A dynamic black hole corona in an active galaxy through X-ray reverberation mapping
A dynamic black hole corona in an active galaxy through X-ray reverberation mapping
复制标题
DOI：
10.1038/s41550-019-1002-x
复制
发表时间：
2020-01-20
期刊：
影响因子：
14.1
通讯作者：
Zogbhi, Abderahmen
中科院分区：
文献类型：
--
作者：
Alston, William N.;Fabian, Andrew C.;Zogbhi, Abderahmen
X射线混响回波被认为是在吸积超大质量黑洞周围强烈扭曲的时空中产生的。该信号使我们能够在空间上绘制内部吸积流（1,2）的几何形状（任何望远镜都无法在空间上解析该区域），并提供黑洞质量和自旋的直接测量。混响时间尺度由热 X 射线日冕的直接发射和吸积盘内边缘的再处理发射之间的光传播路径设定(3-6)。然而，黑洞质量、盘内半径和盘上方照明日冕的高度之间的混响信号存在固有的简并性。在这里，我们使用对高度可变的活动星系 IRAS 13224-3809 的长 X 射线观测来跟踪系统在一天 (7,8) 的时间尺度上演化时的混响信号。考虑到所有相对论效应，模型显示 X 射线日冕的高度随着光度的增加而增加，从而提供了内部吸积区域的动态视图。这种同步建模使我们能够打破固有的简并性，并获得对黑洞质量和自旋的独立的基于时间的估计。黑洞质量的不确定性与领先的光学混响方法相当(9)，这使得X射线混响成为一种强大的技术，特别是对于光学变异性较低的源(10)。对高度可变的活动星系的长期X射线观测的相对论模型表明，其X射线日冕的高度随着光度的增加而增加。 X 射线混响被证明是测量黑洞质量的强大技术。
X-ray reverberation echoes are assumed to be produced in the strongly distorted spacetime around accreting supermassive black holes. This signal allows us to spatially map the geometry of the inner accretion flow(1,2)-a region that cannot yet be spatially resolved by any telescope-and provides a direct measure of the black hole mass and spin. The reverberation timescale is set by the light travel path between the direct emission from a hot X-ray corona and the reprocessed emission from the inner edge of the accretion disk(3-6). However, there is an inherent degeneracy in the reverberation signal between black hole mass, inner disk radius and height of the illuminating corona above the disk. Here we use a long X-ray observation of the highly variable active galaxy IRAS 13224-3809 to track the reverberation signal as the system evolves on timescales of a day(7,8). With the inclusion of all the relativistic effects, modelling reveals that the height of the X-ray corona increases with increasing luminosity, providing a dynamic view of the inner accretion region. This simultaneous modelling allows us to break the inherent degeneracies and obtain an independent timing-based estimate for the mass and spin of the black hole. The uncertainty on black hole mass is comparable to the leading optical reverberation method(9), making X-ray reverberation a powerful technique, particularly for sources with low optical variability(10).Relativistic modelling of long X-ray observations of a highly variable active galaxy reveals that the height of its X-ray corona increases with increasing luminosity. X-ray reverberation is shown to be a powerful technique to measure black hole masses.