Time variability of TeV cosmic ray sky map

Rahul Kumar, Noémie Globus, David Eichler, Martin Pohl

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The variation in the intensity of cosmic rays at small angular scales is attributed to the interstellar turbulence in the vicinity of the Solar system. We show that a turbulent origin of the small-scale structures implies that the morphology of the observed cosmic ray intensity skymap varies with our location in the interstellar turbulence. The gyroradius of cosmic rays is shown to be the length scale associated with an observable change in the skymap over a radian angular scale. The extent to which the intensity at a certain angular scale varies is proportional to the change in our location with a maximum change of about the amplitude of intensity variation at that scale in the existing skymap. We suggest that for TeV cosmic rays a measurable variation could occur over a time-scale of a decade due to the Earth's motion through the interstellar medium, if interstellar turbulence persists down to the gyroradius, about 300 μpc for TeV-ish cosmic rays. Observational evidence of the variability, or an absence of it, could provide a useful insight into the physical origin of the small-scale anisotropy.

Original languageEnglish
Pages (from-to)896-900
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 11 Feb 2019


  • Cosmic rays

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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