活动星系核喷流进动的物理机制分析

Analyses of physical mechanism of jet precession in active galactic nuclei

为了研究活动星系核喷流进动的物理机制,从文献中收集到23个有喷流进动周期(P)、B波段绝对星等(Mabs)和黑洞质量(Mbh)数据的活动星系核组成样本.用样本检验吸积盘驱动中心黑洞和喷流进动的盘致进动模型,观测到数据整体上符合理论预期的P、Mabs和Mbh之间的关系,但数据的弥散度较大,吸积盘的黏滞参数需取较大范围才能使理论范围覆盖所有的样本源.喷流进动也可能是由于星系核中心存在超大质量双黑洞.在此双黑洞模型下估算了样本源中双黑洞的距离,并将10个样本源的双黑洞距离和从文献中得到的星系核宽线区尺度对比,显示喷流进动周期大于106年的样本源的双黑洞距离可能大于星系核宽线区尺度.因此通过喷流进动的观测结果可以搜寻超大质量双黑洞候选体和限制双黑洞的参数.高质量的反响映射监测等进一步观测有望检验超大质量双黑洞系统的存在,帮助揭示喷流进动的物理机制.

In order to investigate the mechanism of jet precession in active galactic nuclei(AGNs),we compiled a sample of 23 AGNs with jet precession periods(P),absolute magnitudes for the optical band(M abs),and black hole masses(M bh).The sample was used to test the model in which an accretion disk drives the precession of the central black hole and the jet.The observational data generally agree with the theoretical relationship among P,M abs and M bh,but with significant dispersion.A large range of accretion disk viscosity parameters are needed for the theoretical prediction to cover all the sample sources.The jet precession may also result from supermassive black hole binaries(SMBHBs).Under this black hole binary model,binary separations were estimated for all the sources in our sample.In addition,for 10 sample sources,the binary separation was compared with the size of the AGN broad line region.Results show that the former can exceed the latter in sample sources with P>106 years.Through observational results of jet precession,we can search for SMBHB candidates and constrain their parameters.Finally,further observations such as high-fidelity reverberation mapping campaigns are expected to diagnose the presence of SMBHBs and help unveil the physical mechanism of jet precession in AGNs.