Cherenkov Telescope Array sensitivity to the putative millisecond pulsar population responsible for the Galactic Centre excess
Cherenkov Telescope Array sensitivity to the putative millisecond pulsar population responsible for the Galactic Centre excess
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DOI：
10.1093/mnras/stab1450
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发表时间：
2021-02
影响因子：
4.8
通讯作者：
O. Macias;Harm van Leijen-Harm-van Leijen-2126227530;D. Song;S. Ando;S. Horiuchi;R. Crocker
中科院分区：
文献类型：
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作者：
O. Macias;Harm van Leijen-Harm-van Leijen-2126227530;D. Song;S. Ando;S. Horiuchi;R. Crocker
对费米银河系中心γ射线过剩的主要解释是来自银河系核球中尚未解决的毫秒双星（MSP）的扩展发射。这样的粒子群，沿着瞬发γ射线，也会向星际介质中注入大量的电子/正电子（e±）。这些e±可能会将周围的光子逆康普顿（IC）散射成γ射线，这些γ射线落在即将到来的切伦科夫望远镜阵列（CTA）的灵敏度范围内。在本文中，我们通过对TeV尺度γ射线能量下银河漫发射模型的系统不确定性进行现实的估计，来检查CTA对该特征的探测潜力。我们预测，如果e±注入光谱比E−2更难，CTA有可能稳健地发现一个假定的银河系凸起MSP种群的IC签名，足以解释银河系中心过量的e±注入效率在1.22%-74.1%之间，或更高，这取决于银河系漫发射成分的错误建模水平。另一方面，对于比E−2.5更软的光谱，可靠的CTA检测将需要非物理上大的e±注入效率${\gtrsim} 158{{\rm %}}$。然而，即使是这种悲观的结论可能会避免在合理的事件，MSP观测和/或建模的不确定性可以减少。我们进一步发现，在检测到IC信号的情况下，CTA可以成功区分MSP和辐射e±的暗物质起源。
The leading explanation of the Fermi Galactic Centre γ-ray excess is the extended emission from an unresolved population of millisecond pulsars (MSPs) in the Galactic bulge. Such a population would, along with the prompt γ-rays, also inject large quantities of electrons/positrons (e±) into the interstellar medium. These e± could potentially inverse-Compton (IC) scatter ambient photons into γ-rays that fall within the sensitivity range of the upcoming Cherenkov Telescope Array (CTA). In this article, we examine the detection potential of CTA to this signature by making a realistic estimation of the systematic uncertainties on the Galactic diffuse emission model at TeV-scale γ-ray energies. We forecast that, in the event that e± injection spectra are harder than E−2, CTA has the potential to robustly discover the IC signature of a putative Galactic bulge MSP population sufficient to explain the Galactic Centre excess for e± injection efficiencies in the range of ≈2.9–74.1 per cent, or higher, depending on the level of mismodelling of the Galactic diffuse emission components. On the other hand, for spectra softer than E−2.5, a reliable CTA detection would require an unphysically large e± injection efficiency of ${\gtrsim} 158{{\ \rm per\ cent}}$. However, even this pessimistic conclusion may be avoided in the plausible event that MSP observational and/or modelling uncertainties can be reduced. We further find that, in the event that an IC signal were detected, CTA can successfully discriminate between an MSP and a dark matter origin for the radiating e±.