用费米LAT探测暗物质Gamma-Ray线
Hunting Dark Matter Gamma-Ray Lines with the Fermi LAT
摘要：
在暗物质粒子的湮灭或衰变中可以产生单色光子。在高能量下，在宇宙伽马射线谱中寻找这样的线特征基本上是无背景的，因为似乎合理的天体物理过程预计不会产生这样的信号。因此，对伽马射线线的观测将是暗物质的“确凿证据”，这使得寻找这种信号特别有吸引力。在不同的暗物质模型预测伽马射线线，局部超对称扩展的标准模型与小R-宇称违反和引力子LSP是特别感兴趣的，因为它提供了一个框架，原始核合成，引力子暗物质和热leptogenesis是自然一致的。利用两年的费米LAT数据，我们提出了一个专门的搜索来自暗物质湮灭或衰变在星系晕的伽马射线线。考虑到完整的探测器响应，并使用分箱的轮廓似然方法，我们搜索显着的线功能在天空的不同区域观察到的扩散通量的能谱。没有证据表明在5西格玛水平的线信号被发现的光子能量在1和300 GeV之间，和保守的界限上的暗物质衰变率和湮灭截面。引力子暗物质的存在下，小的R-宇称破坏的影响进行了讨论，以及我们的结果的影响，在大型强子对撞机上看到长寿命的中性伴子或staus的前景。
英文摘要：
Monochromatic photons could be produced in the annihilation or decay of dark matter particles. At high energies, the search for such line features in the cosmic gamma-ray spectrum is essentially background free because plausible astrophysical processes are not expected to produce such a signal. The observation of a gamma-ray line would hence be a `smoking-gun' signature for dark matter, making the search for such signals particularly attractive. Among the different dark matter models predicting gamma-ray lines, the local supersymmetric extension of the standard model with small R-parity violation and gravitino LSP is of particular interest because it provides a framework where primordial nucleosynthesis, gravitino dark matter and thermal leptogenesis are naturally consistent. Using the two-years Fermi LAT data, we present a dedicated search for gamma-ray lines coming from dark matter annihilation or decay in the Galactic halo. Taking into account the full detector response, and using a binned profile likelihood method, we search for significant line features in the energy spectrum of the diffuse flux observed in different regions of the sky. No evidence for a line signal at the 5-sigma level is found for photon energies between 1 and 300 GeV, and conservative bounds on dark matter decay rates and annihilation cross sections are presented. Implications for gravitino dark matter in presence of small R-parity violation are discussed, as well as the impact of our results on the prospect for seeing long-lived neutralinos or staus at the LHC.
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