The mysterious gamma rays emanating from the galactic center are generated by young neutron stars living in the densest region of the Milky Way's core, not by the decay of dark matter particles. This is the conclusion reached by astrophysicists who published an article in the journal Nature.
“At such a distance, the individual gamma-ray fluxes generated by these dead stars will merge together and form a uniformly distributed signal, similar to that which should occur when dark matter particles decay. This is supported by the fact that millisecond pulsars located near the Earth are considered to be bright sources of gamma rays,”said Roland Crocker of the Australian National University in Canberra.
Dark matter is an invisible substance, the presence of which can only be judged by its gravitational effect, it does not interact with electromagnetic waves, that is, it does not emit, absorb or reflect any radiation. The share of ordinary matter accounts for 4.9% of the mass of the Universe, dark matter - 26.8%. Most physicists today believe that dark matter can be composed of heavy, weakly interacting particles, the so-called "wimps".
In 2009, as it seemed to scientists then, the recently launched Fermi gamma-ray telescope discovered the first traces of dark matter in the form of a mysterious excess of gamma radiation in the center of the Milky Way, the brightness of which in the high-energy part of the spectrum was noticeably higher than theoretically predicted values. As scientists then suggested, the source of this radiation was the decays of the colliding "WIMPs".
From the point of view of astrophysics, it is quite easy to refute this theory - for this it is necessary to show that gamma photons from the center of the Milky Way fly towards us from point light sources, which can be pulsars and other compact objects. Otherwise, if they are generated by decaying dark matter particles, the "excess" radiation will be evenly distributed over the sky.
Crocker and his colleagues found the first evidence in favor of this theory by analyzing the images that the Fermi telescope received over the past several years of observing the center of the Galaxy. Scientists processed them using special statistical algorithms capable of "removing" all non-point sources of gamma waves, and tried to understand what gives rise to all the other flares.
For this, astrophysicists have created several dozen computer models of the galactic nucleus, in which the role of point sources of gamma radiation was played by a variety of objects - pulsars, black holes, ordinary stars and clouds of interstellar gas. By combining these models and comparing the results of their calculations with real photographs from "Fermi", scientists tried to understand which one is closest to the truth.
For example, in gamma-ray photographs of the bulge, the densest part of the Milky Way's core, you can see a peculiar pattern resembling the letter X. This letter, as scientists explain, arose from the unusual distribution of stars in the central part of the Galaxy, the reason for which is not yet clear.
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A similar structure, as the calculations of Australian astrophysicists show, arises in their models if the role of the main source of mysterious gamma radiation is played not by dark matter or ordinary stars, but by the so-called millisecond pulsars living both inside the bulge and beyond. …
This is how astronomers call relatively young neutron stars that have lived no more than 100 million years and have a tremendous rotation speed - they make one revolution around their axis in a few tens or hundreds of milliseconds. When clusters of matter fall on the surface of such pulsars, powerful bursts of gamma rays and other electromagnetic waves occur.
Previously, astronomers believed that such luminaries could not be present in large numbers in the center of the Galaxy due to the venerable age of most of its stars, but the calculations of Crocker and his team suggest otherwise. Scientists hope that further observations of the galactic "cross" and individual pulsars inside it will help us understand how they originated or what caused the older pulsars to "unwind" again.