论文标题
Maxi J1957+032：超紧凑型二进制中的新的积聚毫秒X射线脉冲星
MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary
论文作者
论文摘要
在〜314 Hz（3.2 ms）处的相干X射线脉动的检测将最大J1957+032分类为快速旋转的增值中子星。我们介绍了在最新爆发过程中收集的更好的观察结果进行的时间和光谱分析。 X射线脉动的多普勒调制揭示了二进制系统的超紧凑性质，其特征在于轨道周期约1小时，而投影的半高轴为14 lt-ms。中子恒星二元质量函数表明，假设中子星质量为1.4 mSUN，二元倾斜角度低于60度，则最小供体质量为1.7E-2 MSUN。该假设是由源X射线光曲线中缺乏蚀或倾角的支持。我们将爆发中源的0.5-10 keV能量谱描述为与中子星表面发射的相对较冷的黑体样热发射的叠加，以及具有与典型硬状态一致的光子指数的组合成分。我们没有找到铁K-α线或反射成分的证据。
The detection of coherent X-ray pulsations at ~314 Hz (3.2 ms) classifies MAXI J1957+032 as a fast-rotating, accreting neutron star. We present the temporal and spectral analysis performed using NICER observations collected during the latest outburst of the source. Doppler modulation of the X-ray pulsation revealed the ultra-compact nature of the binary system characterised by an orbital period of ~1 hour and a projected semi-major axis of 14 lt-ms. The neutron star binary mass function suggests a minimum donor mass of 1.7e-2 Msun, assuming a neutron star mass of 1.4 Msun and a binary inclination angle lower than 60 degrees. This assumption is supported by the lack of eclipses or dips in the X-ray light curve of the source. We characterised the 0.5-10 keV energy spectrum of the source in outburst as the superposition of a relatively cold black-body-like thermal emission compatible with the emission from the neutron star surface and a Comptonisation component with photon index consistent with a typical hard state. We did not find evidence for iron K-alpha lines or reflection components.
