论文标题
使用Astrosat和XMM-Newton的积聚毫秒的X射线脉冲SAX J1748.9-2021的宽带外观
A broadband look of the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 using AstroSat and XMM-Newton
论文作者
论文摘要
萨克斯J1748.9-2021是位于球形群集NGC 6440的瞬态增强型X射线脉冲星。我们报告萨克斯sax J1748.9-2021的频谱和时序分析，在淡淡的范围和较短的频率上，我们在2017年的淡淡频率上进行了频率。 442.361098（3）Hz。从3-7 KEV和7-20 KEV能带获得的脉冲曲线表明，基本成分的恒定分数幅度约为0.5％，与先前观察到的能量脉冲谱依赖性相反。我们的Astrosat观察结果表明，来源处于硬光谱状态。可以用单个温度黑体和热构造来很好地描述来自SXT和LAXPC的1-50 keV光谱。此外，我们发现来自XMM-Newton（Epic-PN）和Astrosat（SXT+LAXPC）的组合光谱表明我们使用反射模型Xillvercp建模的铁（Fe K $α$）线的形式存在反射特征。在Astrosat/LaxPC观察过程中观察到的两次X射线爆发之一显示，由于Hot Corona对热光子进行了热散射，因此X射线发射（> 30 KEV）。对爆发进行的时间分析分析揭示了黑体的发射半径的复杂演化，以表明轻度光球半径膨胀。
SAX J1748.9-2021 is a transient accretion powered millisecond X-ray pulsar located in the Globular cluster NGC 6440. We report on the spectral and timing analysis of SAX J1748.9-2021 performed on AstroSat data taken during its faint and short outburst of 2017. We derived the best-fitting orbital solution for the 2017 outburst and obtained an average local spin frequency of 442.361098(3) Hz. The pulse profile obtained from 3-7 keV and 7-20 keV energy bands suggest constant fractional amplitude ~0.5% for fundamental component, contrary to previously observed energy pulse profile dependence. Our AstroSat observations revealed the source to be in a hard spectral state. The 1-50 keV spectrum from SXT and LAXPC on-board AstroSat can be well described with a single temperature blackbody and thermal Comptonization. Moreover, we found that the combined spectra from XMM-Newton (EPIC-PN) and AstroSat (SXT+LAXPC) indicated the presence of reflection features in the form of iron (Fe K$α$) line that we modeled with the reflection model xillvercp. One of the two X-ray burst observed during the AstroSat/LAXPC observation showed hard X-ray emission (>30 keV) due to Compton up-scattering of thermal photons by the hot corona. Time resolved analysis performed on the bursts revealed complex evolution in emission radius of blackbody for second burst suggestive of mild photospheric radius expansion.
