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±1.8  GeV compared to the lower-energy, power-law trend, (b) a sharp dropoff above 284+91−64  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 of Es=810+310−180  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.

Towards Understanding the Origin of Cosmic-Ray Positrons

Bertucci, B.
Writing – Review & Editing
;
Burger, W. J.
Membro del Collaboration Group
;
CASTELLINI, GIULIO
Membro del Collaboration Group
;
Donnini, F.
Membro del Collaboration Group
;
Fiandrini, E.
Membro del Collaboration Group
;
Graziani, M.
Membro del Collaboration Group
;
Laudi, E.
Membro del Collaboration Group
;
Mussolin, L.
Membro del Collaboration Group
;
Oliva, A.
Membro del Collaboration Group
;
Pauluzzi, M.
Membro del Collaboration Group
;
Tomassetti, N.
Membro del Collaboration Group
;
Vagelli, V.
Writing – Review & Editing
;
2019

Abstract

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±1.8  GeV compared to the lower-energy, power-law trend, (b) a sharp dropoff above 284+91−64  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 of Es=810+310−180  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.
2019
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1448034
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