We present a novel calculation of the spectrum of electrons and positrons from random sources, supernova remnants and pulsars, distributed within the spiral arms of the Galaxy. The pulsar emissivity in terms of electron-positron pairs is considered as time dependent, following the magnetic dipole spin-down luminosity, and the temporal evolution of the potential drop is accounted for. Moreover each pulsar, with the magnetic field and initial spin period selected at random from the observed distribution, is considered as a source of pairs only after it leaves the parent supernova due to its birth kick velocity (also selected at random from the observed distribution). We show that (i) the spectrum of electrons is characterized by a feature at ≤gamma;50 GeV that proves that their transport is dominated by radiative losses. The flux reduction at E≤gamma;1 TeV is explained as a result of lepton transport from sources in the spiral arms. (ii) The spectrum of positrons is very well described by the contribution of pulsars and the rising positron fraction originates naturally. The implications of pulsars as positron sources in terms of positron fraction at very high energies are also discussed. (iii) The role of fluctuations in the high-energy regime is thoroughly discussed and used to draw conclusions on the possibility to single out the contribution of local sources to the lepton spectrum with current and upcoming experiments

Galactic factories of cosmic-ray electrons and positrons

Evoli, Carmelo
;
Blasi, Pasquale;Aloisio, Roberto
2021-01-01

Abstract

We present a novel calculation of the spectrum of electrons and positrons from random sources, supernova remnants and pulsars, distributed within the spiral arms of the Galaxy. The pulsar emissivity in terms of electron-positron pairs is considered as time dependent, following the magnetic dipole spin-down luminosity, and the temporal evolution of the potential drop is accounted for. Moreover each pulsar, with the magnetic field and initial spin period selected at random from the observed distribution, is considered as a source of pairs only after it leaves the parent supernova due to its birth kick velocity (also selected at random from the observed distribution). We show that (i) the spectrum of electrons is characterized by a feature at ≤gamma;50 GeV that proves that their transport is dominated by radiative losses. The flux reduction at E≤gamma;1 TeV is explained as a result of lepton transport from sources in the spiral arms. (ii) The spectrum of positrons is very well described by the contribution of pulsars and the rising positron fraction originates naturally. The implications of pulsars as positron sources in terms of positron fraction at very high energies are also discussed. (iii) The role of fluctuations in the high-energy regime is thoroughly discussed and used to draw conclusions on the possibility to single out the contribution of local sources to the lepton spectrum with current and upcoming experiments
2021
Positron; Dark Matter; Particle Astrophysics, Cosmic ray composition & spectra, Cosmic ray propagation, Cosmic ray sources, Cosmic rays & astroparticles
File in questo prodotto:
File Dimensione Formato  
PhysRevD.103.083010-accepted_2.pdf

accesso aperto

Tipologia: Documento in Post-print
Licenza: Creative commons
Dimensione 10.48 MB
Formato Adobe PDF
10.48 MB Adobe PDF Visualizza/Apri
PostPrint_2021_PhysRevD_103_083010_Evoli.pdf

accesso aperto

Tipologia: Documento in Post-print
Licenza: Creative commons
Dimensione 8.5 MB
Formato Adobe PDF
8.5 MB Adobe PDF Visualizza/Apri
2021_PhysRevD_103_083010_Evoli.pdf

non disponibili

Tipologia: Versione Editoriale (PDF)
Licenza: Non pubblico
Dimensione 5.38 MB
Formato Adobe PDF
5.38 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12571/21961
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 52
  • ???jsp.display-item.citation.isi??? 47
social impact