For decades, astronomers have been puzzled by a mysterious glow of gamma rays emanating from near the center of the Milky Way. Two theories have emerged: either the light was the result of dark matter particles colliding, or it’s coming from rapidly spinning neutron stars — the extremely dense remains of exploded stars — called pulsars.

Now, a new paper published in the journal Physical Review Letters might not have a satisfying answer — it argues that both theories are equally likely — but it does raise the stakes: if the first possibility turns out to be correct, it could be the first-ever concrete evidence that dark matter, the mysterious stuff that is believed to make up more than 26 percent of the universe, actually exists.

“Dark matter dominates the universe and holds galaxies toge

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