论文标题
从X射线二进制Maxi J1807+132的发现热核I型X射线爆发
Discovery of Thermonuclear Type-I X-ray Bursts from the X-ray binary MAXI J1807+132
论文作者
论文摘要
Maxi J1807+132是2017年爆发时首次检测到的低质量X射线二进制(LMXB)。2017年爆发期间的观察结果不允许对紧凑型物体的性质进行明确的识别。 Maxi J1807+132在2019年再次爆发中被发现,并经常使用更好的人进行监测。在本文中,我们报告了五天的观察结果,在此期间,我们检测到三个热核(I型)X射线爆发,将系统鉴定为中子星LMXB。三型I爆发的时间分辨光谱显示出这些现象预期的典型特征。所有三型I爆发均显示出缓慢的升高和长时间的衰变,这表明H/H/H/H/H/H/H/H/H/H/燃料。我们没有发现任何类型的爆发达到爱丁顿的光度的强烈证据。但是,在假设最亮的X射线爆发发生光球半径膨胀的假设下,我们估计距离<12.4kpc上限。我们在Maxi J1807+132的I型爆发期间搜索了爆发振荡,但没有发现(<10%的振幅上限为95%的置信度)。最后,我们发现最明亮的I型爆发在上升过程中显示出〜1.6秒停顿。这种暂停类似于最近在明亮的I型X射线X射线Pulsar SAX J1808.4-3658中发现的较好型I类型的暂停。两种来源的I型爆发可以表明这种类型的停顿的事实表明,停顿的起源与燃烧燃料的组成,I型I型爆发的峰值光度无关,或者NS是X射线脉冲星。
MAXI J1807+132 is a low-mass X-ray binary (LMXB) first detected in outburst in 2017. Observations during the 2017 outburst did not allow for an unambiguous identification of the nature of the compact object. MAXI J1807+132 was detected in outburst again in 2019 and was monitored regularly with NICER. In this paper we report on five days of observations during which we detected three thermonuclear (Type-I) X-ray bursts, identifying the system as a neutron star LMXB. Time-resolved spectroscopy of the three Type-I bursts revealed typical characteristics expected for these phenomena. All three Type-I bursts show slow rises and long decays, indicative of mixed H/He fuel. We find no strong evidence that any of the Type-I bursts reached the Eddington Luminosity; however, under the assumption that the brightest X-ray burst underwent photospheric radius expansion, we estimate a <12.4kpc upper limit for the distance. We searched for burst oscillations during the Type-I bursts from MAXI J1807+132 and found none (<10% amplitude upper limit at 95% confidence level). Finally, we found that the brightest Type-I burst shows a ~1.6sec pause during the rise. This pause is similar to one recently found with NICER in a bright Type-I burst from the accreting millisecond X-ray pulsar SAX J1808.4-3658. The fact that Type-I bursts from both sources can show this type of pause suggests that the origin of the pauses is independent of the composition of the burning fuel, the peak luminosity of the Type-I bursts, or whether the NS is an X-ray pulsar.