Title: Degree-scale GeV "jets" from active and dead TeV blazars Show Chinese title

Title: 度尺度吉电子伏特“喷流”来自活跃和死亡的太电子伏特耀变体

Abstract: We show that images of TeV blazars in the GeV energy band should contain, along with point-like sources, degree-scale jet-like extensions. These GeV extensions are the result of electromagnetic cascades initiated by TeV gamma-rays interacting with extragalactic background light and the deflection of the cascade electrons/positrons in extragalactic magnetic fields (EGMF). Using Monte-Carlo simulations, we study the spectral and timing properties of the degree-scale extensions in simulated GeV band images of TeV blazars. We show that the brightness profile of such degree-scale extensions can be used to infer the lightcurve of the primary TeV gamma-ray source over the past 1e7 yr, i.e. over a time scale comparable to the life-time of the parent active galactic nucleus. This implies that the degree-scale jet-like GeV emission could be detected not only near known active TeV blazars, but also from "TeV blazar remnants", whose central engines were switched off up to ten million years ago. Since the brightness profile of the GeV "jets" depends on the strength and the structure of the EGMF, their observation provides additionally information about the EGMF. Show Chinese abstract

Abstract: 我们证明，在GeV能量波段中，TeV耀变体的图像应包含点状源以及度量级的喷流样扩展。这些GeV扩展是由于TeV伽马射线与星系外背景光相互作用而引发的电磁级联，以及级联电子/正电子在星系外磁场（EGMF）中的偏转结果。通过蒙特卡罗模拟，我们研究了TeV耀变体模拟GeV波段图像中度量级扩展的光谱和时间特性。我们证明，这种度量级扩展的亮度分布可用于推断过去1e7年内的原始TeV伽马射线源的光变曲线，即与母体活动星系核的寿命相当的时间尺度。这意味着，度量级的喷流样GeV辐射不仅可以在已知的活跃TeV耀变体附近检测到，还可以从“TeV耀变体残骸”中检测到，这些天体的中心引擎早在一千万年前就已关闭。由于GeV“喷流”的亮度分布依赖于EGMF的强度和结构，它们的观测还提供了关于EGMF的额外信息。