Universal upper limit on inflation energy scale from cosmic magnetic field

Tomohiro Fujita*, Shinji Mukohyama

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)


Recently observational lower bounds on the strength of cosmic magnetic fields were reported, based on γ-ray flux from distant blazars. If inflation is responsible for the generation of such magnetic fields then the inflation energy scale is bounded from above as ρ inf 1/4 < 2.5 × 10 -7M Pl × (B obs/10 -15G) -2 in a wide class of inflationary magnetogenesis models, where B obs is the observed strength of cosmic magnetic fields. The tensor-to-scalar ratio is correspondingly constrained as r < 10 -19 × (B obs/10 -15G) -8. Therefore, if the reported strength B obs 10 -15G is confirmed and if any signatures of gravitational waves from inflation are detected in the near future, then our result indicates some tensions between inflationary magnetogenesis and observations.

Original languageEnglish
Article number034
JournalJournal of Cosmology and Astroparticle Physics
Issue number10
Publication statusPublished - 2012 Oct
Externally publishedYes


  • extragalactic magnetic fields
  • inflation
  • primordial gravitational waves (theory)
  • primordial magnetic fields

ASJC Scopus subject areas

  • Astronomy and Astrophysics


Dive into the research topics of 'Universal upper limit on inflation energy scale from cosmic magnetic field'. Together they form a unique fingerprint.

Cite this