AI 中文总结
本研究提出PSR J0435+3233为等级三重系统，解释其高自转减慢率源于第三体的变化加速度，该模型可匹配观测结果，或能更严格约束强等效原理违反情况。
AI 中文摘要
背景：近期PSR J0435+3233的脉冲星计时星历显示，该毫秒脉冲星（MSP）的自转减慢率远高于其他已观测到的MSP，这对我们理解MSP的形成与演化构成了挑战。目的：我们提出该系统是一个等级三重系统，其高自转减慢率由宽轨道上的伴星（第三体）引起的变化加速度所致。方法：我们利用PSR J0435+3233的射电与伽马射线观测数据，结合脉冲星计时方法确定该系统的属性。结果：我们发现等级三重计时模型能够描述PSR J0435+3233的计时观测结果，且该模型可追溯到2008年费米大面积望远镜（LAT）数据起始时的伽马射线脉冲辐射。固有自转减慢率仍不确定，因其与外轨道参数相关，但大自转减慢率已被排除，固有率至少比观测率低两个数量级，与银河系其他MSP一致。我们确定了位于脉冲星位置11毫角秒处的一颗恒星为第三体的光学对应体。结合1.5-2.5千秒差距的距离与颜色，我们推断该第三体是一颗质量为1.2倍太阳质量的F型主序星。它与脉冲星双星共同绕质心运动，轨道偏心率e≈0.6，轨道周期约70年，轨道倾角可能较小。结论：我们得出PSR J0435+3233是一个等级三重系统的结论。我们讨论了继续研究该系统的动机与前景：对外侧恒星的光谱测量及持续的天体测量测量将得出质量比与倾角估计，而持续的脉冲星计时可能比对PSR J0337+1715的当前测量更严格地约束强等效原理的违反情况。
英文摘要
Context. The recent pulsar timing ephemeris of PSR J0435+3233 indicates that this millisecond pulsar (MSP) has a spin-down rate that is much higher than observed in other MSPs and challenges our understanding of the formation and evolution of MSPs. Aims. We propose that this system is a hierarchical triple, and that the high spin-down rate is caused by varying acceleration due to a tertiary in a wide orbit. Methods. We use pulsar timing methods with radio and gamma-ray observations of PSR J0435+3233 to determine the system properties. Results. We find that a hierarchical triple timing model describes the timing observations of PSR J0435+3233 and that this results in the detection of gamma-ray pulsations back to the beginning of the Fermi Large Area Telescope (LAT) data in 2008. The intrinsic spin-down rate remains uncertain as it correlates with the parameters of the outer orbit, but large spin-down rates are excluded and the intrinsic rate is at least two orders of magnitude lower than the observed rate, in line with other Galactic MSPs. We identify a star located 11 mas from the pulsar position as the optical counterpart to the tertiary companion. From the 1.5-2.5 kpc distance and colours, we infer that the tertiary is a 1.2 solar mass F-type main-sequence star. Along with the pulsar binary, it orbits the common centre of mass with an eccentric (e ~ 0.6), wide (~ 70 yr) orbit that is likely seen at a low orbital inclination. Conclusions. We conclude that PSR J0435+3233 is a hierarchical triple system. We discuss the motivation and prospects for the continued study of this system. Spectral measurements of the outer star in addition to continued astrometric measurements will yield mass ratio and inclination estimates, while continued pulsar timing may yield a tighter constraint on violations of the Strong Equivalence Principle than are currently obtained from PSR J0337+1715.
CommentsSubmitted to Astronomy and Astrophysics
