Large-Scale Blazar Jets: Clues on High-Energy Emission from Low-Frequency Radio Observations

大型 Blazer 喷气机：低频射电观测中高能发射的线索

• 批准号: 467205756
• 负责人: Professor Dr. Matthias Kadler
• 金额: --
• 依托单位: Hamburger Sternwarte
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/467205756?language=en
• 关键词: Large; Scale; Blazar; Jets; Clues

More than 100 AGN jets have been imaged with arcsec resolution in the optical and X-ray band. In the case of low-power FR I sources, the X-ray jet emission can generally be interpreted as an extension of the radio synchrotron spectrum. In contrast to this, the radio, optical and X-ray broadband spectra of FR II jets clearly show that other emission processes are at play. Originally, inverse-Comptonization of CMB photons (IC/CMB) was suggested. This model requires bulk relativistic motion on kiloparsec scales (which is difficult to observe) and an electron energy distribution extending down to Lorentz factors smaller than ∼100, which is lower than the energy regimes traced by GHz instruments like the VLA. Very recently, first results of high-resolution LOFAR observations of AGN jets involving international baselines at hundreds of MHz found radio flux densities in one quasar well below the values estimated by extrapolating the GHz spectra and thus falling short of explaining the observed X-ray knot emission in terms of the IC/CMB model. In this project, we will perform a systematic LOFAR study of the long-wavelength radio emission of quasar jets on kiloparsec scales and combine this with shorter-wavelength radioand higher-energy optical and X-ray broadband spectral data to test the IC/CMB and alternative emission models. We will further develop and optimize high-resolution imaging techniques at the low and ultralow radio frequencies in total and linearly-polarized intensity with LOFAR-VLBI techniques to measure magnetic-field geometries and constrain jet-composition and emission models.

在光学和X射线波段，已经对100多个活动星系核喷流进行了角秒分辨率的成像。在低功率FR I源的情况下，X射线喷流发射通常可以解释为射电同步加速器谱的延伸。与此相反，FR II喷流的射电、光学和X射线宽带光谱清楚地表明，其他发射过程也在起作用。 最初，提出了CMB光子的逆康普顿化（IC/CMB）。这个模型需要千秒差距尺度上的相对论运动（这是很难观察到的）和电子能量分布延伸到小于1000的洛伦兹因子，这低于GHz仪器（如VLA）跟踪的能量状态。最近，活动星系核喷流的高分辨率LOFAR观测的第一个结果涉及数百MHz的国际基线，发现一个类星体的射电通量密度远低于通过外推GHz光谱估计的值，因此无法解释观察到的X射线结发射的IC/CMB模型。在这个项目中，我们将进行一个系统的LOFAR研究的长波无线电发射的类星体喷流在千秒差距尺度和联合收割机这与较短的波长无线电和高能光学和X射线宽带光谱数据测试IC/CMB和替代的排放模型。 我们将进一步开发和优化在低和超低无线电频率的总和线偏振强度与LOFAR-VLBI技术的高分辨率成像技术，以测量磁场的几何形状和约束喷流的组成和排放模型。