论文标题
2022年爆发的计时分析毫秒X射线Pulsar SAX J1808.4 $ - $ 3658：轨道收缩的提示
Timing analysis of the 2022 outburst of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658: hints of an orbital shrinking
论文作者
论文摘要
我们介绍了脉冲时序分析，对毫秒X射线X射线Pulsar sax J1808.4 $ - $ 3658的脉冲时间分析在8月19日开始的爆发期间。类似于以前的爆发，从$ \ simeq 1 \ simeq 1 \ simeq 1 \ \ simeq 1 \ \ sime11^{36} {36} \ n er， s^{ - 1}}} $在大约一周内，Pulsar以$ \ sim 1 $一个月的回流阶段输入。比较爆发期间的平均脉冲星旋转频率与先前测量的频率的比较证实了$ \dotν_ {\ textrm {sd}} = - （1.15 \ pm0.06）\ times 10^{ - 15} { - 15} \，\，\，\，\，\，\ mathrm { $ \大约10^{26} \，\ Mathrm {g \，cm^3} $旋转磁性偶极子。在过去的二十年中，轨道相的演变首次显示了轨道时期减少的证据。轨道的长期行为由$ \ sim 11 \，\ mathrm {s} $调制轨道相位时期的调制与$ \ sim 21 \，\ mathrm {yr {yr} $一致。我们讨论了观察到的演变，以伴侣恒星的轨道和质量四极的变化之间的耦合。
We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4$-$3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of $\simeq 1\times10^{36} \, \mathrm{erg \, s^{-1}}$ in about a week, the pulsar entered in a $\sim 1$ month-long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of $\dotν_{\textrm{SD}}=-(1.15\pm0.06)\times 10^{-15} \, \mathrm{Hz\,s^{-1}}$, compatible with the spin-down torque of a $\approx 10^{26} \, \mathrm{G \, cm^3}$ rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behaviour of the orbit is dominated by a $\sim 11 \, \mathrm{s}$ modulation of the orbital phase epoch consistent with a $\sim 21 \, \mathrm{yr}$ period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star.
