当恒星不再对齐：研究种群合成代码中双黑洞形成的不一致性
When the stars don't align: Investigating inconsistencies in binary black hole formation across population synthesis codes
- The University of Chicago（芝加哥大学）
- Adler Planetarium（阿德勒天文馆）
- Northwestern University（西北大学）
- University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）
- Carnegie Mellon University（卡内基梅隆大学）
- Université de Genève（日内瓦大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过COSMIC、METISSE、POSYDON三个BPS代码对比发现，相同初始双恒星在哈勃时间内形成的BBH合并体数量差异显著，仅1个双恒星在三代码中均形成BBH，且代码间预测BBH属性不一致，凸显需系统比较BPS技术。
AI中文摘要：
双恒星种群合成（BPS）代码是研究双恒星完整演化过程以及宇宙中大量观测到的天体物理现象的极为有用的工具。鉴于BPS在现代天体物理研究中的广泛应用，必须系统地比较BPS代码在计算效率、灵活性和物理真实性方面的表现，以评估其一致性和稳健性。在本研究中，我们使用三个现代代码执行BPS：快速代码COSMIC、集成在COSMIC中的混合代码METISSE，以及详细代码POSYDON，针对三个具有相同初始双恒星的单金属丰度种群，尽可能确保物理参数化选择的一致性。以合并双黑洞（BBHs）的最终种群为测试案例进行研究，我们发现三个代码在属性、形成路径和前身星方面存在显著差异。在初始的100万颗金属丰度为0.01 Z⊙的双恒星种群中，每个代码都会产生约5000至9000个在哈勃时间内合并的BBHs。然而，只有一个初始双恒星在所有三个代码中都成为BBH合并体，且不到14%的BBH前身星在两个代码中一致合并。在两个代码中成为BBH合并体的双恒星通常经历不同的演化路径，并产生不同的最终属性。简而言之，即使对于相同的初始双恒星系统，这些代码在预测BBH合并属性方面也不一致。我们的研究结果强调，需要对BPS技术进行系统比较，更深入地理解BPS代码之间的物理和计算差异，并谨慎过度解读任何BPS代码的结果。
英文摘要：
Binary population synthesis (BPS) codes are valuable tools for investigating the end-to-end lives of binary stars as well as a myriad of observed astrophysical phenomena. Many ``rapid" BPS codes rely on semi-analytical single-star evolutionary tracks and disjointed prescriptions for binary physics. Updated ``hybrid" or ``detailed" BPS codes incorporate improved methodologies, but at a steeper computational cost that may limit broad exploration of physical uncertainties. Given the widespread use of BPS in modern astrophysical research, it is imperative to systematically compare BPS codes across the spectrum of computational efficiency, flexibility, and physical realism to gauge their consistency and robustness. In this work, we perform BPS on three single-metallicity populations of identical initial binaries using three modern codes --- the rapid code $\texttt{COSMIC}$, the hybrid code $\texttt{METISSE}$ integrated into $\texttt{COSMIC}$, and the detailed code $\texttt{POSYDON}$ --- ensuring consistent physical parameterizations where possible. We find stark differences in the properties, formation pathways, and progenitors of binary black hole (BBH) merger populations across the three codes. In a population of one million binaries at $0.01 Z_\odot$, each code results in $\sim 5,000\mbox{--}9,000$ BBHs that merge within a Hubble time. However, $\lesssim 14\%$ of progenitors overlap between two codes, and only $\textit{one}$ initial binary becomes a BBH merger across all three codes. Identical progenitors often follow different evolutionary pathways in each code and result in inconsistent BBH properties. Our results highlight the need for a deeper understanding of physical and computational differences between BPS codes and caution against over-interpreting results from any individual BPS code.
