用SPI约束DM属性
Constraining DM properties with SPI
摘要：
利用国际伽玛射线天体物理实验室（INTEGRAL）的高分辨率光谱仪SPI，对银河系暗物质晕中质量在40 keV < M_DM <14 MeV范围内的暗物质衰变产生的一条谱线进行了探测。为了区分DM衰变线从SPI背景光谱中发现的众多仪器线，我们研究了线信号的强度对SPI指向的方向朝向银河系中心的偏移的依赖性。在对银河系内部DM密度分布的不确定性进行严格分析后，我们发现，当银河系中心的偏移量从0增加到180度时，DM衰变线的强度至少会降低3倍。我们发现，这样一个显着的变化，整个天空的线通量没有观察到任何线，检测到的显着性高于3西格玛的SPI背景光谱。仅对于未识别的谱线，不排除可能的DM衰变起源，其具有低（~3 sigma）显著性或与仪器的位置一致。在从20千电子伏到7兆电子伏的能量区间，我们得到的DM衰变线通量的限制，暗示（非）检测的DM衰变线。对于一个特定的DM候选人，不育中微子的质量MDM，我们推导出一个绑定的混合角。
英文摘要：
Using the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), we search for a spectral line produced by a dark matter(DM) particle with a mass in the range 40keV < M_DM < 14MeV, decaying in the DM halo of the Milky Way. To distinguish the DM decay line from numerous instrumental lines found in the SPI background spectrum, we study the dependence of the intensity of the line signal on the offset of the SPI pointing from the direction toward the Galactic Centre. After a critical analysis of the uncertainties of the DM density profile in the inner Galaxy, we find that the intensity of the DM decay line should decrease by at least a factor of 3 when the offset from the Galactic Centre increases from 0 to 180 degrees. We find that such a pronounced variation of the line flux across the sky is not observed for any line, detected with a significance higher than 3 sigma in the SPI background spectrum. Possible DM decay origin is not ruled out only for the unidentified spectral lines, having low (~3 sigma) significance or coinciding in position with the instrumental ones. In the energy interval from 20 keV to 7 MeV, we derive restrictions on the DM decay line flux, implied by the (non-)detection of the DM decay line. For a particular DM candidate, the sterile neutrino of mass MDM, we derive a bound on the mixing angle.
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