Chandra ACIS-I particle background: an analytical model
Chandra ACIS-I particle background: an analytical model
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DOI：
10.1051/0004-6361/201423443
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发表时间：
2014-04
影响因子：
6.5
通讯作者：
I. Bartalucci;P. Mazzotta;H. Bourdin;A. Vikhlinin
中科院分区：
文献类型：
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作者：
I. Bartalucci;P. Mazzotta;H. Bourdin;A. Vikhlinin
目标。x射线扩展源的成像和光谱学需要对空间未解析的背景信号进行适当的表征。这个背景包括天空和仪器成分，每一个都有其适当的空间和光谱行为特征。虽然在以前的工作中已经对x射线天空背景进行了广泛的研究，但在这里，我们分析和模拟了钱德拉x射线天文台上的acis - 1探测器在非常微弱模式下的仪器背景。方法。由于高能粒子与探测器的相互作用，ACIS-I仪器背景的光谱特征是几个荧光发射线叠加在一个连续体上。为了将其通量从任何天空分量中分离出来，我们将一个连续体的分析模型拟合到在非常微弱的模式下进行的观测中，并将探测器放置在屏蔽天空的存放位置，并从2001年开始收集了8年的时间。其余的发射线则与同一时期的空天观测结果相匹配。我们发现了11条发射线。分析这些线的振幅、能量和宽度的空间变化，进一步使我们能够推断出其中的三条线可能是由于在框架存储中产生的能量校正伪影。结果。我们提供了一个分析模型，预测仪器背景的精度为连续体的2%和线的5%。我们使用这个模型来测量钱德拉南部深场未解决的宇宙x射线背景的通量。我们得到[1 2]keV波段的通量为10:2 +0:5 0:4 10 13 erg cm 2°=2 s 1， [2 8] keV波段的通量为（3:8 0:2）10 12 erg cm 2°=2 s 1。
Aims. Imaging and spectroscopy of X-ray extended sources require a proper characterisation of a spatially unresolved background signal. This background includes sky and instrumental components, each of which are characterised by its proper spatial and spectral behaviour. While the X-ray sky background has been extensively studied in previous work, here we analyse and model the instrumental background of the ACIS-I detector on board the Chandra X-ray observatory in very faint mode. Methods. Caused by interaction of highly energetic particles with the detector, the ACIS-I instrumental background is spectrally characterised by the superimposition of several fluorescence emission lines onto a continuum. To isolate its flux from any sky component, we fitted an analytical model of the continuum to observations performed in very faint mode with the detector in the stowed position shielded from the sky, and gathered over the eight-year period starting in 2001. The remaining emission lines were fitted to blank-sky observations of the same period. We found 11 emission lines. Analysing the spatial variation of the amplitude, energy and width of these lines has further allowed us to infer that three lines of these are presumably due to an energy correction artefact produced in the frame store. Results. We provide an analytical model that predicts the instrumental background with a precision of 2% in the continuum and 5% in the lines. We use this model to measure the flux of the unresolved cosmic X-ray background in the Chandra deep field south. We obtain a flux of 10:2 +0:5 0:4 10 13 erg cm 2 deg =2 s 1 for the [1 2] keV band and (3:8 0:2) 10 12 erg cm 2 deg =2 s 1 for the [2 8] keV band.