UHECR mass composition from anisotropy of their arrival directions with the Telescope Array SD

Discussion timeslot (ZOOM-Meeting): 16. July 2021 - 18:00
ZOOM-Meeting URL: https://icrc2021.desy.de/pf_access_abstracts
Corresponding Session: https://icrc2021-venue.desy.de/channel/Presenter-Forum-1-Evening-All-Categories/48

Abstract:
'We propose a new method for the estimation of ultra-high energy cosmic ray (UHECR) mass composition from a distribution of their arrival directions. The method employs a test statistic (TS) based on a characteristic deflection of UHECR events with respect to the distribution of luminous matter in the local Universe modeled with a flux-weighed 2MRS catalog. Making realistic simulations of the mock UHECR sets, we show that this TS is robust to the presence of galactic and non-extreme extra-galactic magnetic fields and sensitive to the mass composition of events in a set. We apply the method to Telescope Array surface detector data for 11 years and derive new independent constraints on fraction of protons and iron in p-Fe mix at E > 10 EeV. At 10 < E < 100 EeV the data favors increase of allowed proton fraction and decrease of allowed iron fraction, while at E > 100 EeV --- pure iron or even more massive composition. This result is in tension with Auger composition model inferred from spectrum-Xmax fit at 3.0 sigma (2.3 sigma) for PT'11 (JF'12) regular GMF model.'

Authors: Mikhail Kuznetsov | for the Telescope Array Collaboration
Collaboration: Telescope Array

Indico-ID: 217
Proceeding URL: https://pos.sissa.it/395/294