Reproducibility of Non-X-ray Background for the X-ray Imaging Spectrometer aboard Suzaku
Reproducibility of Non-X-ray Background for the X-ray Imaging Spectrometer aboard Suzaku
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DOI：
10.1093/pasj/60.sp1.s11
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发表时间：
2008-02
影响因子：
2.3
通讯作者：
N. Tawa;K. Hayashida;Masaaki Nagai;Hajime Nakamoto;H. Tsunemi;H. Yamaguchi;Y. Ishisaki;E. Miller-E.-Mill
中科院分区：
文献类型：
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作者：
N. Tawa;K. Hayashida;Masaaki Nagai;Hajime Nakamoto;H. Tsunemi;H. Yamaguchi;Y. Ishisaki;E. Miller-E.-Mill
朱雀号上的x射线成像光谱仪（XIS）系统的优点之一是其低而稳定的非x射线背景（NXB）。为了充分利用这一优势，对NXB光谱进行高精度建模，将其从源上观测的光谱中减去是很重要的。我们通过收集黑暗地球覆盖XIS视场时的XIS事件来构建NXB数据库。对于每个XIS， NXB数据的总曝光时间约为785 ks。研究发现，NXB抗计数率与“朱雀”牌硬x射线探测器的截止刚度和PIN上鉴别器（PIN- ud）计数率相关。因此，我们通过使用这些参数中的任何一个来为给定的源上观测建立NXB光谱模型，并且使用PIN-UD模型比使用截止刚度模型获得更好的NXB再现性。NXB数据每5ks曝光，每个XIS NXB在1-7 keV波段的重现性为4.55-5.63%，每个XIS NXB在5-12 keV波段的重现性为2.79-4.36%。这种NXB再现性远小于宇宙x射线背景在1-7 keV波段的空间波动，与5-12 keV波段的空间波动几乎相当。
One of the advantages of the X-ray Imaging Spectrometer (XIS) system on board Suzaku is its low and stable non-X-ray background (NXB). In order to make the best use of this advantage, modeling the NXB spectra with high accuracy is important to subtract them from the spectra of on-source observations. We construct an NXB database by collecting XIS events when the dark Earth covers the XIS FOV. The total exposure time of the NXB data is about 785 ks for each XIS. It is found that the count rate of the NXB anti-correlates with the cut-off-rigidity and correlates with the count rate of the PIN upper discriminator (PIN-UD) in Hard X-ray Detector on board Suzaku. We thus model the NXB spectrum for a given on-source observation by employing either of these parameters and obtain a better reproducibility of the NXB for the model with PIN-UD than that with the cut-off-rigidity. The reproducibility of the NXB model with PIN-UD is 4.55-5.63% for each XIS NXB in the 1-7 keV band and 2.79-4.36% for each XIS NXB in the 5-12 keV band for each 5 ks exposure of the NXB data. This NXB reproducibility is much smaller than the spatial fluctuation of the cosmic X-ray background in the 1-7 keV band, and is almost comparable to that in the 5-12 keV band.