Collaborative Research: Optimized frequency-domain analysis for astronomical time series

类地行星搜索正在进行中，它可以测量遥远恒星周围小行星的运动。但是，如果没有计算机软件的进步，对这些工具的投资将无法充分发挥其潜力。通过一项为期三年的奖励，特拉华大学和芝加哥大学领导的一个团队将把以前用于健康科学和太阳科学的时域数据分析工具用于天文学。开发新的分析方法将通过减少观测次数和提高望远镜效率，节省每晚花费数万美元的望远镜时间。学生将参与行星搜索。该团队的目标是让物理学和天文学专业的学生参与到行星搜索的各个层次的学术准备中，并创造一个支持性的环境，让学生可以从教师、学者和其他人那里寻求帮助。虽然Lomb-Scargle周期图是天文学的基础，但它有一个明显的缺点：它的方差不会随着获得更多数据而减小。统计学家开发抑制方差的功率谱估计器已有60年的历史，但大多数都没有用于天文学，因为它们是为具有统一观测节奏的时间序列而制定的，没有季节或每日的差距。该团队将通过对地面天文时间序列采用多锥度功率谱估计器来减轻Lomb-Scargle周期图的假阳性和偏置问题。他们将提出多锥度幅度平方相干（MSC）作为在两个或多个可观测值中共同表现的振荡的诊断。活动指标和径向速度之间的MSC是识别恒星旋转和谐波的有力工具，这是许多误报行星探测的原因。他们将为地基时间序列引入一种非多锥度版本的复杂解调。复杂解调是一种局部傅立叶分解，它重建了两个耦合振荡的长周期分量，可以区分活动调制的恒星信号和非调制的行星信号，并从脉动恒星的观测中恢复全相位旋转信号。该奖项资助了振荡识别和分类软件（ORCAS）软件包的开发，该软件包将包含我们的频域方法的python和Julia实现。ORCAS将持续托管在bitbucket上，并在天体物理源代码库中注册。所开发的方法可以应用于行星搜寻、地震学、古气候学、遗传学、激光多普勒测速和鲁宾天文台时空遗产调查。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。

Earth-like planet searches are underway which can measure the motion of small planets around distant stars. However, investments in these instruments will not meet their full potential without advances in computer software. Through a three year award, a team led by the Universities of Delaware and Chicago will adapt a time domain data analysis tool previously used for health science and solar science for astronomy. Developing new analysis methods will save telescope time that costs tens of thousands of dollars per night by reducing the number of observations needed and increasing telescope efficiency. Students will be involved in the planet searches. The Team's goals are to involve physics and astronomy majors with all levels of academic preparation in planet searches and to create a supportive environment in which students can seek help from a faculty, scholars, and each other. While the Lomb-Scargle periodogram is foundational to astronomy, it has a significant short-coming: its variance does not decrease as more data are acquired. Statisticians have a 60-year history of developing variance-suppressing power spectrum estimators, but most are not used in astronomy because they are formulated for time series with uniform observing cadence and without seasonal or daily gaps. The team will mitigate the false-positive and bias problems of the Lomb-Scargle periodogram by adapting the multitaper power spectrum estimator for ground-based astronomical time series. They will present multitaper Magnitude-Squared Coherence (MSC) as a diagnostic of oscillations that manifest jointly in two or more observables. MSC between activity indicators and radial velocity is a powerful tool for identifying stellar rotation and harmonics, which have been responsible for many false positive planet detections. They will introduce a non-multitaper version of complex demodulation for ground-based time series. Complex demodulation, a local Fourier decomposition that reconstructs the long-period component of two coupled oscillations, can distinguish activity-modulated stellar signals from non-modulated planetary signals and recover full-phase rotation signals from observations of pulsating stars. This award funds development of the Oscillation Recognition and CAtegorization Software (ORCAS) package, which will contain python and Julia implementations of our frequency-domain methods. ORCAS will be sustainably hosted on bitbucket and registered with the Astrophysical Source Code Library. The methods developed can be applied to planet hunting, seismology, paleoclimatology, genetics, laser Doppler velocimetry, and the Rubin Observatory Legacy Survey of Space and Time.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.