Emissions from a population of 100,000 spinning neutron stars at the center of the Milky Way could explain the origin of a mysterious gamma-ray signal from that part of the galaxy, long associated with enigmatic dark matter. The signal, called the Galactic Central Excess, is an unexpected concentration of gamma rays emerging from the center of our galaxy that has baffled astronomers.
An international team of astronomers led by the Australian National University (ANU) has concluded that the strange emissions of Gamma rays emanating from the heart of the Milky Way are not a manifestation of the elusive and hitherto unexplained dark matter, but a phenomenon generated by an enormous number of spinning neutron stars, also called millisecond pulsars.
According to a press release, a “community & rdquor; from about 100,000 of these neutron stars would be responsible for the mysterious gamma-ray emissions, baptized by scientists as the Galactic Center Excess (GCE, according to the acronym in English). Until now, this great flow of energy detected in the galactic center had been considered by specialists as a “signature & rdquor; of dark matter, an unknown type of matter that would concentrate approximately 80% of the existing matter in the Universe.
the highest energy
The gamma rays they are the form of electromagnetic radiation with the shortest wavelength and the highest energy. Although it was already known that emissions of this type can be recorded in the center of the Milky Way, previous research has identified an unusual amount of gamma rays, the origin of which has not been explained until today. However, some studies have linked them to dark matter.
Now, new research recently published in the journal Nature Astronomy comes to another kind of conclusion. The team of scientists led by Anuj Gautam believes that the Galactic Center Excess it is the product of gigantic emissions generated by millisecond pulsars, a specific type of neutron star that rotates rapidly, specifically at around 100 times per second.
Are spinning neutron stars they hatch from the super-dense stellar remnants of other stars more massive than our Sun. Astronomers have previously detected gamma-ray emissions from individual millisecond pulsars within the Solar System, so it was already known that these objects can produce gamma rays .
However, the model created in the framework of the new study shows that the integrated emission of a population of about 100,000 rotating neutron stars or millisecond pulsars it could produce a colossal gamma-ray signal, fully compatible in magnitude with the Galactic Central Excess.
“Fog” of microwave
Apparently, it would not be an isolated case: the Andromeda gamma-ray signal, the closest large galaxy to the Milky Way, could also be produced by the activity of millisecond pulsars. At the same time, scientists believe that emissions from spinning neutron stars could simultaneously explain the mysterious microwave “haze” detected in the interior of the galaxy.
In 2012, scientists detected this strange haze using the European Space Agency’s (ESA) Planck space observatory. The enigmatic fog, not to be confused with the so-called cosmic microwave background, is shown as a diffuse emission coming from the region surrounding the central part of the galaxy. An explanation for this phenomenon has not yet been found, but the new study could shed light on its origin.
Reference
Millisecond pulsars from accretion-induced collapse as the origin of the Galactic Center gamma-ray excess signal. Anuj Gautam, Roland M. Crocker, Lilia Ferrario, Ashley J. Ruiter, Harrison Ploeg, Chris Gordon, and Oscar Macias. Nature Astronomy (2022). DOI:https://doi.org/10.1038/s41550-022-01658-3