利用NuSTAR和NICER对2S 1553$-$542在2024年爆发的定时和光谱分析
Timing and Spectral Analysis of the 2024 Outburst of 2S 1553$-$542 with NuSTAR and NICER
浏览论文内容
中文总结 AI 辅助
该研究利用NuSTAR和NICER对2S 1553$-$542在2024年爆发进行定时和光谱分析，测量脉冲周期等，分析光谱特征获回旋能量等，还搜索NICER GTIs中的mHz变异性，虽有局部过剩但视为候选而非确定检测。
中文摘要 AI 辅助
我们报告了一项利用NuSTAR和NICER观测对Be/X射线双星脉冲星2S~1553$-$542在2024年爆发的定时和光谱研究。从NuSTAR光变曲线测量出脉冲周期为9.285022±0.000001秒。能量分辨脉冲轮廓以单峰为主，在12 - 22 keV波段最清晰地显示出翼状结构。脉冲分数保持在60%以上并随能量增加。相位平均NuSTAR光谱由吸收黑体加截止幂律连续谱、铁发射线和回旋吸收特征描述。利用“cyclabs”模型得到回旋能量约为24.1 keV，对应磁场强度约为3×10¹² G。相位分辨光谱表明连续谱和回旋线参数随脉冲相位变化，且在脉冲翼相位附近谱线约束变差。我们还使用小波分析和基于CEEMDAN的希尔伯特 - 黄变换在短NICER GTIs中搜索瞬态mHz变异性，发现了约10 mHz和20 mHz附近的局部过剩，但因其短曝光、COI效应、红噪声波动和缺乏良好约束的傅里叶峰而将其视为候选mHz变异性而非确定的mHz QPO检测。
英文摘要
We report a timing and spectral study of the 2024 outburst of the Be/X-ray binary pulsar 2S~1553$-$542 using \textit{NuSTAR} and \textit{NICER} observations. From the \textit{NuSTAR} light curve we measure a pulse period of $9.285022\pm0.000001$~s. The energy-resolved pulse profiles are dominated by a single peak and show a wing-like structure most clearly in the $12$--$22$~keV band. The pulsed fraction remains above 60\% and increases with energy. The phase-averaged \textit{NuSTAR} spectrum is described by an absorbed blackbody plus cutoff power-law continuum, together with an iron emission line and a cyclotron absorption feature. Using the \texttt{cyclabs} model, we obtain a cyclotron energy of $E_{\rm cyc}\simeq24.1$~keV, corresponding to a magnetic field strength of $B\sim3\times10^{12}$~G. Phase-resolved spectroscopy shows that the continuum and cyclotron-line parameters vary with pulse phase, and that the line becomes poorly constrained around the pulse-wing phase. We also searched the short \textit{NICER} GTIs for transient mHz variability using wavelet analysis and a CEEMDAN-based Hilbert--Huang transform. Localized excesses near $\sim10$~mHz and $\sim20$~mHz are found, but the short exposures, COI effects, red-noise fluctuations, and the lack of a well-constrained Fourier peak limit their significance. We therefore treat them as candidate mHz variability rather than firm mHz QPO detections.
