Jul 12 – 23, 2021
Europe/Berlin timezone

The UHECR dipole and quadrupole in the latest data from the original Auger and TA surface detectors

Jul 15, 2021, 12:00 PM
1h 30m


Talk CRI | Cosmic Ray Indirect Discussion


Peter Tinyakov (Universite Libre de Bruxelles (ULB))


The sources of ultra-high-energy cosmic rays are still unknown, but assuming standard physics, they are expected to lie within a few hundred megaparsecs from us. Indeed, over cosmological distances cosmic rays lose energy to interactions with background photons, at a rate depending on their mass number and energy and properties of photonuclear interactions and photon backgrounds. The universe is not homogeneous at such scales, hence the distribution of cosmic-ray arrival directions is expected to reflect the inhomogeneities in the distribution of galaxies; the shorter the energy loss lengths, the stronger the expected anisotropies. Galactic and intergalactic magnetic fields can blur and distort the picture, but the magnitudes of the largest-scale anisotropies, namely the dipole and quadrupole moments, are the most robust to their effects. Measuring them with no bias regardless of any higher-order multipoles is not possible except with full-sky coverage. In this work, we achieve this in three energy ranges (approximately 8–16 EeV, 16–32 EeV, and 32– EeV) by combining surface-detector data collected at the Pierre Auger Observatory and the Telescope Array until 2019, before the completion of the upgrades of the arrays with new scintillation detectors. The results will be presented at the conference.


ultra-high energy cosmic rays; dipole and quadrupole anisotropy

Subcategory Experimental Results
other Collaboration Auger
Collaboration Telescope Array

Primary authors

Presentation materials