Dynamical Tides in White Dwarf Binaries: Theory and Applications

像太阳这样的星星的末期是一颗紧凑的星星，称为白色矮星（WD）。一颗白色矮星不再通过核聚变产生能量，而是会在数十亿年的时间里从余热中发光。康奈尔大学的一个研究小组将研究与另一个天体物理学物体处于双星系统中的WD。这些双星系统可以导致奇异天体的形成（如Ia型超新星或潮汐破裂事件），它们是未来激光干涉仪空间天线（丽莎）探测低频（mHz）引力波（GW）的重要来源。该计划将寻求了解WD中潮汐耗散的物理学，潮汐耗散对WD结构和演变的影响，以及潮汐如何影响GW的排放和检测。结果的可视化（如重力波破碎及其与海浪和冲浪的联系）将在网上公布，用于教育目的。该计划将为研究生提供支持，他们将在许多多学科领域和科学计算方面接受培训。首席研究员将继续让有才华的本科生参与研究。研究小组将通过二元WD中的非线性内部重力波破碎进行潮汐耗散的数值模拟（目的是确定WD中的潮汐加热剖面），研究合并前的WD热演化，并量化潮汐效应如何影响光发射和mHz GW信号。该小组还将研究在WD潮汐破坏之前高度偏心的WD-MBH双星的长期演化。他们将研究由于MBH周围的重复近心通道，考虑到引力辐射和WD旋转的影响，WD振荡模式（“混沌潮汐”）的混沌增长。研究人员将探索这些模式的线性和非线性阻尼，并研究它们对WD演化和WD-MBH二进制的mHz GW发射的影响。紧凑WD双星是丽莎的重要GW辐射源。通过丽莎从WD二进制中检测GW依赖于匹配滤波，其中模板波形库与仪器数据相匹配。因此，模板库的准确性和完整性至关重要。科学家们将使用他们的潮汐双星WD演化模型来计算用于丽莎探测管道的重力波形。该项目推进了NSF宇宙大创意窗口的目标。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。

The end stage of a star like the Sun is a compact star called a white dwarf (WD). A white dwarf no longer produces energy by nuclear fusion, but will glow from residual heat for billions of years. A research team at Cornell University will study WDs that are in a binary system with another astrophysical object. These binary systems can lead to the formation of exotic objects (such as Type Ia supernovae or tidal disruption events), and they are important sources of low-frequency (mHz) gravitational waves (GWs) to be detected by the future Laser Interferometer Space Antenna (LISA). This program will seek to understand the physics of tidal dissipation in the WD, the effect of tidal dissipation on the WD structure and evolution, and how tides affect the GW emission and detection. Visualizations of the results (such as gravity wave breaking and its connection to ocean waves and surfing) will be published on the web for educational purposes. This program will provide support for graduate students, who will receive training in many of the multidisciplinary areas, and in scientific computing. The lead investigator will continue to engage talented undergraduate students in research. The research team will carry out numerical simulations of tidal dissipation via nonlinear internal gravity wave breaking in binary WDs (with the goal of determining the tidal heating profile in the WD), study WD thermal evolution prior to merger, and quantify how tidal effects influence the optical emission and mHz GW signals. The team will also study the long-term evolution of highly eccentric WD-MBH binaries prior to tidal disruption of the WD. They will examine the chaotic growth of WD oscillation modes (“chaotic tides”) due to repeated pericenter passages around the MBH, taking account of the effect of gravitational radiation and WD rotation. The researchers will explore the linear and nonlinear dampings of these modes and study their effects on the WD evolution and mHz GW emission from the WD-MBH binaries. Compact WD binaries are an important source of GW radiation for LISA. The detection of GWs from WD binaries by LISA relies on matched filtering, where a library of template waveforms is matched against instrument data. As such, the accuracy and completeness of the template library is of utmost importance. The scientists will use their tidal binary WD evolution model to compute gravitational waveforms for use in the LISA detection pipeline. 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.