论文标题
X射线瞬态XTE J1739-285的硬幂律频谱截止和光盘反射特征的证据
Evidence of hard power-law spectral cutoff and disc reflection features from the X-ray transient XTE J1739-285
论文作者
论文摘要
我们报告几乎同时\ nicer {}和\ nustar {}对已知X射线瞬态XTE〜J1739-285的观察。这些观察结果提供了该中子星X射线瞬变的第一个灵敏的硬X射线光谱。该消息来源于2月19日在硬光谱状态下观察到，亮度为$ 0.007 $占爱丁顿限制的$ 0.007。宽带$ 1-70 \ kev {} $ \ nicer {}和\ nustar {}观察清楚地检测到在$ 34-40 \ kev {} $的硬光谱成分的截止值时，当连续体由软热组件和硬性强大法律组件拟合时。该功能是在此源中首次检测到的。此外，这些频谱显示了圆盘反射的证据 - 相对扩大的fe k $α$ line在$ 5-8 \ kev {} $和$ 10-20 \ kev {} $ Energy Band中的Compton Hump。在此源之前尚未确定积聚盘反射功能。通过积聚光盘反射建模，我们首次将内光盘的半径限制为$ r_ {in} = 3.1 _ { - 0.5}^{+1.8} \; r_; r_ {isco} $。此外，我们发现低倾斜度，$ i \ sim 33^{0} $。假设磁层负责恒星表面上方的内积盘的这种截断，我们在磁场上的磁场上建立了上限为$ 6.2 \ times 10^8 $ g。
We report on the nearly simultaneous \nicer{} and \nustar{} observations of the known X-ray transient XTE~J1739-285. These observations provide the first sensitive hard X-ray spectrum of this neutron star X-ray transient. The source was observed on 2020 February 19 in the hard spectral state with a luminosity of $0.007$ of the Eddington limit. The broadband $1-70 \kev{}$ \nicer{} and \nustar{} observation clearly detects a cutoff of the hard spectral component around $34-40 \kev{}$ when the continuum is fitted by a soft thermal component and a hard power-law component. This feature has been detected for the first time in this source. Moreover, the spectrum shows evidence for disc reflection -- a relativistically broadened Fe K$α$ line around $5-8 \kev{}$ and a Compton hump in the $10-20 \kev{}$ energy band. The accretion disc reflection features have not been identified before from this source. Through accretion disc reflection modeling, we constrain the radius of the inner disc to be $R_{in}=3.1_{-0.5}^{+1.8}\;R_{ISCO}$ for the first time. In addition, we find a low inclination, $i\sim 33^{0}$. Assuming the magnetosphere is responsible for such truncation of the inner accretion disc above the stellar surface, we establish an upper limit of $6.2\times 10^8$ G on the magnetic field at the poles.
