The study suggests that the Milky Way shows an increase in gamma rays due to the annihilation of dark matter

New research shows that dark matter has a different distribution in our Galaxy than previously thought, and this strengthens dark matter’s position as a potential source of the excess gamma rays observed at the center of the Milky Way. High-resolution simulations reveal that the distribution of dark matter in the inner galaxy is not spherical, but flat and asymmetric. The results confirm the theory that the gamma ray excess is due to the annihilation of dark matter.

Scientists have long suspected that dark matter annihilation was the source of these rays, but the spatial spread of the rays did not match the dark matter arrangement they expected. Another theory says that millisecond-old pulsars could produce the rays.

For the new study published in Physical review lettersthe researchers modeled the formation of Milky Way-like galaxies under environmental conditions similar to those in Earth’s cosmic neighborhood, thus reproducing Milky Way-like galaxies that bear a strong resemblance to real galaxies.

They found that dark matter does not radiate outward from the galactic center, but is instead organized similarly to that in stars, meaning the former can produce just as much excess gamma rays.

“When the FERMI space telescope pointed at the center of the galaxy, the results were astonishing. The telescope measured a very large number of gamma rays, the most energetic type of light in the universe. Astronomers around the world were puzzled, and competing theories began to pour in to explain the so-called ‘gamma-ray excess,’” says Noam Libeskind of the Leibniz Institute for Astrophysics. Potsdam (AIP).

After much debate, two ideas came to the fore: either these gamma rays were the result of millisecond pulsars (ultra-dense neutron stars that spin thousands of times per second) or from dark matter particles colliding with each other and destroying them. Both theories have their drawbacks. However, new findings presented by scientists at AIP in collaboration with the Hebrew University in Israel and Johns Hopkins University in the United States have shed new light on this problem, effectively confirming the theory that the gamma ray excess is due to the annihilation of dark matter.

It has long been known that the Milky Way Galaxy lives in a so-called dark matter halo, a spherical region filled with dark matter around it. However, the extent to which this halo is nearly spherical or elliptical has not been estimated.

“We have analyzed simulations of the Milky Way and its dark matter halo and found that the flatness of this region is sufficient to explain the gamma-ray excess as being caused by self-annihilating dark matter particles,” says Maurits Moreau, lead author of the study. “These calculations show that the search for dark matter particles (that can self-annihilate) should be encouraged and bring us one step closer to understanding the mysterious nature of these Particles.