论文标题
发现热核型I X射线爆发红外线：4U 1728-34的轨道时期的新极限
Discovery of a thermonuclear Type I X-ray burst in infrared: new limits on the orbital period of 4U 1728-34
论文作者
论文摘要
我们报告了从积聚中子星4U 1728-34（GX 354-0）中的热核I型X射线爆发的红外爆发的检测。与XMM-Newton（0.7-12 KEV），Nustar（3-79 KeV）和Hawk-I@VLT（2.2 $μ$ M）同时进行观察。我们在两个频段的发射峰之间的落后时间为$ 4.75 \ pm 0.5 $。由于滞后的长度和IR爆发的形状，我们发现，如此巨大的延迟最合理的原因是同伴星对I型I型爆破X射线的重新处理。可以使用中子星和同伴之间的推断距离来限制系统的轨道周期，我们发现该系统大于$ \ sim $ 66分钟（甚至$ \ gtrsim $ 2小时，对于现实的倾斜度$ <75^\ circ $）。这比目前暂定估计的$ \ sim 11 $分钟要大得多。我们讨论了对二进制的性质的物理含义，并得出结论，最有可能4U 1728-34的同伴是氦气之星。
We report the detection of an infrared burst lagging a thermonuclear Type I X-ray burst from the accreting neutron star 4U 1728-34 (GX 354-0). Observations were performed simultaneously with XMM-Newton (0.7-12 keV), NuSTAR (3-79 keV) and HAWK-I@VLT (2.2$μ$m). We measure a lag of $4.75 \pm 0.5$ s between the peaks of the emission in the two bands. Due to the length of the lag and the shape of the IR burst, we found that the most plausible cause for such a large delay is reprocessing of the Type I burst X-rays by the companion star. The inferred distance between the neutron star and the companion can be used to constrain the orbital period of the system, which we find to be larger than $\sim$ 66 minutes (or even $\gtrsim$ 2 hours, for a realistic inclination $< 75^\circ$). This is much larger than the current tentatively estimated period of $\sim 11$ minutes. We discuss the physical implications on the nature of the binary and conclude that most likely the companion of 4U 1728-34 is a helium star.
