Exciting dark matter and the INTEGRAL/SPI 511 keV signal
Exciting dark matter and the INTEGRAL/SPI 511 keV signal
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DOI：
10.1103/physrevd.76.083519
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发表时间：
2007-02
影响因子：
5
通讯作者：
D. Finkbeiner;N. Weiner
中科院分区：
文献类型：
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作者：
D. Finkbeiner;N. Weiner
我们提出了一个‘激发态’比基态高1-2 MeV的候选暗物质，它可以被碰撞激发，并通过e{sup+}e{sup-}对发射而失激。通过将其动能转换成对，这样的粒子可以产生内银河系国际伽马射线天体物理实验室/SPI观测到的511keV谱线的相当大一部分。只有一小部分候选暗物质有足够的能量来激发，而且这一比例随着银心半径的增加而急剧下降，自然产生了径向截止，正如观察到的那样。即使在KPC内部的散射概率是1%/哈勃时间，也有足够的能量产生在银河系凸起中观察到的每秒3x10对。我们指定了用于解释正电子信号的伪狄拉克费米子的参数，发现它主要湮没到e{sup+}e{sup-}，并在正确的遗迹密度下冻结。我们讨论了这个模型可能的观测结果。
We propose a dark matter candidate with an 'excited state' 1-2 MeV above the ground state, which may be collisionally excited and deexcites by e{sup +}e{sup -} pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction of the 511 keV line observed by the International Gamma-Ray Astrophysics Laboratory/SPI in the inner Milky Way. Only a small fraction of the dark matter candidates have sufficient energy to excite, and that fraction drops sharply with galactocentric radius, naturally yielding a radial cutoff, as observed. Even if the scattering probability in the inner kpc is <<1% per Hubble time, enough power is available to produce the {approx}3x10{sup 42} pairs per second observed in the galactic bulge. We specify the parameters of a pseudo-Dirac fermion designed to explain the positron signal, and find that it annihilates chiefly to e{sup +}e{sup -} and freezes out with the correct relic density. We discuss possible observational consequences of this model.