Multi-messenger constraints to the local emission of cosmic-ray electrons

Abstract

The data on the inclusive flux of cosmic positrons and electrons (e + + e − ) have been recently collected from GeV to tens of TeV energies by several experiments with unprecedented precision. In addition, the Fermi-LAT Collaboration has provided a new energy spectrum for the upper bounds on the e + + e − dipole anisotropy. This observable can bring information on the emission from local Galactic sources, notably measured with high precision at radio frequencies. We develop a framework in which e − and e + measured at Earth from GeV up to tens of TeV energies have a composite origin. A dedicated analysis is deserved to Vela YZ and Cygnus Loop Supernova Remnants (SNRs), for which we consider two different models for the injection of e − . We investigate the consistency of these models using the three physical observables: the radio flux from Vela YZ and Cygnus Loop at all the available frequencies, the e + + e − flux from five experiments from the GeV to tens of TeV energy, the e + + e − dipole anisotropy upper limits from 50 GeV to about 1 TeV. We find that the radio flux for these nearby SNRs strongly constraints the properties of the injection electron spectrum, partially compatible with the looser constraints derived from the e + + e − flux data. We also perform a multi-wavelength multi-messenger analysis by fitting simultaneously the radio flux on Vela YZ and Cygnus Loop and the e + +e − flux, and checking the outputs against the e + + e − dipole anisotropy data. Remarkably, we find a model which is compatible with all the e + + e − flux data, the radio data for Vela YZ and Cygnus Loop, and with the anisotropy upper bounds. We show the severe constraints imposed by the most recent data on the e + + e − dipole anisotropy.

Galactic halo size in the light of recent AMS-02 data

“…In the last decade, antimatter data received a lot of scrutiny, owing to the interpretation of the positron fraction rise as a DM signal (Adriani et al 2009;Bergström et al 2008;Feng & Zhang 2018), although standard astrophysics explanations are more likely (e.g. Hooper et al 2009;Delahaye et al 2010;Serpico 2012;Manconi et al 2019). Similarly, the presence of a DM contribution in the p data is debated in the literature (Reinert & Winkler 2018;Cholis et al 2019;Cuoco et al 2019;Boudaud et al 2020).…”

Multi-messenger constraints to the local emission of cosmic-ray electrons

“…[14]. We present here a multi-component model that explains the e + and e − + e + fluxes from five experiments and in a wide energy range, and that is simultaneously compatible with the upper bounds on the dipole anisotropy and the radio emission from the most intense and closest SNRs [15].…”

Galactic Cosmic Rays Anomalies

“…As visible in Fig. 1, leptonic data can be interpreted with the emission of electrons and positrons from Supernova Remnants, Pulsar Wind Nebulae and the secondary production [13]. The anisotropy data are now close, or even lower than theoretical models.…”

“…A viable explanation of the experimental result resides in the additional contribution of astrophysical sources accelerating leptons in their sites. The cosmic fluxes of positrons and leptons are quite sensitive to the presence of sources in the near Galaxy (few kpc), whose physics can be explored also in this peculiar channel [13] (and refs. therein).…”

“…Recently, the lepton data have also been analyzed in terms of their arrival direction [14,13]. Upper limits on the dipole anisotropy ∆ have been set for the electron plus positron flux [15].…”