Polynomial Spectrum of Gamma Ray from Dark Matter

TL;DR

This paper explores the general features of gamma-ray spectra from dark matter, highlighting that polynomial or power-law spectra can mimic gamma line signals across various models, with implications for cosmic ray and neutrino observations.

Contribution

It demonstrates that dark matter decay or annihilation can produce polynomial or power-law gamma-ray spectra, providing a model-independent analysis that broadens understanding of potential signals.

Findings

Gamma-ray spectra from dark matter can have sharp features or polynomial shapes.

Such spectra can mimic gamma line signals in various models.

Results are applicable to cosmic rays and neutrino observations.

Abstract

In this study, we present some general features of gamma-ray spectra from dark matter. We find that the spectrum with sharp features could appear in a wide class of dark matter models and mimic the gamma line signals. If all other physical degrees of freedom are heavy or effectively decoupled, the resulting gamma ray from dark matter decay or annihilation would generally have polynomial-type spectra or power-law with positive index. We illustrate our findings in a model-independent framework with generic kinematic analysis. Similar results can also apply for cosmic ray or neutrino cases.