天文学家发现“蜘蛛”脉冲星双星系统PSR B1744-24A中存在高度磁化环境

Highly Magnetized Environment in Spider Pulsar Binary System

        蜘蛛脉冲星双星系统包括一个毫秒脉冲星和一个小质量伴星。毫秒脉冲星的星风会逐渐剥离伴星的物质，同时脉冲星的射电辐射会受到伴星外流物质的影响。在这过程中伴星磁场对双星系统的演化和脉冲星辐射的掩食特征都会有显著的影响。 

        研究人员最近发现位于Terzan 5球状星团的蜘蛛脉冲星PSR B1744–24A4在经过伴星上合区的时候会产生圆偏振反转，圆偏振的反转现象起源于法拉第转换效应，表明该双星系统中存在高磁化的环境。同时研究人员还发现该脉冲星的法拉第旋转量在随机的轨道相位发生不规则、快速的变化。这些现象与部分重复快速射电暴表现出的演化特征类似。这些相似之处表明部分快速射电暴可能位于双星系统中。该工作2023年5月17日发表于《自然》杂志主刊。

       云南大学中国西南天文研究所杨元培副教授深度参与了该研究，对该发现的物理解释做出了重要贡献。

       发表文章：Li, D., et al. 2023, Nature, 618, 484. (https://doi.org/10.1038/s41586-023-05983-z)。

图1. 蜘蛛脉冲星 PSR B1744–24A4位于伴星轨道上合区附近时产生的圆偏振反转。

Figure 1. Faraday conversion of Spider pulsar PSR B1744–24A4 occurs near the superior conjunction in the binary system.

    Spider pulsars are millisecond pulsars in short-period orbits with low-mass companion stars. The pulsars ablate plasma from the companion star, causing time delays and eclipses of the radio emission from the pulsar. The magnetic field of the companion has been proposed to strongly influence both the evolution of the binary system and the eclipse properties of the pulsar emission.

     Researchers recently observed a spider system PSR B1744 – 24A in the globular cluster Terzan 5 and measured semi-regular profile changes to the circular polarization, when the pulsar emission passes close to the companion. The observed result suggests that there is Faraday conversion where the radio wave tracks a reversal in the parallel magnetic field. Besides, some irregular, fast changes in the Faraday rotation measure were detected at random orbital phases. There are similarities between the unusual polarization behaviour of PSR B1744 – 24A and some repeating fast radio bursts, suggesting that a proportion of FRBs probably have binary companions. This work was published in Nature on May 17, 2023.

     Associate Prof. Yuanpei Yang, from the South-Western Institute for Astronomy Research, Yunnan University, contributes to the theoretical interpretation of this important discovery.

     Publication: Li, D., et al. 2023, Nature, 618, 484. (https://doi.org/10.1038/s41586-023-05983-z).