On discrepancy between ATIC and Fermi data

TL;DR

This paper compares ATIC and Fermi-LAT cosmic ray data fits with PAMELA, highlighting discrepancies such as the narrow ATIC bump versus the smooth Fermi spectrum, and discusses possible dark matter or pulsar origins.

Contribution

It demonstrates that both datasets can be fitted with similar models but reveal conflicting spectral features, emphasizing the discrepancy between ATIC and Fermi data.

Findings

ATIC shows a narrow bump between 300-600 GeV

Fermi spectrum is smooth without a bump

Both datasets can be fitted with similar background and source models

Abstract

Either ATIC or Fermi-LAT data can be fitted together with the PAMELA data by three components: primary background ~ E^{-3.3}, secondary background ~ E^{-3.6}, and an additional source of electrons ~ E^{-g_a} Exp(-E/E_{cut}). We find that the best fits for ATIC + PAMELA and for Fermi + PAMELA are approximately the same, g_a ~ 2 and E_{cut} ~ 500 GeV. However, the ATIC data have a narrow bump between 300 GeV and 600 GeV which contradicts the smooth Fermi spectrum. An interpretation of the ATIC bump as well as the featureless Fermi spectrum in terms of dark matter models and pulsars is discussed.