标题： NuSTAR对伽马射线发射X射线双星和过渡毫秒脉冲星候选体1RXS J154439.4-112820的观测 显示英文标题

标题： A NuSTAR Observation of the Gamma-Ray-Emitting X-ray Binary and Transitional Millisecond Pulsar Candidate 1RXS J154439.4-112820

摘要： 我呈现了一次40千秒的核光谱望远镜阵列（NuSTAR）观测，对象是最近发现的低光度X射线双星和过渡毫秒脉冲星（tMSP）候选体1RXS J154439.4-112820，该天体与高能伽马射线源3FGL J1544.6--1125有关。 该系统在约30 keV范围内被探测到，其幂律谱延伸，并且在软X射线中观察到的两个通量水平之间存在快速的大振幅变化。 这些发现进一步表明，1RXS J154439.4-112820属于与附近公认的tMSPs PSR J1023+0038和XSS J12270-4859同一类天体，因此几乎可以肯定它包含一个以低光度吸积的毫秒脉冲星。 我还基于覆盖过去$\sim$十年的档案光学、紫外、X射线和$\gamma$-ray光变曲线，研究了1RXS J154439.4-112820的长期吸积历史。 在整个期间，该源在所有波长上都保持相似的通量水平，这表明它没有经历过长时间的非吸积射电脉冲星状态，但未来可能会自发地经历这样的状态转变。 显示英文摘要

摘要： I present a 40 kilosecond Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the recently identified low-luminosity X-ray binary and transitional millisecond pulsar (tMSP) candidate 1RXS J154439.4-112820, which is associated with the high-energy gamma-ray source 3FGL J1544.6--1125. The system is detected up to ~30 keV with an extension of the same power-law spectrum and rapid large-amplitude variability between two flux levels observed in soft X-rays. These findings provide further evidence that 1RXS J154439.4-112820 belongs to the same class of objects as the nearby bona fide tMSPs PSR J1023+0038 and XSS J12270-4859 and therefore almost certainly hosts a millisecond pulsar accreting at low luminosities. I also examine the long-term accretion history of 1RXS J154439.4-112820 based on archival optical, ultraviolet, X-ray, and $\gamma$-ray light curves covering the past $\sim$decade. Throughout this period, the source has maintained similar flux levels at all wavelengths, which is an indication that it has not experienced prolonged episodes of a non-accreting radio pulsar state but may spontaneously undergo such a state transformation in the future.