论文标题
考虑运动能够抵消二进制AGN的考虑因素
Considerations for the Observability of Kinematically Offset Binary AGN
论文作者
论文摘要
预计未来几年的脉冲星计时阵列将检测到大型黑洞（MBH）二进制的重力波。尽管它们是二进制AGN的多通用器观察的有前途的来源，但在电磁调查中很少发现令人信服的候选人。一种识别候选者的方法是通过光谱调查来搜索宽发射线（BLS）的偏移或时间依赖的偏移，这可能是多普勒从二进制轨道运动转移的特征。在这项研究中，我们预测了应该可以在运动学上检测到的MBH二进制文件的参数空间。在要求二元间隔足够大以使BL区域保持与AGN之一的相关性之间，但也足够小，以使它们的轨道速度可以检测到，这是一个微妙的权衡。我们发现，对于低质量次级AGN，运动学签名只能观察到，总质量高于$ 10^8 m_ \ odot $，而分隔在0.1到1 pc之间。我们激励我们对运动偏移灵敏度的使用量为$ 10^3 $ km/s，以及对更换$ 10^2 $ km/s的偏移的敏感性。对于这些参数，爱丁顿的比率为0.1，我们发现0.5％的二进制文件具有可检测到的偏移，只有0.03％的二进制文件具有可检测的速度变化。总体而言，应预期的运动学二进制签名在$ 10^4 $ agn中不到1个。更好地表征BLS的内在变异性对于理解和审查MBH二进制候选者至关重要。这需要在各种时间尺度上的大量AGN种群的多上述光谱。
The gravitational waves from Massive black-hole (MBH) binaries are expected to be detected by pulsar timing arrays in the next few years. While they are a promising source for multimessenger observations as binary AGN, few convincing candidates have been identified in electromagnetic surveys. One approach to identifying candidates has been through spectroscopic surveys searching for offsets or time-dependent offsets of broad emission lines (BLs), which may be characteristic of Doppler shifts from binary orbital motion. In this study, we predict the parameter space of MBH binaries that should be kinematically detectable. There is a delicate trade-off between requiring binary separations to be large enough for BL regions to remain attached to one of the AGN, but also small enough such that their orbital velocity is detectable. We find that kinematic signatures are only observable for the lower-mass secondary AGN, for binaries with total-masses above about $10^8 M_\odot$, and separations between 0.1 and 1 pc. We motivate our usage of a kinematic-offset sensitivity of $10^3$ km/s, and a sensitivity to changing offsets of $10^2$ km/s. With these parameters, and an Eddington ratio of 0.1, we find that 0.5% of binaries have detectable offsets, and only 0.03% have detectable velocity changes. Overall, kinematic binary signatures should be expected in fewer than one in $10^4$ AGN. Better characterizing the intrinsic variability of BLs is crucial to understanding and vetting MBH binary candidates. This requires multi-epoch spectroscopy of large populations of AGN over a variety of timescales.
