It is difficult for the intermediate-mass X-ray binaries (IMXBs) evolutionary channel to form intermediate-mass binary pulsars (IMBPs) with a short orbital period (less than 3 d) via stable mass transfer. The main reason is that the magnetic braking mechanisms are generally thought not to work for donor stars with a mass of greater than 1.5 $\rm M_{\odot}$ in the canonical model. However, some intermediate-mass stars have anomalously strong magnetic fields (about 100 -- 10000 G), i. e. so-called Ap or Bp stars. With the coupling between the magnetic field and the irradiation-driven wind from the surface of Ap/Bp stars, a plausible magnetic braking mechanism should be expected. In this work, we attempt to investigate if IMXBs with Ap/Bp stars can produce IMBPs with a short orbital period (less than 3 d) by such an anomalous magnetic braking mechanism. Using a stellar evolution code, we have simulated the evolution of a large number of IMXBs consisting of a NS and an Ap/Bp star. For the spin evolution of the NS, we consider the accretion torque, the propeller torque, and the spin-down torque caused by the interaction between the magnetic field and the accretion disc. The calculated results show that, employing anomalous magnetic braking of Ap/Bp stars, IMXBs can evolve into compact IMBPs with short orbital periods of less than 3 d. However, there exists significant discrepancy between the spin periods of IMBPs in our simulated results and those observed.
The braking index of PSR J1734-3333 and the magnetar population
PSR J1734-3333是一颗射电脉冲星，其自转周期为P=1.17 s，减速周期导数为Pdot=2.28 x 10^{-12}，在自转脉冲星中排名第三。这些性质介于正常旋转动力中子星和磁星之间，这两种中子星的辐射性质明显不同。在这里，我们报告的PSR J1734-3333的旋转的第二周期导数的测量和计算的制动指数n=0.9 +-0.2。这个值远低于3，即恒定磁偶极子电磁制动的预期值，表明该脉冲星可能很快具有磁星的旋转特性。虽然有几种机制可能导致如此低的制动指数，我们讨论了这一观察结果，以及其他一些高Pdot旋转动力的磁星所表现出的特性，并将其解释为磁星通过无线电脉冲星阶段的可能进化路线的证据，支持这两类物体的统一描述。
The evolutions of a neutron star's rotation and magnetic field (B-field) have remained unsolved puzzles for over half a century. We ascribe the rotational braking torques of pulsar to both components, the standard magnetic dipole radiation (MDR) and particle wind flow ( MDR + Wind, hereafter named MDRW), which we apply to the Crab pulsar (B0531 + 21), the only source with a known age and long-term continuous monitoring by radio telescope. Based on the above presumed simple spin-down torques, we obtain the exact analytic solution on the rotation evolution of the Crab pulsar, together with the r…
Black widows are millisecond pulsars with low-mass companions, a few per cent the mass of the sun, on orbits of several hours. These companions are presumably the remnants of main sequence stars that lost their mass through a combination of Roche-lobe overflow and ablation by the host pulsar's high-energy radiation. While ablation itself is too weak to significantly reduce the mass of the companion star, the ablated wind couples to its magnetic field, removes orbital angular momentum, and thus maintains stable Roche-lobe overflow. We use the MESA stellar evolution code, complemented by analyti…
Extremely low-mass white dwarfs (ELM WDs) are the result of binary evolution in which a low-mass donor star is stripped by its companion leaving behind a helium-core white dwarf. We explore the formation of ELM WDs in binary systems considering the Convection And Rotation Boosted magnetic braking treatment. Our evolutionary sequences were calculated using the MESA code, with initial masses of 1.0 and 1.2 Msun (donor), and 1.4 (accretor), compatible with low mass X-ray binaries (LMXB) systems. We obtain ELM models in the range 0.15 to 0.27 Msun from a broad range of initial orbital periods, 1 t…
PSR J0537$-$6910 is the most active glitching pulsar with a glitch rate $\sim0.3$ yr $^{-1}$. We have reanalysed 45 glitches of PSR J0537$-$6910 published in the literature and have done post-glitch timing fits within the vortex creep model. Moment of inertia fractions of the superfluid regions participating in glitches are obtained for each event and the model predictions for the inter-glitch time are confronted with the observed time-scales. Similarities and differences with the glitching behaviours of the well studied Crab and Vela pulsars are highlighted. From superfluid recoupling time-sc…
Modeling the evolution and distribution of the frequency's second derivative and the braking index of pulsar spin
我们模拟的自旋频率的二阶导数$\ddotν$和制动指数$n$的射电天体的表面磁场演化的唯象模型内的模拟，其中包含一个长期的幂律衰减调制的短期振荡的演变。对于脉冲星PSR B 0329 +54，一个包含三个振荡分量的模型可以再现其$\ddotν$变化。我们发现，“平均”的$n$是不同的瞬时$n$，其振荡幅度急剧下降的时间跨度的增加，由于“平均”的效果。模拟的时序残差与报道数据的主要特征一致。我们的模型预测，PSR B 0329 +54的平均$\ddotν$将开始快速下降，更新数据超出Hobbs等人使用的数据。我们进一步进行蒙特卡罗模拟$|\ddotν|$和$|n|$与特征年龄$τ_{\rm c}$图中报告数据的分布。结果表明，用衰减指数$α=0$建立的磁场振荡模型能很好地再现这些分布。与双极扩散（$α=0.5$）和霍尔级联（$α=1.0$）引起的磁场衰减相比，通过二维Kolmogorov-Smirnov检验的p值，无长期衰减的模型（$α=0$）显然更适合于旧的磁体。
Evolution of cataclysmic variables under different magnetic braking prescriptions
School of Physical Science and Technology, Xinjiang University（新疆大学物理科学与技术学院）；Department of Nuclear Physics and Astronomy, Institute of Engineering Physics, Samarkand State University（撒马尔罕国立大学工程物理学院核物理与天文学系）
Close-orbit low-mass X-ray binaries (LMXBs), radio binary millisecond pulsars (BMSPs) with extremely low-mass helium WDs (ELM He~WDs) and ultra-compact X-ray binaries (UCXBs) are all part of the same evolutionary sequence. It is therefore of uttermost importance to understand how these populations evolve from one specie to another. Moreover, UCXBs are important gravitational wave (GW) sources and can be detected by future space-borne GW observatories. However, the formation and evolutionary link between these three different populations of neutron star (NS) binaries are not fully understood. I…
On the connection between accreting X-ray and radio millisecond pulsars
多年来，人们已经认识到，在低质量X射线双星（LMXB）的质量转移的终端阶段应该导致吸积中子星的磁层膨胀，导致制动扭矩作用于旋转的脉冲星。因此，在发现射电毫秒双星（MSP）之后，这些双星如何在罗氏瓣退耦阶段（RLDP）之后保持其快速自旋就成了一个悖论（例如Ruderman et al. 1989）。在这里，我提出了一个解决这个所谓的“关断问题”，这是最近发现的结合二进制恒星演化模型与扭矩计算（陶里斯2012）。解决的办法是，在RLDP期间，脉冲星的自旋平衡被打破，因此它仍然是一个快速旋转的物体。我简要地讨论了这些发现，鉴于两个观察到的自旋分布在人口的吸积X射线毫秒双星（AXMSP）和无线电MSP。
