论文标题
从魔术和费米/LAT观测的时间变异性的1ES 0229+200的下降磁场上的下限
A lower bound on intergalactic magnetic fields from time variability of 1ES 0229+200 from MAGIC and Fermi/LAT observations
论文作者
论文摘要
通过伽马射线通过白层间培养基传播的影响诱导的遥远的TEV源周围的延长和延迟发射可用于测量白乳磁场(IGMF)。我们搜索从硬光谱Tev Blazar 1ES 0229+200的延迟GEV排放,其目标是检测或限制TEV Gamma射线传播过程中通过绘制介质产生的IGMF依赖性二次通量。我们分析了5年时间内的最新魔术观察结果,并通过H.E.S.S.的历史数据进行补充。 Veritas望远镜以及费米/LAT望远镜的12年长期暴露。我们使用它们来追踪GEV-TEV频段中十年半的时间的源演变。我们使用蒙特卡洛模拟来预测由源变异性调节的延迟次级伽马射线通量,如TEV波段观测所揭示的那样。然后,我们将各种假定IGMF强度的这些预测与伽马射线演化的所有可用测量结果进行比较。我们发现,在14年的观察时间范围内,能量范围超过200 GEV的源通量经历了其平均值的变化。 Fermi/LAT可访问1-100 GEV能量范围的通量变异性的证据。对于长相关长度IGMF和B> 1E-14 g的IgMF而言,由于静脉内培养基中产生的电磁级联反射而导致的可变性的未检测。尽管比先前从费米/LAT数据分析得出的弱弱,但该界限基于保守的内在源频谱估计,并考虑了TEV能量频段中源可变性的细节。我们讨论了这种结合对宇宙学磁场的含义,这可能解释了宇宙的重子不对称。
Extended and delayed emission around distant TeV sources induced by the effects of propagation of gamma rays through the intergalactic medium can be used for the measurement of the intergalactic magnetic field (IGMF). We search for delayed GeV emission from the hard-spectrum TeV blazar 1ES 0229+200 with the goal to detect or constrain the IGMF-dependent secondary flux generated during the propagation of TeV gamma rays through the intergalactic medium. We analyze the most recent MAGIC observations over a 5 year time span and complement them with historic data of the H.E.S.S. and VERITAS telescopes along with a 12-year long exposure of the Fermi/LAT telescope. We use them to trace source evolution in the GeV-TeV band over one-and-a-half decade in time. We use Monte Carlo simulations to predict the delayed secondary gamma-ray flux, modulated by the source variability, as revealed by TeV-band observations. We then compare these predictions for various assumed IGMF strengths to all available measurements of the gamma-ray flux evolution. We find that the source flux in the energy range above 200 GeV experiences variations around its average on the 14 years time span of observations. No evidence for the flux variability is found in 1-100 GeV energy range accessible to Fermi/LAT. Non-detection of variability due to delayed emission from electromagnetic cascade developing in the intergalactic medium imposes a lower bound of B>1.8e-17 G for long correlation length IGMF and B>1e-14 G for an IGMF of the cosmological origin. Though weaker than the one previously derived from the analysis of Fermi/LAT data, this bound is more robust, being based on a conservative intrinsic source spectrum estimate and accounting for the details of source variability in the TeV energy band. We discuss implications of this bound for cosmological magnetic fields which might explain the baryon asymmetry of the Universe.