Observation of the Crab Nebula with LHAASO-KM2A − a performance study
Observation of the Crab Nebula with LHAASO-KM2A − a performance study
复制标题
使用 LHAASO-KM2A 观测蟹状星云 — 性能研究
DOI：
10.1088/1674-1137/abd01b
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发表时间：
2021
影响因子：
3.6
通讯作者：
X. L. C
中科院分区：
文献类型：
--
作者：
F. A. Aharonian;Q. An;Axikegu;L. X. Bai;Bai Yibing;Y. W. Bao;D. Bastieri;X. J. Bi;Y. J. Bi;H. Cai;J. T. Cai;Zihuang Cao;J. F. Chang;J. F. Chang;X. C. Chang;B. M. Chen;J. Chen;L. Chen;M. J. Chen;M. L. Chen;Q. H. Chen;Sina Chen;S. Z. Chen;T. L. Chen;X. L. C
大高海拔空气簇射观测站（LHAASO）的子阵列——平方千米阵列（KM2A），主要旨在对北半球大部分天空进行观测，以搜寻10 TeV以上能量的伽马射线源。尽管探测器仍在建设中，但自2019年底以来，KM2A阵列的一半已稳定运行。在本文中，我们介绍了KM2A数据分析流程以及对蟹状星云（甚高能伽马射线天文学中的标准烛光）的首次观测。通过分析2019年12月至2020年5月136个有效天的KM2A数据，我们在10 - 100 TeV和100 TeV以上这两个能量区间均探测到来自蟹状星云的高显著性伽马射线信号。通过这些观测，我们测试了探测器性能，包括角分辨率、指向精度和宇宙射线本底排除能力。在10 - 250 TeV能量区间内，蟹状星云的能谱与单一幂律函数dN/dE = (1.13 ± 0.05 ± 0.08 )×10⁻¹² (E/20 TeV)⁻².⁶⁵ cm⁻² s⁻¹ TeV⁻¹拟合良好。这与其他实验先前的测量结果一致。这开启了0.1 PeV以上伽马射线天文学的新窗口，通过该窗口，诸如宇宙拍电子伏加速器等新的超高能伽马射线现象或许能够被发现。
A sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV. Even though the detector construction is still underway, half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the KM2A data analysis pipeline and the first observation of the Crab Nebula, a standard candle in very high energy γ-ray astronomy. We detect γ-ray signals from the Crab Nebula in both energy ranges of 10 100 TeV and 100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance, including angular resolution, pointing accuracy and cosmic-ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE = (1.13 0.05 0.08 ) 10 (E/20 TeV) cm s TeV . It is consistent with previous measurements by other experiments. This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena, such as cosmic PeVatrons, might be discovered.