文章基本信息

标题：Constraining Intergalactic Magnetic Fields
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作者：S. Inoue
期刊名称：PoS - Proceedings of Science
印刷版ISSN：1824-8039
出版年度：2011
卷号：2011
期号：AGN2011
出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：High-energy gamma rays from blazars may be accompanied by secondary emission components due to e−e+ pairs produced in interactions of primary TeV photons with the extragalactic background light, which can provide a unique probe of weak intergalactic magnetic fields (IGMFs) through their characteristic time delay (pair echos) or angular extension (beamed pair halos). Together with theoretical expectations, we briefly review recent claims of lower bounds to IGMF strengths in the range B ∼ 10−18 −10−15 G inferred from observational upper limits on such components, and caution that they are dependent on unproven assumptions regarding the primary emission during epochs unobserved by TeV telescopes. Utilizing only simultaneously observed GeV-TeV light curves with a minimum of such assumptions, our conservative limits on the pair echo emission for Mrk 501 imply a weak bound of B & 10−20 G for a field coherence length of 1 kpc, which is nevertheless evidence for non-zero IGMFs that is more robust compared to previous studies. We comment on future prospects in the CTA era, emphasizing the need to positively detect the secondary components in order to obtain more definitive information on IGMFs.