Multi-messenger Approaches to Supermassive Black Hole Binary Detection and Parameter Estimation: Implications for Nanohertz Gravitational Wave Searches with Pulsar Timing Arrays
Multi-messenger Approaches to Supermassive Black Hole Binary Detection and Parameter Estimation: Implications for Nanohertz Gravitational Wave Searches with Pulsar Timing Arrays
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DOI：
10.3847/1538-4357/ac1da9
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
Tingting Liu;S. Vigeland
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作者：
Tingting Liu;S. Vigeland
脉冲星定时阵列(PTA)实验对纳赫兹频率范围内的引力波(GW)越来越敏感，其中主要的天体物理源是超大质量黑洞双星(SMBHBs)，预计它们将在星系合并后形成。其中一些单独的SMBHBs可能为活动星系核提供能量，因此它们的二进制参数可以通过电磁获得，这使得应用电磁(EM)信息来帮助搜索PTA数据中的GW信号成为可能。在这项工作中，我们通过在模拟的PTA数据集上执行模拟数据分析来研究这种EM信息搜索对二进制检测和参数估计的影响。我们发现，通过应用EM先验，一些原本具有边缘或亚阈值可检测性的注入信号的贝叶斯因子(即，贝叶斯因子∼1)可以增加几倍到一个数量级，从而在不知情的搜索没有找到任何信号的情况下，EM通知的目标搜索能够找到信号的线索。此外，通过结合EM和GW数据，可以实现参数估计的全面改进，而无论源的天空位置或GW频率如何。我们讨论了对患有PTA的SMBHBs的多信使研究的意义。
Pulsar timing array (PTA) experiments are becoming increasingly sensitive to gravitational waves (GWs) in the nanohertz frequency range, where the main astrophysical sources are supermassive black hole binaries (SMBHBs), which are expected to form following galaxy mergers. Some of these individual SMBHBs may power active galactic nuclei, and thus their binary parameters could be obtained electromagnetically, which makes it possible to apply electromagnetic (EM) information to aid the search for a GW signal in PTA data. In this work, we investigate the effects of such an EM-informed search on binary detection and parameter estimation by performing mock data analyses on simulated PTA data sets. We find that by applying EM priors, the Bayes factor of some injected signals with originally marginal or sub-threshold detectability (i.e., Bayes factor ∼1) can increase by a factor of a few to an order of magnitude, and thus an EM-informed targeted search is able to find hints of a signal when an uninformed search fails to find any. Additionally, by combining EM and GW data, one can achieve an overall improvement in parameter estimation, regardless of the source’s sky location or GW frequency. We discuss the implications for the multi-messenger studies of SMBHBs with PTAs.