Reduced spin-down rate of PSR J0738–4042 explained as due to an asteroid disruption event

作     者：Yong-Bo Yu Yong-Feng Huang 

作者机构：Department of AstronomyNanjing UniversityNanjing 210046China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University)Ministry of EducationNanjing 2 1 0046China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2016年第16卷第5期

页      面：41-46页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0825[工学-航空宇航科学与技术] 0704[理学-天文学] 

基　　金：supported by the National Basic Research Program of China(973 Program,Grant No.2014CB845800) by the National Natural Science Foundation of China(Grant No.11473012) 

主　　题：stars: neutron    planet star interactions    pulsars: individual (PSR J0738 4042) 

摘      要：Long term observations by Brook et al. reveal that the derivative of rotational frequency of PSR J0738-4042 changed abruptly in 2005. Originally, the spin-down rate was relatively stable, with the rotational frequency derivative being - 1.14 x 10-14 s-2. After September 2005, the derivative began to rise. About 1000 days later, it arrived at another relatively stable value of about -0.98 x 10-24 s-2, indicating that the pulsar is spinning-down relatively slowly. To explain the observed change in spin-down rate, we resort to an asteroid disrupted by PSR J0738-4042. In our model, the orbital angular momentum of the asteroid is assumed to be parallel to that of the rotating pulsar, so that the pronounced reduction in the spin-down rate can be naturally explained as due to the transfer of angular momentum from the disrupted material to the central pulsar. The derived magnetospheric radius is about 7.0 x 109 cm, which is smaller than the tidal disruption radius （8.7 x 10^10cm）. Our model is self-consistent. It is shown that the variability in the spin-down rate of PSR J0738-4042 can be quantitatively accounted for by accretion from the asteroid disrupted by the central pulsar.