VLBA Observations of Neutrino-Candidate Blazars

中微子候选耀变体的 VLBA 观测

• 批准号: 447572188
• 负责人: Professor Dr. Matthias Kadler
• 金额: --
• 依托单位: Max-Planck-Institut für Radioastronomie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/447572188?language=en
• 关键词: VLBA; Observations; Neutrino; Candidate; Blazars

In the past four years, observational evidence has started piling up that some high-energy cosmic neutrinos detected by the IceCube observatory may be associated with blazars. Indeed, these powerful jets ejected from the centers of active galactic nuclei and pointed at a small angle to our line of sight have long been predicted to be bright neutrino emitters and to exhibit a neutrino spectrum flat enough to exceed the atmospheric background at sufficiently high energies above about 100 TeV. The most prominent example is the source TXS0506+056 that has been associated at 3-sigma significance with a high-energy IceCube neutrino detected in September 2017. Among all later neutrino-blazar associations, the highest-confidence one is represented by a 'gold-alert' neutrino detected in July 2019 in positional coincidence with the blazar PKS1502+106. We have successfully proposed for Very-Long-Baseline Interferometry (VLBI) observations of TXS 0506+056 and PKS 1502+106 in two separate proposals to the Very Long Baseline Array (VLBA). The observations of the two target sources were successfully performed shortly after the neutrino detections at multiple frequencies between 15 GHz and 86 GHz and in full polarization mode. The goal of this proposal is to obtain funding for a full analysis of the resulting observational data to study the VLBI jet structure of the two candidate neutrino blazars in total intensity and polarisation and to follow up on the evolution of their radio jets on milliarcsecond scales after the neutrino events using our observations and complementary data from the MOJAVE program. The VLBI data and analysis will be used to study blazar neutrino-emission models in which both the gamma radiation and the neutrino production are explained in a two-zone model of a structured jet. These models will be tested and their possible parameter ranges will be constrained by our VLBI data and complementary multi wavelength data.

在过去的四年里，观测证据已经开始堆积，冰立方天文台探测到的一些高能宇宙中微子可能与耀变体有关。事实上，这些从活动星系核中心喷射出来并指向我们视线的小角度的强大喷流，长期以来一直被预测为明亮的中微子发射体，并且在大约100 TeV以上的足够高的能量下，表现出足够平坦的中微子光谱，超过大气背景。最突出的例子是源TXS 0506 +056，它与2017年9月探测到的高能IceCube中微子有3 σ意义。 在所有后来的中微子-耀变体关联中，最高置信度的是2019年7月在与耀变体PKS 1502 +106位置重合的位置上检测到的“黄金警报”中微子。我们已经成功地提出了甚长基线干涉（VLBI）观测TXS 0506+056和PKS 1502+106在两个独立的建议，甚长基线阵列（VLBA）。在15 GHz和86 GHz之间的多个频率和全极化模式下的中微子探测之后不久，成功地对两个目标源进行了观测。该提案的目标是获得资金，对由此产生的观测数据进行全面分析，以研究两个候选中微子耀变体的VLBI喷流结构的总强度和偏振，并利用我们的观测结果和莫哈韦计划的补充数据，在中微子事件发生后跟踪其射电喷流在毫角秒尺度上的演变。VLBI数据和分析将用于研究耀变体中微子发射模型，其中伽马辐射和中微子产生都在结构喷流的两区模型中得到解释。这些模型将进行测试，其可能的参数范围将受到我们的VLBI数据和互补的多波长数据。