The Australian National University (ANU) researchers have found an alternative explanation for a mysterious gamma-ray signal coming from the center of the galaxy. It was long claimed as a signature of dark matter.
Gamma-rays are the form of electromagnetic radiation with the shortest wavelength and highest energy. Co-author of the study Associate Professor Roland Crocker said this particular gamma-ray signal may actually come from a specific type of rapidly-rotating neutron star. The super-dense stellar remnants of some stars much more massive than our sun.
The Galactic Center Excess is an unexpected concentration of gamma-rays emerging from the center of our galaxy that has long puzzled astronomers. This work does not throw any doubt on the existence of the signal. But it offers another potential source.
It is based on millisecond pulsars around 100 times a second. Scientists have previously detected gamma-ray emissions from individual millisecond pulsars in the neighborhood of the solar system. We know these objects emit gamma-rays. The model demonstrates that the integrated emission from a whole population of such stars which is around 100,000 in number and would produce a signal entirely compatible with the Galactic Center Excess.
The discovery may mean scientists have to re-think where they look for clues about dark matter. The nature of dark matter is totally unknown. So, any potential clues garner a lot of excitement. But the results point to another important source of gamma-ray production. The gamma-ray signal from Andromeda is the next closest large galaxy to our own may be mostly due to millisecond pulsars.
ANU Masters student Anuj Gautam led the research, which also involved scientists from The Australian Defense Force Academy, University of Canterbury, and University of Tokyo. The research was published in Nature Astronomy.