A Strategy for Identifying Periodic Sources Contributing to the Galactic Center Excess

TL;DR

This paper proposes a method to detect periodic signals from millisecond pulsars in gamma-ray data, which could confirm their role in the Galactic Center excess, distinguishing them from dark matter annihilation.

Contribution

It introduces a novel approach to identify periodic MSP signals in gamma-ray data, providing a potential definitive test for their contribution to the excess.

Findings

Potential to detect MSP periodicity in Fermi data

Robustness against timing perturbations

Supports MSP hypothesis for Galactic Center excess

Abstract

The origin of the Galactic Center gamma-ray excess has not been conclusively determined after over a decade of careful study. The two most widely discussed possibilities are a population of millisecond pulsars (MSPs), and annihilation of dark matter particles. In contrast with annihilating dark matter, MSPs are expected to produce periodic emission. We show that even though the number of photons contributing to the excess is small, there is potentially sufficient information in the data from Fermi to detect a periodic MSP signal. Such a detection would definitively prove that at least some fraction of the excess is due to MSPs. We argue that this conclusion is robust to potential timing perturbations of the gamma-ray photons, such as those due to Earth's orbit, even if the number of parameters that must be used to model the perturbations is $\sim 7$.