Chua Alvin J K, Katz Michael L, Warburton Niels, Hughes Scott A
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.
Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.
Phys Rev Lett. 2021 Feb 5;126(5):051102. doi: 10.1103/PhysRevLett.126.051102.
The future space mission LISA will observe a wealth of gravitational-wave sources at millihertz frequencies. Of these, the extreme-mass-ratio inspirals of compact objects into massive black holes are the only sources that combine the challenges of strong-field complexity with that of long-lived signals. Such signals are found and characterized by comparing them against a large number of accurate waveform templates during data analysis, but the rapid generation of templates is hindered by computing the ∼10^{3}-10^{5} harmonic modes in a fully relativistic waveform. We use order-reduction and deep-learning techniques to derive a global fit for the ≈4000 modes in the special case of an eccentric Schwarzschild orbit, and implement the fit in a complete waveform framework with hardware acceleration. Our high-fidelity waveforms can be generated in under 1 s, and achieve a mismatch of ≲5×10^{-4} against reference waveforms that take ≳10^{4} times longer. This marks the first time that analysis-length waveforms with full harmonic content can be produced on timescales useful for direct implementation in LISA analysis algorithms.
未来的空间任务“激光干涉空间天线”（LISA）将在毫赫兹频率下观测到大量引力波源。其中，致密天体向大质量黑洞的极端质量比吸积是唯一将强场复杂性挑战与长寿命信号挑战结合在一起的源。在数据分析过程中，通过将这些信号与大量精确的波形模板进行比较来发现并表征它们，但在完全相对论波形中计算约10³ - 10⁵个谐波模式会阻碍模板的快速生成。我们使用降阶和深度学习技术，在偏心史瓦西轨道的特殊情况下，对约4000个模式进行全局拟合，并在具有硬件加速的完整波形框架中实现该拟合。我们的高保真波形可在1秒内生成，与生成时间长约10⁴倍的参考波形相比，失配度小于5×10⁻⁴。这标志着首次能够在对LISA分析算法直接实施有用的时间尺度上产生具有完整谐波内容的分析长度波形。
