AI 中文总结
研究人员开发了基于Kadath库的Celephais代码，可构建无赤道对称性约束的致密双星初始数据，通过自适应hp细化等技术提升效率，经测试能以更少未知量实现高精度，支持任意自旋取向的初始数据构建。
AI 中文摘要
大规模数值相对论巡天需要兼具谱精度且构建成本低廉的致密双星初始数据，包括质量不等且自旋错位的系统。我们提出Celephais，这是一款基于Kadath谱库构建的致密天体初始数据代码，可构建无赤道对称性约束的双中子星及黑洞-中子星初始数据。该方法利用全局耦合多域雅可比矩阵的稀疏结构与场的近似宇称分离特性，组装后的矩阵用MUMPS分解，并作为更新的右预条件子在无雅可比牛顿-克雷夫特迭代中重复使用，从而避免密集存储。自适应hp细化方案随后在谱尾未解析的区域集中分辨率。对于质量比20的黑洞-中子星基准测试，自适应方案以约三分之一的未知量恢复了均匀网格的约束精度。我们还将后牛顿力平衡估计扩展到任意自旋取向，并用于初始化偏心率缩减。验证包括与后牛顿序列的结合能比较、进动双中子星的偏心率缩减测试，以及其波形重建的进动轴符合后牛顿简单进动模型的完整演化。这些结果为获取具有任意自旋取向的谱解析双中子星及黑洞-中子星初始数据建立了高效途径。
英文摘要
Large numerical-relativity surveys require compact-binary initial data that are both spectrally accurate and inexpensive to construct, including for systems with unequal masses and misaligned spins. We present \celephais, a compact-object initial-data code built on the \texttt{Kadath} spectral library, that constructs binary-neutron-star and black-hole--neutron-star initial data without imposing equatorial symmetry. The method exploits the sparse structure of the globally coupled multi-domain Jacobian and the approximate parity separation of fields. The assembled matrix is factored with \texttt{MUMPS} and reused as a refreshed right preconditioner in a Jacobian-free Newton--Krylov iteration, thereby avoiding dense storage. An adaptive $hp$--refinement scheme then concentrates resolution where the spectral tails are not yet resolved. For a mass-ratio-$20$ black-hole--neutron-star benchmark, the adaptive schemes recover the uniform-grid constraint accuracy with about three times fewer unknowns. We also extend the post-Newtonian force-balance estimate to arbitrary spin orientations and use it to initialise eccentricity reduction. Validation comprises binding-energy comparisons with post-Newtonian sequences, a precessing binary-neutron-star eccentricity-reduction test, and a full evolution whose waveform-reconstructed precession axis follows a post-Newtonian simple-precession model. These results establish an efficient route to spectrally resolved binary-neutron-star and black-hole--neutron-star initial data with arbitrary spin orientations.
Comments16 pages, 10 figures, 2 tables. Comments welcome!
