默菲尔德增强暗物质（DM）通过s波湮灭被广泛认为是对观测到的宇宙射线（CR）正电子过剩和DM热遗迹密度的一致解释。然而，由于s波索默菲尔德增强湮灭截面随着DM速度的减小而单调增大，矮球卫星星系（dSphs）和宇宙微波背景（CMB）的伽马射线数据出现了严重的约束，因为相关的典型DM速度甚至低于银河系晕中的速度。在这项工作中，我们考虑了索默菲尔德增强的p波DM湮灭，其中DM湮灭截面在一定速度下可以增强，但最终在DM速度变得非常低时被高度抑制。我们计算了15个附近的dsph的sommerfield增强p波DM湮灭的速度相关天体物理因子（j因子）。以DM湮灭到4μ的通道为例，我们发现该机制在某些参数区域可以解释CR正电子过剩和DM遗迹密度，同时兼容Fermi-LAT测量的dSphs伽马射线和PLANCK测量的CMB的约束。
Sommerfeld-enhanced dark matter (DM) annihilation through s-wave has been widely considered as a consistent explanation for both the observed cosmic-ray (CR) positron excess and the DM thermal relic density. However, as the s-wave Sommerfeld-enhanced annihilation cross section increases monotonically with decreasing DM velocity, severe constraints appear from the data of gamma rays from dwarf spheroidal satellite galaxies (dSphs) and the cosmic microwave background (CMB), as the relevant typical DM velocities are even lower than that in the Galactic halo. In this work, we consider Sommerfeld-enhanced p-wave DM annihilation where the DM annihilation cross section can be enhanced at certain velocities but eventually be highly suppressed when the DM velocities become extremely low. We calculate the velocity-dependent astrophysics factors (J-factors) for the Sommerfeld-enhanced p-wave DM annihilation for fifteen nearby dSphs. Taking the channel of DM annihilating into 4μ through two light mediators as an example, we show that there are parameter regions where this mechanism can account for the CR positron excess and the DM relic density, while being compatible with the constraints from dSphs gamma rays measured by Fermi-LAT and that from the CMB measured by PLANCK.