High-energy neutrinos are a promising tool for identifying astrophysical sources of high and ultra-high energy cosmic rays (UHECR). Prospects of detecting neutrinos at high energies ($\gtrsim$TeV) from blazars have been boosted after the recent association of IceCube-170922A and TXS 0506+056. We investigate the high-energy neutrino, IceCube-190331A, a high-energy starting event (HESE) with a high likelihood of being astrophysical in origin. We initiated a Swift/XRT and UVOT tiling mosaic of the neutrino localisation, and followed up with ATCA radio observations, compiling a multiwavelength SED for the most likely source of origin. NuSTAR observations of the neutrino location and a nearby X-ray source were also performed. We find two promising counterpart in the 90% confidence localisation region and identify the brightest as the most likely counterpart. However, no Fermi/LAT $\gamma$-ray source and no prompt Swift/BAT source is consistent with the neutrino event. At this point it is unclear whether any of the counterparts produced IceCube-190331A. We note that the Helix Nebula is also consistent with the position of the neutrino event, and we calculate that associated particle acceleration processes cannot produce the required energies to generate a high-energy HESE neutrino.

中文翻译：

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IceCube-190331A 对应物的多信使观测

高能中微子是确定高能和超高能宇宙射线 (UHECR) 天体物理来源的有前途的工具。在最近将 IceCube-170922A 和 TXS 0506+056 结合之后，探测来自耀变体的高能（$\gtrsim$TeV）中微子的前景得到了提升。我们研究了高能中微子 IceCube-190331A，这是一个高能起始事件 (HESE)，很有可能是天体物理学起源。我们启动了中微子定位的 Swift/XRT 和 UVOT 拼贴马赛克，并跟进了 ATCA 无线电观测，为最可能的来源编制了多波长 SED。还对中微子位置和附近的 X 射线源进行了 NuSTAR 观测。我们在 90% 置信度定位区域中找到了两个有希望的对应物，并将最亮的对应物确定为最可能的对应物。然而，没有 Fermi/LAT $\gamma$ 射线源和提示 Swift/BAT 源与中微子事件一致。目前尚不清楚是否有任何同行生产了 IceCube-190331A。我们注意到螺旋星云也与中微子事件的位置一致，我们计算出相关的粒子加速过程无法产生产生高能 HESE 中微子所需的能量。