Inverse Compton emission from Heavy WIMP annihilations in the Galactic Centre

Abstract

A thermal relic Weakly Interacting Massive Particle (WIMP) remains one of the most well-motivated dark matter candidates. Many indirect search experiments aim to detect photon signals from WIMP annihilations, with the Milky Way’s Galactic Centre being a prime target. In this work, we extend a previous study that highlighted the significance of sec ondary emission, particularly inverse Compton radiation. This radiation is expected by radiative cooling of the electrons produced in WIMP annihilation, but is frequently ignored by indirect searches. In the first part of the work, we analyse the total emission spectrum, including direct gamma rays, inverse Compton radiation and synchrotron radiation from lesser-constrained heavy WIMPs. In the second part, we develop a more realistic 3D simula tion framework to model WIMPannihilation and its secondary emission output incorporating spatially varying dark matter density profiles, varying external magnetic and radiation fields, as well as electron transport mechanisms such as advection wind and di!usion in the chaotic and intense Galactic Centre region. We examine how these factors influence both the spatial and spectral distribution of the different emissions for different WIMP masses and compare the two simulation approaches. We also comment on the usefulness of our approach for dark matter candidates beyond the classical thermal-relic annihilating WIMP. Our findings provide insights into refining detection strategies and highlight the importance of accounting for secondary emissions for future detection prospects of heavy WIMPs.