Constraints on light bending and reflection from the hard X-ray background
Constraints on light bending and reflection from the hard X-ray background
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DOI：
10.1111/j.1365-2966.2007.12462.x
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发表时间：
2007-09
影响因子：
4.8
通讯作者：
P. Gandhi;Ac Fabian;T. Suebsuwong;J. Malzac;G. Miniutti;R. Wilman
中科院分区：
文献类型：
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作者：
P. Gandhi;Ac Fabian;T. Suebsuwong;J. Malzac;G. Miniutti;R. Wilman
由于强引力引起的光弯曲最近被用来解释某些吸积黑洞中不同波段之间的变化和通量相关性。光弯曲的一个特征是反射主导的光谱，特别是当光子源位于事件视界几个引力半径内的引力势最深处时。我们使用硬X射线背景的光谱，以限制这种反射占主导地位的源的流行。我们首先强调反射的需要，并探讨现实光谱的宽带特性，包括光弯曲。然后，我们使用这些光谱，结合所观察到的2-10 keV的活动星系核分布，演化和遮蔽功能，以预测硬X射线背景光谱超过3-100 keV，并提供限制的反射占主导地位的对象的分数，取决于光子源的高度。我们的研究结果允许一个宇宙学上显着的一部分，将强光弯曲的来源。基于耀斑的本征光度的光度函数推导和讨论的影响。我们讨论了未来硬X射线任务的前景，如新的X射线望远镜/非热能探测望远镜和Simbol-X，可以对这些源进行成像，并确认其峰值附近X射线背景的精确光谱形状，这对于限制光弯曲的普遍相关性很重要。
Light bending due to strong gravity has recently been invoked to explain variability and flux correlations between different bands in some accreting black holes. A characteristic feature of light bending is reflection-dominated spectra, especially if photon sources lie in the deepest parts of the gravitational potential within a few gravitational radii of the event horizon. We use the spectrum of the hard X-ray background in order to constrain the prevalence of such reflection-dominated sources. We first emphasize the need for reflection and explore the broad-band properties of realistic spectra that incorporate light bending. We then use these spectra, in conjunction with the observed 2-10 keV active galactic nucleus distribution, evolutionary and obscuration functions in order to predict the hard X-ray background spectrum over 3-100 keV, and provide limits on the fraction of reflection-dominated objects, dependent on the height of the photon sources. Our results allow for a cosmologically-significant fraction of sources that incorporate strong light bending. The luminosity function based on intrinsic flare luminosities is derived and implications discussed. We discuss prospects for future hard X-ray missions such as New X-ray Telescope/Non-thermal Energy eXploration Telescope and Simbol-X that can image such sources as well as confirm the precise spectral shape of the X-ray background near its peak, important for constraining the universal relevance of light bending.