Connecting the new H.E.S.S. diffuse emission at the Galactic center with the Fermi GeV excess: a combination of millisecond pulsars and heavy dark matter?

TL;DR

This paper proposes a leptonic model combining millisecond pulsars and heavy dark matter annihilation to explain the gamma-ray emission from the Galactic center, connecting Fermi-LAT and H.E.S.S. observations.

Contribution

It introduces a novel leptonic scenario linking the GeV excess and TeV emission through pulsars and dark matter, contrasting with previous hadronic models.

Findings

Model reproduces the spectral morphology of H.E.S.S. emission.

Dark matter component matches the spatial distribution above 10 TeV.

Pulsar contribution predicts an extended emission at lower energies.

Abstract

The H.E.S.S. collaboration has reported a high-energy spherically symmetric diffuse gamma-ray emission in the inner 50 pc of the Milky Way, up to ~ 50 TeV. Here we propose a leptonic model which provides an alternative to the hadronic scenario presented by the H.E.S.S. collaboration, and connects the newly reported TeV emission to the Fermi-LAT Galactic center GeV excess. Our model relies on a combination of inverse Compton emission from a population of millisecond pulsars---which can account for the GeV excess---and a supermassive black hole-induced spike of heavy (~ 60 TeV) dark matter particles annihilating into electrons with a sub-thermal cross-section. With an up-to-date interstellar radiation field, as well as a standard magnetic field and diffusion set-up, our model accounts for the spectral morphology of the detected emission. Moreover, we show that the dark matter induced emission reproduces the spatial morphology of the H.E.S.S. signal above ~ 10 TeV, while we obtain a slightly more extended component from pulsars at lower energies, which could be used as a prediction for future H.E.S.S. observations.