标题： 从激波膨胀伴星的吸积：将中子星自转减速到小时量级周期 显示英文标题

标题： Accretion from a Shock-Inflated Companion: Spinning Down Neutron Stars to Hour-Long Periods

摘要： 最近的观测揭示了一类自转周期为几分钟到几小时的脉冲星，它们位于传统的“死亡线”之外。 如果它们起源于中子星（NSs），这种超长周期脉冲星（ULPs）的存在挑战了我们对NS演化的当前理解。 在本研究中，我们提出了一种新的盘形成渠道，基于在密近双星系统中诞生的中子星，其伴星为主序星。 通过超新星-伴星相互作用的流体动力学模拟，我们表明，新生的中子星在穿过由爆炸形成的复杂密度场时可能会引力捕获气体。 对于双星分离度为$20\rm~R_\odot$以及伴星质量为$4\rm~M_\odot$的情况，我们发现围绕未束缚中子星形成盘的发生率为$\sim10\%$。 通过建模盘的演化及其与中子星的相互作用，我们发现自转周期存在双峰分布：具有$P\lesssim10\rm\,s$的常规脉冲星是那些缺乏盘或其磁层从未与盘相互作用的脉冲星，而具有$10^3\lesssim P<10^5\rm\,s$的ULPs是在系统经历短暂的“螺旋桨”阶段期间中子星快速自转减速时产生的。 这种ULPs是在强初始偶极磁场强度$B_0\gtrsim10^{14}\rm\,G$下形成的，在银河系中的形成速率为$10^{-4}\rm\,yr^{-1}$。 我们还发现，一些脉冲星种群具有中等磁场强度（$10^{13}\lesssim~B_0\lesssim10^{14}\rm\,G$）和相对较慢的初始周期（$P_0\gtrsim0.1\rm\,s$），它们会演化到$P\sim10^2\rm\,s$，填补双峰分布之间的空缺。因此，我们的模型为超出“死亡线”的脉冲星提供了一个统一的解释。 显示英文摘要

摘要： Recent observations have unveiled a population of pulsars with spin periods of a few minutes to hours that lie beyond the traditional ``death line.'' If they originate from neutron stars (NSs), the existence of such ultra-long period pulsars (ULPs) challenges our current understanding of NS evolution and emission. In this work, we propose a new channel for disk formation based on NSs born in close binaries with main-sequence companion stars. Using a hydrodynamic simulation of supernova-companion interactions, we show that a newborn NS may gravitationally capture gas as it moves through the complex density field shaped by the explosion. For a binary separation of $20\rm~R_\odot$ and a companion mass of $4\rm~M_\odot$, we find the occurrence fraction for disk formation around unbound NSs to be $\sim10\%$. By modeling the disk evolution and its interaction with the NS, we find a bimodal distribution in spin periods: canonical pulsars with $P\lesssim10\rm\,s$ are the ones who lack disks or whose magnetospheres never interacted with the disk, and ULPs with $10^3\lesssim P<10^5\rm\,s$ are produced when the system undergoes a short-lived ``propeller'' phase during which the NS undergoes rapid spin-down. Such ULPs are formed under strong initial dipolar magnetic field strengths $B_0\gtrsim10^{14}\rm\,G$, with a formation rate of $10^{-4}\rm\,yr^{-1}$ in the Milky Way. We also find that a small population of pulsars with moderate magnetic field strengths ($10^{13}\lesssim~B_0\lesssim10^{14}\rm\,G$) and relatively slow initial periods ($P_0\gtrsim0.1\rm\,s$) evolve to $P\sim10^2\rm\,s$, filling the gap between the bimodal distribution. Thus, our model provides a unified explanation for pulsars beyond the ``death line.''