Millisecond pulsars cannot account for the inner Galaxy’s GeV excess
Millisecond pulsars cannot account for the inner Galaxy’s GeV excess
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DOI：
10.1103/physrevd.88.083009
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发表时间：
2013-05
影响因子：
5
通讯作者：
D. Hooper;I. Cholis;T. Linden;J. Siegal-Gaskins;T. Slatyer
中科院分区：
文献类型：
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作者：
D. Hooper;I. Cholis;T. Linden;J. Siegal-Gaskins;T. Slatyer
利用费米伽马射线太空望远镜的数据，从银河系中心方向识别出了伽马射线的空间扩展分量，峰值能量为1.2 -3 GeV。最近的研究表明，这种信号并不局限于银河系最里面的几百秒差距，而是从银河系中心延伸到至少10.3千秒差距。虽然这一信号的光谱、强度和角分布与湮灭暗物质的预测非常一致，但也有人认为，未解决的毫秒微扰星群可能是造成银河系内部过量GeV辐射的原因。在本文中，我们详细考虑了这种可能性。比较观测到的光谱形状的内银河系的GeV多余的费米从37毫秒的恒星测量的光谱，我们发现，这些来源表现出的光谱形状是太软，在亚GeV的能量，以适应这个信号。我们还构建了描述银河系毫秒脉冲星空间分布和亮度函数的种群模型。在考虑到费米源（包括已知的毫秒中微子源和可能是中微子源的未知源）的观测分布的限制后，我们发现毫秒中微子源只能占银河系内部GeV过剩的不超过10%。这些论点中的每一个都强烈反对将毫秒级脉冲作为该信号的源。
Using data from the Fermi Gamma-Ray Space Telescope, a spatially extended component of gamma rays has been identified from the direction of the Galactic center, peaking at energies of ∼2–3 GeV. More recently, it has been shown that this signal is not confined to the innermost hundreds of parsecs of the Galaxy, but instead extends to at least ∼3 kpc from the Galactic center. While the spectrum, intensity, and angular distribution of this signal is in good agreement with predictions from annihilating dark matter, it has also been suggested that a population of unresolved millisecond pulsars could be responsible for this excess GeV emission from the inner Galaxy. In this paper, we consider this later possibility in detail. Comparing the observed spectral shape of the inner Galaxy’s GeV excess to the spectrum measured from 37 millisecond pulsars by Fermi, we find that these sources exhibit a spectral shape that is much too soft at sub-GeV energies to accommodate this signal. We also construct population models to describe the spatial distribution and luminosity function of the Milky Way’s millisecond pulsars. After taking into account constraints from the observed distribution of Fermi sources (including both sources known to be millisecond pulsars, and unidentified sources which could be pulsars), we find that millisecond pulsars can account for no more than ∼10% of the inner Galaxy’s GeV excess. Each of these arguments strongly disfavor millisecond pulsars as the source of this signal.