Galactic Center’s Gamma-Ray Mystery Deepens as Dark Matter and Pulsars Compete for Explanation

The Galactic Center’s Enigmatic Glow

For over a decade, astronomers have been captivated by a mysterious gamma-ray signal emanating from the heart of our Milky Way. Known as the Galactic Center GeV Excess (GCE), this unexplained radiation represents one of modern astrophysics’ most compelling puzzles. Recent research now suggests that the long-standing debate between two competing explanations—dark matter annihilation versus millisecond pulsars—may be more complex than previously thought, with both scenarios appearing equally plausible based on current evidence.

Dark Matter’s Potential Signature

The dark matter hypothesis represents one of the most exciting possibilities for explaining the GCE. Dark matter constitutes approximately 85% of all matter in the universe, yet it remains invisible to direct detection. According to Dr. Joseph Silk of Johns Hopkins University, “Gamma rays, and specifically the excess light we’re observing at the center of our galaxy, could be our first clue” to understanding this mysterious component of our cosmos.

The leading theoretical candidate for dark matter consists of Weakly Interacting Massive Particles (WIMPs). When these hypothetical particles collide with their antiparticles, they would annihilate each other in spectacular explosions that produce gamma-ray photons among other particles. This process could potentially generate the exact type of radiation excess observed at the galactic center., according to industry developments

The Pulsar Alternative

The competing explanation points to millisecond pulsars—rapidly spinning neutron stars that represent the final evolutionary stage of massive stars. These cosmic lighthouses emit beams of radiation, including gamma rays, as they rotate. A population of such pulsars in the galactic bulge could collectively produce the observed gamma-ray excess, though astronomers have yet to directly detect the specific pulsars responsible for the GCE., according to market insights

Previous research had suggested that the spatial distribution of the GCE might favor the pulsar explanation. The expected spherical shape of dark matter halos seemed inconsistent with the somewhat boxy distribution observed in Fermi telescope data, while the distribution of old stars that would host pulsars appeared to match this boxy pattern more closely.

New Simulations Challenge Assumptions

A groundbreaking study led by cosmologist Moorits Mihkel Muru from the Leibniz Institute for Astrophysics Potsdam has dramatically reshaped this debate. Using sophisticated supercomputer simulations of Milky Way-like galaxies, the research team mapped the evolutionary history of dark matter distribution, comparing it with the distribution of old stars that serve as proxies for millisecond pulsars.

The simulations revealed that the Milky Way’s dark matter halo isn’t perfectly spherical but has become slightly flattened over billions of years due to gravitational interactions and mergers with other galaxies. When viewed from our solar system’s position approximately 8 kiloparsecs from the galactic center, this flattened dark matter distribution produces a gamma-ray glow that appears boxy—precisely the characteristic previously thought to favor pulsars., according to related coverage

Equally Plausible Explanations

The research team concluded that both hypotheses now stand on equal footing. As they note in their paper, “Both hypotheses for the GCE, that of dark matter annihilations and millisecond pulsars, are equally plausible based on morphology, spectrum, and intensity, with perhaps a slight edge for the dark matter hypothesis.” This slight advantage comes from the observed deficiency in detected millisecond pulsars that would be needed to explain the full intensity of the GCE.

However, the puzzle contains additional complexity. Some observations have detected slight speckling in the GCE, consistent with what would be expected from point sources like individual pulsars. Dark matter annihilation would typically produce a smoother, more uniform glow. This small-scale texture hasn’t been directly addressed in the current study but suggests the possibility that both mechanisms might be contributing to the observed signal.

The Path Forward

The scientific community now looks toward next-generation observatories to break the deadlock. Upcoming facilities including the Cherenkov Telescope Array and the Southern Wide-field Gamma-ray Observatory promise unprecedented sensitivity that should help distinguish between the competing scenarios., as related article

As Dr. Silk notes, “It’s possible we will see the new data and confirm one theory over the other. Or maybe we’ll find nothing, in which case it’ll be an even greater mystery to resolve.” The resolution of this mystery could either provide the first direct evidence for dark matter particles or reveal new insights about the population and behavior of millisecond pulsars in our galaxy’s core.

What remains clear is that the galactic center continues to be one of the most dynamic and mysterious regions of our galaxy, holding secrets that could fundamentally reshape our understanding of the universe’s most basic constituents.

References & Further Reading

This article draws from multiple authoritative sources. For more information, please consult:

• https://hub.jhu.edu/2025/10/16/mysterious-glow-in-milky-way-dark-matter/
• https://doi.org/10.48550/arXiv.0910.2998
• https://www.jpl.nasa.gov/spaceimages/details.php?id=pia20699
• https://doi.org/10.1088/0954-3899/41/6/063101
• https://scipost.org/SciPostPhysProc.12.006/pdf
• https://doi.org/10.1103/g9qz-h8wd
• https://doi.org/10.1103/PhysRevD.101.023014

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