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arXiv 1402.3591astro-ph.HE
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从硬X射线透视软X射线过剩

The hard X-ray perspective on the soft X-ray excess

Ranjan V. Vasudevan, Richard F. Mushotzky, Christopher S. Reynolds, Andrew C. Fabian, Anne M. Lohfink, Abderahmen Zoghbi, Luigi C. Gallo, Dominic Walton

摘要:

许多活动星系核(AGN)的X射线谱在1 keV以下都表现出“软过剩”,其物理来源尚不清楚。不同的模型已经被提出来解释它,包括X射线从吸积盘内部的电离反射,电离风/吸收器和康普顿化。电离反射模型表明,软过剩的突出和康普顿反射峰强度高于10 keV之间存在自然联系,但尚不清楚其他软X射线候选模型预计会产生什么样的硬X射线特征。此外,直到最近才能获得区分这些模型所需的软和硬X射线发射的高质量同时测量,但即将到来的XMM-NuSTAR联合计划恰恰提供了这一机会。在本文中,我们使用两个候选软过量模型作为输入,对XMM+NuSTAR观测的模拟进行了广泛的分析,以确定此类活动是否可以通过同时使用硬X射线和软X射线观测来消除它们之间的歧义。模拟的光谱与最简单的黑体和中性反射的“观察者模型”相拟合,以消除软过度和硬过度的强度。硬过量的强度相对于软过量强度的曲线图提供了诊断曲线图,其允许使用当前最先进的和下一代硬X射线使能的观测站在各个源和样品中确定软过量产生机制。这种方法可以直接扩展到其他候选模型的软过剩。

英文摘要:

The X-ray spectra of many active galactic nuclei (AGN) exhibit a `soft excess' below 1keV, whose physical origin remains unclear. Diverse models have been suggested to account for it, including ionised reflection of X-rays from the inner part of the accretion disc, ionised winds/absorbers, and Comptonisation. The ionised reflection model suggests a natural link between the prominence of the soft excess and the Compton reflection hump strength above 10keV, but it has not been clear what hard X-ray signatures, if any, are expected from the other soft X-ray candidate models. Additionally, it has not been possible up until recently to obtain high-quality simultaneous measurements of both soft and hard X-ray emission necessary to distinguish these models, but upcoming joint XMM-NuSTAR programmes provide precisely this opportunity. In this paper, we present an extensive analysis of simulations of XMM+NuSTAR observations, using two candidate soft excess models as inputs, to determine whether such campaigns can disambiguate between them by using hard and soft X-ray observations in tandem. The simulated spectra are fit with the simplest "observer's model" of a black body and neutral reflection to characterise the strength of the soft and hard excesses. A plot of the strength of the hard excess against the soft excess strength provides a diagnostic plot which allows the soft excess production mechanism to be determined in individual sources and samples using current state-of-the-art and next generation hard X-ray enabled observatories. This approach can be straightforwardly extended to other candidate models for the soft excess.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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