10-17 July 2019
Europe/Brussels timezone

Towards Understanding the Origin of Cosmic-Ray Positrons

11 Jul 2019, 09:45
Campus Ledeganck - Aud. 2 (Ghent)

Campus Ledeganck - Aud. 2


Parallel talk Dark Matter Dark Matter


Nikolas Zimmermann (Rheinisch Westfaelische Tech. Hoch. (DE))


Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million positrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties are: (a) a significant excess starting from 25.2 GeV compared to the lower-energy, power-law trend; (b) a sharp drop-off above 284 GeV; (c) in the entire energy range the positron flux is well described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which dominates at low energies, and a new source term of positrons, which dominates at high energies; and (d) a finite energy cutoff of the source term at 810 GeV is established with a significance of more than 4σ. These experimental data on cosmic ray positrons show that, at high energies, they predominantly originate either from dark matter annihilation or from other astrophysical sources.

Primary authors

Zhili Weng (Massachusetts Inst. of Technology (US)) Matteo Duranti (Universita e INFN, Perugia (IT)) Weiwei Xu (Massachusetts Inst. of Technology (US)) Zuhao Li (Chinese Academy of Sciences (CN)) Andrei Kounine (Massachusetts Inst. of Technology (US)) Nikolas Zimmermann (Rheinisch Westfaelische Tech. Hoch. (DE))

Presentation Materials