ESA/Gaia/DPA, T. Donlon et al.; Stefan Payne-Wardenar
The Milky Way and its surrounding “halo” of stars
Researchers have identified what could be a compelling clue in the ongoing hunt to prove the existence of dark matter.
One mysterious diffuse glow of gamma rays near the center of the Milky Way has perplexed researchers for decades as they tried to discern whether the light comes from colliding dark matter particles or rapidly rotating neutron stars.
It turns out that both theories they are equally likelyaccording to a new magazine published last week Physical Review Letters.
If the excess gamma rays are not coming from dying stars, it could become the first evidence that dark matter exists.
“Dark matter dominates the Universe and holds the galaxies together. It is extremely important and we are always desperately thinking of ideas to detect it”, he says Joseph Silkprofessor of physics and astronomy at Johns Hopkins University and researcher at the Institute of Astrophysics at Sorbonne University.
“Gamma rays, and specifically the excess light we are seeing at the center of our Galaxy, could be our first clue,” adds Silk, co-author of the recently published study.
Silk and an international team of researchers, led by Moorits Murufrom the Leibniz Institute for Astrophysics in Potsdam, used supercomputers to create maps of the location of dark matter in the Milky Waytaking into account, for the first time, the history of the formation of the Galaxy.
Currently, the Milky Way It is a relatively closed systemwith no materials entering or leaving it. But it wasn’t always like that.
During the first billion years, many smaller galaxy-like systems, made of dark matter and other materialsentered and became the building blocks of the young Milky Way.
As dark matter particles gravitated toward the center of the Galaxy and clumped together, the number of dark matter collisions increased.
When researchers considered more realistic collisionsthe simulated maps matched the real gamma-ray maps obtained by the Fermi Gamma-ray Space Telescope.
These concordant maps complete a triad of evidence which suggest that excess gamma rays in the galaxy may originate from dark matter.
Gamma rays from collisions of dark matter particles would produce the same sign and would have the same properties than those observed in the real world, researchers said – although it is not definitive proof.
The light emitted by old, reinvigorated, rapidly rotating neutron stars – so-called millisecond pulsars – could also explain the existing gamma ray map, measurements and signal signature.
But researchers consider this theory of millisecond pulsars to be imperfect. For these calculations to workresearchers must assume that there are more millisecond pulsars than those who observed.
The answers could come with the construction of a huge new gamma-ray telescope CTAO (Cherenkov Telescope Array Observatory). Researchers think that data from the higher-resolution telescope, which has the ability to measure high-energy signals, will help astrophysicists break the paradox.
The research team is now planning a new experiment to test whether these gamma rays from the Milky Way have higher energiesmeaning they are millisecond pulsars, or whether they are the lower-energy product of dark matter collisions.
“A clean signal would be the ultimate proof“, says Silk. “It is possible that we will see the new data and confirm one theory over the other. Or maybe we won’t find anything, in which case It will be an even bigger mystery to solve“.
