# A self-consistent model of cosmic-ray fluxes and positron excess: Roles of nearby pulsars and a sub-dominant source population

## TL;DR

This paper presents a self-consistent model combining nearby pulsars and a secondary source population to explain the cosmic-ray positron excess observed above 10 GeV, fitting multiple cosmic-ray flux data sets.

## Contribution

It introduces a comprehensive model that accounts for the positron excess by including both pulsar contributions and a sub-dominant source population, using the DRAGON propagation code.

## Key findings

- Nearby pulsars significantly contribute to the positron excess.
- The model fits AMS data for positrons, electrons, protons, and helium.
- The diffusion spectral index is close to Kraichnan turbulence value.

## Abstract

The cosmic-ray positron flux calculated using the cosmic-ray nuclei interactions in our Galaxy cannot explain observed data above 10 GeV. An excess in the measured positron flux is therefore open to interpretation. Nearby pulsars, located within sub-kiloparsec range of the Solar system, are often invoked as plausible sources contributing to the excess. We show that an additional, sub-dominant population of sources together with the contributions from a few nearby pulsars can explain the latest positron excess data from the Alpha Magnetic Spectrometer (AMS). We simultaneously model, using the DRAGON code, propagation of cosmic-ray proton, Helium, electron and positron and fit their respective flux data. Our fit to the Boron to Carbon ratio data gives a diffusion spectral index of 0.45, which is close to the Kraichnan turbulent spectrum.