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

最近，北美纳赫兹引力波天文台（nanogravity）和脉冲星定时阵列（PTA）在全球范围内合作发现了引力波背景（GWB）的证据，这表明，PTAs对纳赫兹频率范围内的引力波（GW）信号的灵敏度正在达到前所未有的水平。PTAs可以比宇宙微波背景辐射看到更早的时间，并允许我们将超大质量双黑洞（SMBBHs）的数量作为随机GWB进行调查。背景探测预示着单个源探测的到来，就在Vera C. Rubin天文台和十年的时空遗产调查（LSST）计划开始获得活动星系核（AGN）的一致和高质量的时间序列数据时——完美地与PTA波段第一次单源探测的时代相吻合。在这些频率上进行GW探测需要时间，并且需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PTAs进入探测时代之际，增加NSF对纳赫兹引力波天文学的巨大投资。随着随机GWB的宇宙交响乐在数据中变得越来越重要，PTAs现在有必要调整这些星系尺度探测器，以优化解析单个smbbh的能力。PTA将对AGN准周期光曲线的SMBBH假设进行仲裁，该工作将通过告知PTA和LSST观测策略来最大化SMBBH系统的多信使可探测空间，以确保在LSST时代检测到多信使源。该项目包括课程开发和天体物理学主题数据分析暑期研讨会的实施，这将促进启发性教学，激发PTA研究的激情，促进本科生和研究生的学习目标，并支持社区大学学生向四年制学校的过渡。第一个研究目标将是使用最近首创的技术，通过使用自定义贝叶斯模型来转换PTA噪声缓解策略，以从我们已经掌握的数据中获益。初步分析表明，在使用这些自定义模型时，参数恢复和显著性统计数据发生了显著变化。这项工作将重新定义探测器表征工具的使用，以重新思考脉冲星观测策略，并重组这些工具，以便从电磁时域调查中对GW候选天体的单源可探测性进行轻量级预测。在前两个目标的支持下，将研究开发框架和软件接口，以快速评估smbbh存在的AGN。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.