标题： 极端TeV耀变体和星系际磁场的下限 显示英文标题

标题： Extreme TeV Blazars and Lower Limits on Intergalactic Magnetic Fields

摘要： 宇宙空洞中的星际磁场（IGMF）可以通过其对由TeV伽马射线源引发的电磁级联的影响进行间接探测，例如耀变体，这是活动星系核的一个子类。在TeV能量下足够明亮的耀变体，“极端TeV耀变体”，如果IGMF不是太大，可以通过级联中电子的逆康普顿散射产生可检测的次级辐射。我们回顾了文献中最近的工作，这些工作利用这一想法对三个被TeV探测的耀变体——1ES 0229+200、1ES 1218+304和RGB J0710+591进行了IGMF的约束研究，并且在相同框架下还研究了另外四个硬谱TeV耀变体。通过一个新开发的详细三维粒子追踪蒙特卡洛模拟代码，结合所有主要的QED效应和宇宙膨胀效应，我们研究了主要不确定性的影响，如源的光谱特性、紫外线-远红外星系外背景光（EBL）强度的不确定性、未充分采样的极高能（VHE；能量>100 GeV）覆盖范围、过去伽马射线发射的历史、源与观测者几何结构以及AGN喷流多普勒因子。这些影响对最近报告的IGMF下限的含义被彻底检查，以得出目前可用的数据与零IGMF假设相容的结论。 显示英文摘要

摘要： The intergalactic magnetic field (IGMF) in cosmic voids can be indirectly probed through its effect on electromagnetic cascades initiated by a source of TeV gamma rays, such as blazars, a subclass of active galactic nuclei. Blazars that are sufficiently luminous at TeV energies, "extreme TeV blazars", can produce detectable levels of secondary radiation from inverse Compton scattering of the electrons in the cascade, provided that the IGMF is not too large. We reveiw recent work in the literature which utilizes this idea to derive constraints on the IGMF for three TeV-detected blazars-1ES 0229+200, 1ES 1218+304, and RGB J0710+591, and we also investigate four other hard-spectrum TeV blazars in the same framework. Through a recently developed detailed 3D particle tracking Monte Carlo simulation code, incorporating all major effects of QED and cosmological expansion, we research effects of major uncertainties such as the spectral properties of the source, uncertainty in the intensity of the UV - far IR extragalactic background light (EBL), under-sampled Very High Energy (VHE; energy > 100 GeV) coverage, past history of gamma-ray emission, source vs. observer geometry, and jet AGN Doppler factor. The implications of these effects on the recently reported lower limits of the IGMF are thoroughly examined to conclude that presently available data are compatible with a zero IGMF hypothesis.