Time Delay of Cascade Radiation for TeV Blazars and the Measurement of the Intergalactic Magnetic Field

Recent claims that the strength B IGMF of the intergalactic magnetic field (IGMF) is 10--15 G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background light. This limit depends on an assumption that the mean blazar...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2011-06, Vol.733 (2), p.L21-jQuery1323917344317='48'
Main Authors: Dermer, Charles D, Cavadini, Massimo, Razzaque, Soebur, Finke, Justin D, Chiang, James, Lott, Benoit
Format: Article
Language:English
Subjects:
ASTRONOMY AND ASTROPHYSICS
Astrophysics
galaxies: jets
gamma rays: galaxies
High Energy Astrophysical Phenomena
Physics
radiation mechanisms: non-thermal
Sciences of the Universe
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Summary:Recent claims that the strength B IGMF of the intergalactic magnetic field (IGMF) is 10--15 G are based on upper limits to the expected cascade flux in the GeV band produced by blazar TeV photons absorbed by the extragalactic background light. This limit depends on an assumption that the mean blazar TeV flux remains constant on timescales 2(B IGMF/10--18G)2/(E/10 GeV)2 yr for an IGMF coherence length 1 Mpc, where E is the measured photon energy. Restricting TeV activity of 1ES 0229+200 to 3-4 years during which the source has been observed leads to a more robust lower limit of B IGMF 10--18 G, which can be larger by an order of magnitude if the intrinsic source flux above 5-10 TeV from 1ES 0229+200 is strong.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/733/2/L21