Dynamical Tides in White Dwarf Binaries: Theory and Applications

像太阳这样的恒星的最后阶段是一颗被称为白矮星（WD）的致密恒星。白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依靠余热发光。康奈尔大学的一个研究小组将研究与另一个天体物理物体在双星系统中的WDs。这些双星系统可以导致奇异物体的形成（如Ia型超新星或潮汐破坏事件），它们是低频（mHz）引力波（GWs）的重要来源，将被未来的激光干涉仪空间天线（LISA）探测到。该项目将试图了解潮汐耗散在WD中的物理特性，潮汐耗散对WD结构和演变的影响，以及潮汐如何影响GW发射和探测。结果的可视化（例如重力波破裂及其与海浪和冲浪的联系）将在网上发布，用于教育目的。该计划将为研究生提供支持，他们将接受许多多学科领域和科学计算方面的培训。首席研究员将继续吸引有才华的本科生参与研究。研究团队将对双WDs中非线性内部重力波破断潮汐耗散进行数值模拟（目的是确定WDs中的潮汐加热剖面），研究合并前WDs的热演化，量化潮汐效应对光发射和mHz GW信号的影响。研究小组还将研究高偏心的WD- mbh双星在WD潮汐破坏之前的长期演化。考虑到引力辐射和黑洞旋转的影响，他们将研究由于围绕黑洞的重复中心通道导致的黑洞振荡模式（“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双星的mHz GW发射的影响。紧凑的WD双星是LISA的重要GW辐射源。LISA从WD二进制文件中检测GWs依赖于匹配滤波，其中模板波形库与仪器数据匹配。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LISA探测管道的重力波形。这个项目推进了NSF宇宙大构想窗口的目标。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 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.