Probing intergalactic magnetic fields in the glast era through pair echo emission from TeV blazars

Kohta Murase, Keitaro Takahashi, Susumu Inoue, Kiyomoto Ichiki, Shigehiro Nagataki

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

More than a dozen blazars are known to be emitters of multi-TeV gamma rays, often with strong and rapid flaring activity. By interacting with photons of the cosmic microwave and infrared backgrounds, these gamma rays inevitably produce electron-positron pairs, which in turn radiate secondary inverse Compton gamma rays in the GeV-TeV range with a characteristic time delay that depends on the properties of the intergalactic magnetic field (IGMF). For sufficiently weak IGMF, such "pair echo" emission may be detectable by the Gamma-ray Large Area Space Telescope (GLAST), providing valuable information on the IGMF. We perform detailed calculations of the time-dependent spectra of pair echoes from flaring TeV blazars such as Mrk 501 and PKS 2155-304, taking proper account of the echo geometry and other crucial effects. In some cases, the presence of a weak but nonzero IGMF may enhance the detectability of echo. We discuss the quantitative constraints that can be imposed on the IGMF from GLAST observations, including the case of nondetections.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume686
Issue number2 PART 2
DOIs
StatePublished - Jan 1 2008

Fingerprint

blazars
echoes
magnetic field
Fermi Gamma-ray Space Telescope
magnetic fields
gamma rays
electron-positron pairs
emitters
time lag
microwaves
geometry
electron
photons

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Murase, Kohta ; Takahashi, Keitaro ; Inoue, Susumu ; Ichiki, Kiyomoto ; Nagataki, Shigehiro. / Probing intergalactic magnetic fields in the glast era through pair echo emission from TeV blazars. In: Astrophysical Journal. 2008 ; Vol. 686, No. 2 PART 2.
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Probing intergalactic magnetic fields in the glast era through pair echo emission from TeV blazars. / Murase, Kohta; Takahashi, Keitaro; Inoue, Susumu; Ichiki, Kiyomoto; Nagataki, Shigehiro.

In: Astrophysical Journal, Vol. 686, No. 2 PART 2, 01.01.2008.

Research output: Contribution to journalArticle

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