Predictive monitoring of aperiodic sources

非周期源的预测性监测

• 批准号: 1815034
• 负责人: Matthew Graham
• 金额: $ 29.99万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1815034&HistoricalAwards=false
• 关键词: Predictive; monitoring; aperiodic; sources

Many studies of objects in the sky that vary in brightness look only at periodic variation, with a regular and repeating change with time. However, most variable astronomical sources are aperiodic, showing erratic and irregular changes. They remain poorly studied in comparison to periodic sources, even though they can play a key role in our understanding of complex dynamic physical environments, from stars, to gas and dust flows, to galaxies. This work studies aperiodic variability using the data from two NSF-supported projects, the Catalina Real-time Transient Survey (CRTS), and the newly begun Zwicky Transient Facility (ZTF). This is the first large-scale systematic study of these phenomena, and it will be the definitive study, well into the next decade. It is an excellent case study for data-intensive science, applying state-of-the-art machine learning techniques to real data. It will expose students to cutting-edge data science, and its products will contribute to projects that will train the next generation in how to handle big astronomical data.Even though the majority of variable sources are aperiodic, they are poorly understood, and for well-known examples like quasars and young stellar objects many fundamental questions remain about the physical mechanisms behind their optical variability. New sky surveys are enabling systematic studies of variability and discovering many new phenomena, including sub-parsec separated quasar binaries, multi-year long flares attributable to microlensing of explosive activity in the accretion disk, and changing-state sources indicative of variable accretion rates. These extreme behaviors should be easily discoverable with modern robust statistical methods. This work will create generative data-derived models with novel non-parametric discriminating features from CRTS data, and use the models to predict the future behavior of aperiodic sources, which can then be monitored in real-time using ZTF and other synoptic facilities. Prior work focused on robust statistical characterization and identifying extreme variable classes. This will be extended to more general aperiodic sources and more sophisticated non-parametric generative models. The unprecedented sky coverage of ZTF joins with the unequalled archival coverage of CRTS to make this the definitive study. In keeping with the CRTS Open Data and ZTF alert policies, all transitioning objects identified will be released to the community.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.

许多对天空中亮度变化的物体的研究只关注周期性变化，即随着时间的推移而发生规律性和重复性的变化。 然而，大多数可变的天文源是非周期性的，表现出不稳定和不规则的变化。 与周期源相比，它们仍然缺乏研究，尽管它们在我们理解复杂的动态物理环境中发挥着关键作用，从恒星到气体和尘埃流，再到星系。 这项工作研究非周期性的变化，使用的数据从两个NSF支持的项目，卡塔利纳实时瞬态调查（CRTS），和新开始的Zwicky瞬态设施（ZTF）。 这是对这些现象的第一次大规模系统研究，它将是下一个十年的决定性研究。 这是数据密集型科学的一个很好的案例研究，将最先进的机器学习技术应用于真实的数据。 它将让学生接触到最前沿的数据科学，其产品将有助于培养下一代如何处理大天文数据的项目。尽管大多数可变源都是非周期性的，但人们对它们的了解却很少，对于类星体和年轻恒星物体等众所周知的例子，许多关于其光学可变性背后的物理机制的基本问题仍然存在。 新的巡天观测使人们能够系统地研究变率，并发现许多新现象，包括亚秒差距分离的类星体双星、可归因于吸积盘中爆炸活动微透镜的多年长耀斑，以及表明可变吸积率的变化状态源。 这些极端行为应该很容易用现代强大的统计方法来解释。 这项工作将创建具有CRTS数据的新型非参数判别特征的生成数据衍生模型，并使用这些模型来预测非周期源的未来行为，然后可以使用ZTF和其他天气设施进行实时监测。 以前的工作集中在强大的统计特性和识别极端变量类。 这将扩展到更一般的非周期源和更复杂的非参数生成模型。 ZTF前所未有的天空覆盖率与CRTS无与伦比的档案覆盖率相结合，使其成为权威性的研究。 根据CRTS开放数据和ZTF警报政策，所有确定的过渡对象将向社区发布。该奖项反映了NSF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。

项目成果

Deep Modeling of Quasar Variability

• DOI: 10.3847/1538-4357/abb9a9
• 发表时间: 2020-03
• 期刊: The Astrophysical Journal
• 作者: Yutaro 朗橘 Tachibana 優太;M. Graham;N. Kawai;S. Djorgovski;A. Drake;A. Mahabal;D. Stern

The first high-redshift changing-look quasars

• DOI: 10.1093/mnras/staa2415
• 发表时间: 2019-12
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: N. Ross;M. Graham;G. Calderone;K. Ford;K. Ford;B. McKernan;B. McKernan;D. Stern