CAREER: Multimessenger Astrophysics with Pulsar Timing Arrays in the Detection Era

最近，北美纳赫兹引力波天文台(NANOGrav)和脉冲星定时阵列(PTA)在世界各地的合作宣布了引力波背景(GWB)的证据，这表明PTA正在进入对纳赫兹频率范围内的引力波(GW)信号前所未有的敏感区域。PTA可以看到比宇宙微波背景辐射更早的时间，并允许我们以随机GWB的形式测量超大质量双星黑洞(SMBBH)的数量。背景的探测预示着单个源探测的到来，而此时维拉·C·鲁宾天文台和十年遗留空间和时间调查(LSST)计划开始获得一致和高质量的活动星系核(AGN)时间序列数据-恰好与PTA波段第一次单源探测的时代相一致。在这些频率下的GW探测需要时间，并且有必要使用最先进的数据分析技术来为单个脉冲星数据集建立定制的噪声模型，以便在PTA进入探测时代之际增加NSF在纳赫兹引力波天文学方面的巨大投资。随着随机GWB的宇宙交响乐在数据中变得更加重要，PTA现在有必要调整这些星系尺度的探测器，以优化同时解析单个SMBHs的能力。PTAS将对活动星系核中准周期光曲线的SMBBH假设进行仲裁，这项工作将通过通知PTA和LSST观测策略来最大化SMBBH系统的多源探测空间，以确保在LSST时代探测到多源。该项目包括以天体物理学为主题的数据分析暑期研讨会的课程开发和实施，该研讨会将促进灵感教学，激发对PTA研究的兴奋，促进本科生和研究生的学习目标，并支持社区大学学生过渡到四年制学校。第一个研究目标将是使用最近开创的技术，通过使用定制贝叶斯模型来转换PTA噪音缓解策略，以从我们手中已有的数据中获得信息。初步分析表明，在使用这些定制模型时，参数恢复和显著性统计发生了显著变化。这项工作将有助于重新构思使用探测器表征工具来重新思考脉冲星观测战略，并对这些工具进行重组，以便从电磁时间域调查中轻量级地预测GW候选者的单源可探测性。在前两个目标的支持下，将研究开发快速评估AGN是否存在SMBBH所需的框架和软件接口。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The recent announcement by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and pulsar timing array (PTA) collaborations around the world of evidence for a gravitational wave background (GWB) demonstrates that PTAs are moving into an unprecedented sensitivity regime for gravitational wave (GW) signals in the nanohertz frequency range. PTAs can see further back in time than the cosmic microwave background radiation and allow us to survey the population of supermassive binary black holes (SMBBHs) as a stochastic GWB. Detection of the background heralds the coming of individual source detections just when the Vera C. Rubin Observatory and the ten-year Legacy Survey of Space and Time (LSST) are scheduled to begin obtaining consistent and high quality time series data of active galactic nuclei (AGN) --- perfectly timed to coincide with the era of the first single-source detections in the PTA band. GW detections at these frequencies take time and necessitate the use of state-of-the-art data analysis techniques to build custom noise models for individual pulsar data sets in order to enhance the huge investment of the NSF into nanohertz gravitational wave astronomy just as PTAs enter the detection era. As the cosmic symphony of the stochastic GWB becomes more significant in the data, it is now necessary for PTAs to tune these galactic-scale detectors to optimize the ability to also resolve individual SMBBHs. PTAs will arbitrate the SMBBH hypothesis for quasiperiodic light curves in AGN, and this work will maximize the multimessenger detectability space of SMBBH systems by informing PTA and LSST observing strategies in order to ensure the detection of a multimessenger source during the LSST-era. The project includes curriculum development and implementation of a summer workshop in astrophysics-themed data analysis that will foster inspired teaching, stimulate excitement in PTA research, facilitate the learning goals of undergraduate and graduate students, and support the transition of community college students into 4-year schools. The first research goal will be using techniques recently pioneered to transform PTA noise mitigation strategies with the use of custom Bayesian models to gain from the data we already have in hand. Preliminary analyses have shown significant changes in parameter recovery and significance statistics when using these custom models. This work will inform a reconceptualization of the use of detector characterization tools to rethink pulsar observing strategies and the reorganization of these tools for lightweight predictions of single-source detectability of GW candidates from electromagnetic time-domain surveys. Supported by these first two goals will be research to develop the framework and software interface needed to quickly assess AGN for the presence of SMBBHs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.