The persistent stream of gamma radiation emanating from the central region of the Milky Way has once again captured the attention of the scientific community following a recent study published on October 16, 2025. This long-standing cosmic mystery, formally recognized as the Galactic Center Excess (GCE), remains a highly contentious topic. Currently, two primary hypotheses dominate the discussion regarding its origin: either the emission is a byproduct of the annihilation of dark matter particles, or it represents the collective glow produced by a vast population of millisecond pulsars.
Researchers recently leveraged the immense processing power of supercomputers to generate intricate models mapping the hypothesized distribution of dark matter within our galaxy, basing these simulations on its known formation history. The resulting gamma-ray signal maps derived from these computational models showed a striking correspondence with observational data collected by the Fermi space telescope. This notable alignment strongly suggests a potential link between the observed radiation and processes involving dark matter, which is estimated to constitute approximately a quarter of the total mass-energy content of the Universe. Nevertheless, some scientists maintain that the alternative explanation, involving millisecond pulsars—rapidly spinning remnants of supernovae—remains a viable contender.
For the millisecond pulsar theory to adequately explain the observed GCE pattern, scientists must postulate the existence of a significantly greater number of these objects than have been detected to date. This requirement introduces a substantial challenge to prevailing models of stellar evolution, casting doubt on current understanding. The divergence between the two leading theories underscores that while both remain plausible, a definitive resolution necessitates further, more intensive investigation. Determining the true source of this mysterious emission is paramount, as it holds the key to understanding the fundamental nature of dark matter—an essential, yet still unobserved, component of the cosmos.
The scientific community anticipates a major breakthrough with the expected commissioning of data from the Cherenkov Telescope Array (CTA) in 2026. This international project, designed as the next-generation observatory for studying high-energy gamma radiation, is poised to settle this long-running astrophysical dispute. The CTA Organization (CTAO) was formally established as a European Consortium for Research Infrastructure in January 2025.
The CTA will comprise two distinct arrays. The northern array, situated on the island of La Palma, will primarily focus on extragalactic objects. Conversely, the southern array, located in the Atacama Desert in Chile, is designed to cover the full energy spectrum and concentrate on galactic sources, including the GCE. Overall, the CTA project promises to deliver a sensitivity improvement of an order of magnitude compared to its predecessors, such as MAGIC, H.E.S.S., and VERITAS, offering unprecedented clarity in the search for the origin of the Galactic Center Excess.