Binary black hole signatures in polarized light curves
Binary black hole signatures in polarized light curves
复制标题
偏振光曲线中的二元黑洞特征
DOI：
10.1093/mnras/stab2893
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发表时间：
2021
影响因子：
4.8
通讯作者：
Ho, Luis C
中科院分区：
文献类型：
--
作者：
Dotti, Massimo;Bonetti, Matteo;D’Orazio, Daniel J;Haiman, Zoltán;Ho, Luis C
具有周期性光曲线的可变活动星系核被认为是大质量黑洞双星（MBHB）的候选者。在这种情况下，周期性可能是由于发射光的相对论多普勒增强。这个假设可以通过散射偏振光的时序来验证。根据I型核的极化研究结果和环双星盘MBHBs的动力学研究结果，我们假设了一个共面赤道散射环，由于散射角、多普勒增强水平和视距时间延迟不同，其元素对总极化通量的贡献不同。我们发现在MBHB存在的情况下，偏振度和偏振位角都有周期性调制。偏振角围绕投影的MBHB轨道椭圆的半轴振荡，其频率等于双星的轨道频率（对于较大的散射屏半径），或两倍于这个值（对于较小的散射结构）。这些独特的特征可以用来探测周期性MBHB候选者的性质，并编制最有希望的亚pc MBHB的目录。在引力波（GW）探测到的mbhb中识别这种极化特征将极大地增加有关源的物理信息量，从而可以测量双星分量的单个质量，以及天空中节点线的方向，甚至对于单色的GW信号也是如此。
Variable active galactic nuclei showing periodic light curves have been proposed as massive black hole binary (MBHB) candidates. In such scenarios, the periodicity can be due to relativistic Doppler-boosting of the emitted light. This hypothesis can be tested through the timing of scattered polarized light. Following the results of polarization studies in type I nuclei and of dynamical studies of MBHBs with circumbinary discs, we assume a coplanar equatorial scattering ring, whose elements contribute differently to the total polarized flux, due to different scattering angles, levels of Doppler boost, and line-of-sight time delays. We find that in the presence of an MBHB, both the degree of polarization and the polarization position angle have periodic modulations. The polarization angle oscillates around the semiminor axis of the projected MBHB orbital ellipse, with a frequency equal either to the binary’s orbital frequency (for large scattering screen radii), or twice this value (for smaller scattering structures). These distinctive features can be used to probe the nature of periodic MBHB candidates and to compile catalogues of the most promising sub-pc MBHBs. The identification of such polarization features in gravitational-wave (GW) detected MBHBs would enormously increase the amount of physical information about the sources, allowing the measurement of the individual masses of the binary components, and the orientation of the line of nodes on the sky, even for monochromatic GW signals.