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arXiv 2111.01641astro-ph.HE
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XTE J1810-197巨脉冲的射电和X射线观测

Radio and X-ray observations of giant pulses from XTE J1810-197

M. Caleb, K. Rajwade, G. Desvignes, B. W. Stappers, A. G. Lyne, P. Weltevrede, M. Kramer, L. Levin, M. Surnis

摘要:

我们介绍了自2018年底无线电重新激活以来对磁星XTE J1810 $-$ 197进行两年无线电和X射线监测的结果。对来自Lovell和MkII望远镜在1564 MHz和Effelsberg望远镜在6 GHz的射电观测的单脉冲分析导致在MJD 58858和59117之间总共检测到91个巨脉冲(GP)。这些GP似乎局限于两个特定的相位范围(0.473 <= 0.502$和0.541 <= 0.567)。我们还观察到,GP发射的第一次检测对应于自旋下降速率的最小值。对MJD 59009和59096同时进行了无线电和X射线观察。NICER的0.5-10 keV X射线谱具有两组分黑体模型的特征,该模型可以解释为中子星极盖上的两个热点。黑体温度随着时间的推移而降低,与以前的爆发一致,而脉冲分数的变化并不遵循相同的趋势,在以前的爆发。XTE J1810-197的射电和X射线通量在爆发的初始阶段(MJD 58450 - MJD 58550)是相关的,后来观察到射电通量的增加,这可能与GP的出现有关。我们认为,目前的爆发相比,前一个的演化差异可以归因于中子星的几何形状的变化。

英文摘要:

We present the results of two years of radio and X-ray monitoring of the magnetar XTE J1810$-$197 since the radio re-activation in late 2018. Single pulse analysis of radio observations from the Lovell and MkII telescopes at 1564 MHz and the Effelsberg telescope at 6 GHz has resulted in the detection of a total of 91 giant pulses (GPs) between MJDs 58858 and 59117. These GPs appear to be confined to two specific phase ranges (0.473 <= ϕ<= 0.502$ and 0.541 <= ϕ<= 0.567). We also observe that the first detection of GP emission corresponds to a minimum in the spin-down rate. Simultaneous radio and X-ray observations were performed on MJDs 59009 and 59096. The 0.5-10 keV X-ray spectrum from NICER is well characterised by a two component blackbody model that can be interpreted as two hot spots on the polar cap of the neutron star. The blackbody temperature decreases with time, consistent with the previous outburst, while the change in the pulsed fraction does not follow the same trend as was seen in the previous outburst. The radio and X-ray flux of XTE J1810-197 are correlated during the initial phase of the outburst (MJD 58450 - MJD 58550) and an increase in the radio flux is observed later that may be correlated to the onset of GPs. We argue that the disparity in the evolution of the current outburst compared to the previous one can be attributed to a change in geometry of the neutron star.

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