双星系统中中子星的初始 kick 速度
The Kick Velocities of Neutron Stars in Binary Systems
浏览论文内容
中文总结 AI 辅助
本研究通过 COMPAS 种群合成代码，结合 Gaia 等多类双星观测，发现大质量伴星双星中的中子星初始 kick 显著降低，可解释多数观测结果。
中文摘要 AI 辅助
中子星（NS）在超新星（SNe）形成时会获得初始 kick 速度。我们研究不同类型双星系统中的中子星对初始 kick 速度大小施加的约束，将观测到的系统与 COMPAS 快速种群合成代码的预测结果进行比较，其中我们应用具有不同初始 kick 规则的 kick 模型。具体而言，我们比较了以下五类系统的双星轨道（即周期和偏心率）及系统级 kick 估计：1. 盖亚（Gaia）观测的含中子星的双星（Gaia NSs）；2. 中子星低质量 X 射线双星（LMXBs）；3. 中子星-白矮星双星（NSWDs）；4. 中子星高质量 X 射线双星（HMXBs），尤其是 Be X 射线双星（BeXBs）；5. 双中子星（DNSs）。在该比较中，我们发现，将初始 kick 校准到年轻孤立脉冲星的速度，可重现 Gaia NSs、LMXBs 和 NSWDs 的大部分观测性质，尽管我们需要“火箭” kick 来解释 Gaia NS 的偏心率。相比之下，HMXBs 和 DNSs 显示出中子星初始 kick 显著降低的证据。我们特别发现，如果初始 kick 小于等于 10 km/s，DNSs 的偏心率与系统级 kick 之间的明显相关性可通过 Blaauw kick 解释。尽管我们的模型与低金属丰度 Gaia NSs、高偏心率 BeXBs 和 DNS 质量估计的契合度不佳，但我们为这些系统提供了替代假设解释。我们得出结论，与大质量伴星形成于双星系统中的中子星会获得显著降低的初始 kick，该模型可相对一致地解释观测到的双星系统中的中子星。
英文摘要
Neutron stars (NSs) receive natal kicks on their formation in supernovae (SNe). We consider constraints placed on the natal kick magnitudes by NSs in different classes of binary systems. We compare observed systems to predictions from the COMPAS rapid population synthesis code, where we apply kick models with varied natal kick prescriptions. Specifically, we compare binary orbits (i.e., periods and eccentricities) and systemic kick estimates of (1) Gaia observations of NS-harboring binaries (Gaia NSs), (2) NS low-mass X-ray binaries (LMXBs), (3) NS-white dwarf binaries (NSWDs), (4) NS high-mass X-ray binaries (HMXBs) and in particular Be X-ray binaries (BeXBs), and (5) double NSs (DNSs). In this comparison, we find that we can reproduce most of the observed properties of the Gaia NSs, LMXBs, and NSWDs with natal kicks calibrated to the velocities of young isolated pulsars, although we need a small amount of "rocket" kicks to explain the Gaia NS eccentricities. The HMXBs and DNSs, in contrast, show evidence of significantly reduced NS natal kicks. In particular, we find that an apparent correlation between eccentricity and systemic kick for DNSs can be explained by Blaauw kicks, if the natal kicks are $\lesssim 10$ km s$^{-1}$. Although our model does not align well with low-metallicity Gaia NSs, high-eccentricity BeXBs, and DNS mass estimates, we provide alternative hypothetical explanations for these systems. We conclude that a model in which NSs that are formed in binaries with high-mass companions receive significantly reduced natal kicks can provide a relatively consistent explanation for the observed NSs in binary systems.
