The First Multi-Messenger Study of Supermassive Black Hole Growth

约瑟夫·西蒙被授予美国国家科学基金会天文学和天体物理学奖学金，以在科罗拉多大学开展一项研究和教育计划。结合引力波(GW)背景的脉冲星定时阵列(PTA)测量和星系合并的电磁观测，Simon将模拟黑洞(BH)如何合并形成超大质量黑洞(SMBH)。该项目的结果将使天文学家更好地了解SMBH质量增长的原因。西蒙还将为本科生提供研究指导，并让他们参与到当地初中和高中的外展活动中，这些学校服务于资源丰富的社区。PTA数据中出现的GW背景的暗示似乎与忽略BH-BH合并的贡献的理论预测不一致，并暗示SMBH比之前认为的更大，或更频繁地合并。在这个项目中，西蒙将把对星系合并和SMBH质量函数的最佳可用观测，以及对双星演化时间尺度的新规定，纳入他对双星SMBH群体和GW背景的建模框架中。他将首先使用他的改进模型从PTA数据中提取双星演化时间尺度。然后，他将把星系合并的电磁观测和SMBH质量函数与PTA观测结合起来，首次对由于BH-BH合并而导致的SMBH质量增长进行多信使测量。这个项目推进了NSF宇宙大理想之窗的目标。这一奖项反映了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。

Joseph Simon is awarded an NSF Astronomy and Astrophysics Fellowship to carry out a program of research and education at the University of Colorado. Combining pulsar timing array (PTA) measurements of the gravitational wave (GW) background with electromagnetic observations of galaxy mergers, Simon will model how black holes (BH) merge to form supermassive black holes (SMBH). Results from this project will allow astronomers to better understand how SMBH grow in mass. Simon will also provide research mentoring to undergraduate students and engage them in a program of outreach activities to local middle schools and high schools serving under resourced communities. Hints of the GW background emerging in PTA data appear inconsistent with theoretical predictions neglecting the contributions from BH-BH mergers and imply that SMBHs are more massive, or merge more frequently than previously thought. In this project, Simon will incorporate the best available observations of galaxy mergers and the SMBH mass function alongside a new prescription for the binary evolution timescale into his modeling framework for the binary SMBH population and the GW background. He will first use his refined models to extract the binary evolution timescale from PTA data. He will then combine the electromagnetic observations of galaxy mergers and the SMBH mass function with PTA observations to conduct the first multi-messenger measurement of SMBH mass growth due to BH-BH mergers. This project advances the goals of the NSF Windows on the Universe Big Idea.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.