Intergalactic magnetic field spectra from diffuse gamma-rays

Wenlei Chen, Borun D. Chowdhury, Francesc Ferrer, Hiroyuki Tashiro, Tanmay Vachaspati

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Non-vanishing parity-odd correlators of gamma-ray arrival directions observed by Fermi-LAT indicate the existence of a helical intergalactic magnetic field with strength B ~ 10-14 G on ~10 Mpc scales. We successfully test this hypothesis using more stringent cuts of the data, Monte Carlo simulations with Fermi-LAT time exposure information, separate analyses for the Northern and Southern galactic hemispheres, and confirm predictions made in Tashiro & Vachaspati. With some further technical assumptions, we show how to reconstruct the magnetic helicity spectrum from the parity-odd correlators.

Original languageEnglish (US)
Pages (from-to)3371-3380
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Apr 24 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 The Author.


  • Cosmology: observations
  • Early universe
  • Gamma-rays: diffuse background


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