Abstract

We present our follow-up observations to search for an electromagnetic counterpart of the IceCube high-energy neutrino IceCube-170922A. Monitoring observations of a likely counterpart, TXS 0506+056, are also described. First, we quickly took optical and near-infrared images of seven flat-spectrum radio sources within the IceCube error region right after the neutrino detection and found a rapid flux decline of TXS 0506+056 in Kanata/HONIR J-band data. Motivated by this discovery, intensive follow-up observations of TXS 0506+056 were continuously performed, including our monitoring imaging observations, spectroscopic observations, and polarimetric observations in optical and near-infrared wavelengths. TXS 0506+056 showed a large-amplitude (∼1.0 mag) variability in a time scale of several days or longer, although no significant variability was detected in a time scale of a day or shorter. TXS 0506+056 also showed a bluer-when-brighter trend in optical and near-infrared wavelengths. Structure functions of the variabilities were examined and indicate that TXS 0506+056 is not a special blazar in terms of optical variability. Polarization measurement results of TXS 0506+056 are also discussed.

中文翻译：

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IceCube-170922A的后续观察：快速近红外变化检测和TXS 0506 + 056的密集监视

摘要

我们提出我们的后续观察结果，以寻找IceCube高能中微子IceCube-170922A的电磁对应物。还描述了可能的对应对象TXS 0506 + 056的监视结果。首先，我们在中微子探测到后立即在IceCube误差区域内迅速拍摄了七个平面光谱无线电源的光学和近红外图像，并在Kanata / HONIR J中发现TXS 0506 + 056的通量迅速下降。带数据。受这一发现的启发，连续进行了TXS 0506 + 056的深入随访观察，包括我们在光学和近红外波长下的监视成像观察，光谱观察和极化观察。TXS 0506 + 056在几天或更长时间的时间范围内显示出大幅度（〜1.0 mag）的变化，尽管在一天或更短的时间范围内未检测到明显的变化。TXS 0506 + 056在光学和近红外波长上也显示出更蓝变的趋势。检查了变异性的结构函数，结果表明TXS 0506 + 056在光学变异性方面不是特殊的危险。还讨论了TXS 0506 + 056的偏振测量结果。