ASCA and ROSAT observations of the QSF3 field: the X-ray background in the 0.1–7 keV band
ASCA and ROSAT observations of the QSF3 field: the X-ray background in the 0.1–7 keV band
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ASCA 和 ROSAT 对 QSF3 场的观测：0.1-7 keV 波段的 X 射线背景
DOI：
10.1093/mnras/285.3.449
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发表时间：
1995
影响因子：
4.8
通讯作者：
K. Gendreau
中科院分区：
文献类型：
--
作者：
L. Chen;A. Fabian;K. Gendreau
使用ASCA SIS和ROSAT PSPC的高光谱和空间分辨率数据研究了0.1至7 keV的X射线背景（XRB）。通过对ASCA和ROSAT数据的联合光谱拟合，分析了散射背景辐射和分辨源。XRB的光谱可以很好地拟合由一个单一的幂律从1到7千电子伏;总体而言，幂律模型的光子指数范围从1.4到1.5，并没有发现明显的过剩之间的1和3千电子伏。低于1 keV，模型变得更加复杂，涉及河外和银河系源的混合物。由于一些河外的贡献应该是从点源，我们已经审查了ASCA和ROSAT光谱的解决源单独：恒星源有一个很好的拟合热谱和两个活动星系核有一个更陡峭的幂律谱（光子指数约为3）; ROSAT解决的其他非恒星源的累积光谱也有一个比平均更陡峭的光谱。通过改变陡谱源（如类星体）对背景的贡献，将ASCA观测到的XRB谱和ROSAT积累的点源谱拟合在一起，我们发现它们在0.5- 2千电子伏波段的贡献小于30%，在2- 10千电子伏波段下降到10%以下。该部分由比10 ^{-15}$ \emperature亮几倍的光源提供（在0. 5 - 2 keV波段）。受我们的光谱拟合结果的约束，XRB的主要贡献者必须是具有相似平坦光谱的单个群体。
The X-ray background (XRB) from 0.1 to 7 keV has been studied using high spectral and spatial resolution data from the ASCA SIS and ROSAT PSPC. Analysing both the diffuse background radiation and resolved sources, we have carried out a series of joint spectral fits of the ASCA and ROSAT data. The spectrum of the XRB can be fit well by a single power-law from 1 to 7 keV; overall, the photon index of the power-law model ranges from 1.4 to 1.5, and no obvious excess is found between 1 and 3 keV. Below 1 keV, the models become more complicated and involve a mixture of extragalactic and Galactic sources. As some of the extragalactic contributions should be from point sources, we have examined the ASCA and ROSAT spectra of resolved sources individually: a stellar source having a well-fit thermal spectrum and two AGNs having a much steeper power-law spectrum (with photon index of about 3); the accumulated spectrum of other non-stellar sources resolved by ROSAT also has a steeper-than-average spectrum. Fitting the XRB spectrum observed by ASCA and the accumulated point source spectrum by ROSAT together by varying the contribution from steep spectrum sources, such as quasars, to the background, we find that they contribute less than 30 per cent in the 0.5--2 keV band and drop to below 10 per cent over 2--10 keV. This fraction is provided by sources brighter than a few times $10^{-15}$ \ergpercmpers (in the 0.5--2 keV band). Constrained by our spectral fitting results, the major contributor of the XRB must be a single population with similar flat spectra.