The century-old thriller of darkish matter — the invisible glue thought to carry galaxies collectively — simply bought a contemporary clue.
Scientists say they could be one step nearer to confirming the existence of this elusive materials, because of new simulations suggesting {that a} faint glow on the middle of the Milky Method could possibly be darkish matter’s long-sought signature.
The findings, show that dark matter near the Milky Way’s center might not form a perfect sphere as scientists long thought. Instead, it appears flattened, almost egg-shaped, and that shape closely mirrors the pattern of mysterious gamma rays observed by NASA’s Fermi Gamma-ray Space Telescope.
This builds on research dating back to 2008, when Fermi first spotted a broad, hazy glow of high-energy light near the galactic core, stretching across some 7,000 light-years. The signal was far brighter than existing models could explain.
Some scientists proposed that these rays could be the by-product of invisible dark matter particles known as WIMPs (short for weakly interacting massive particles) colliding and annihilating one another. Others argued they came from fast-spinning stellar remnants known as millisecond pulsars — ancient, rapidly spinning neutron stars that emit beams of radiation like cosmic lighthouses.
The pulsar theory made sense because the gamma-ray glow appeared flattened and bulging, much like the Milky Way’s star-filled central region. If dark matter were behind the glow, scientists had expected a smoother, rounder pattern.
Muru and his team decided to put both ideas to the test. Using powerful supercomputers, they recreated how the Milky Way formed, including billions of years of violent collisions and mergers with smaller galaxies. Those violent events, the researchers found, left deep “fingerprints” on the way dark matter is distributed in the galactic core.
When this complex history is factored in, the simulated dark matter halo no longer looks spherical. Instead, it takes on a flattened, egg-like form — matching the pattern of gamma-ray emission Fermi has observed, the new study reports.
“We’re showing that dark matter also has this flattened shape,” Muru said. “So, it does match the [gamma ray] excess much better than expected before.”
The finding suggests that dark matter could still be a strong contender behind the Milky Way’s mysterious glow. But it doesn’t completely rule out pulsars, the researchers say. Both possibilities, the team concludes, are now “essentially indistinguishable.”
If the excess truly arises from dark matter collisions, it would mark the first indirect evidence that WIMPs, a leading dark matter candidate, really exist.
Definitive answers could come by the late 2020s, when the Cherenkov Telescope Array Observatory (CTAO) begins scanning the skies from its twin websites in Chile and Spain. The ability will be capable of observe gamma rays at a lot larger decision than Fermi, researchers say, doubtlessly serving to them distinguish between a swarm of pulsars, which have larger energies, and lower-energy annihilating darkish matter particles.
Muru added that gamma-ray observations of smaller dwarf galaxies orbiting the Milky Method, whose cores additionally host darkish matter in dense pockets, may additional check each prospects.
“That is the place we hope to measure the sign,” mentioned Muru. “We’re actually wanting ahead to those observations.”
Scientists are satisfied darkish matter is on the market. The hunt to detect it arguably stays each some of the irritating and most exhilarating challenges in trendy physics.
“For some motive, it nonetheless eludes us,” Muru mentioned. “And I believe the thriller makes it much more fascinating.”
The outcomes have been detailed in a paper printed Oct. 16 within the journal Bodily Assessment Letters.
