Gamma-ray data from the Fermi Large Area Telescope reveal an unexplained, apparently diffuse signal from the Galactic bulge. Known as Galactic Centre Excess, this unexpected concentration of gamma-rays emerging from the center of our galaxy has long puzzled astronomers.
Scientists from the Australian National University (ANU) offered an alternative explanation for this strange galactic signal. They suggest that this signal might be generated by a specific type of rapidly-rotating neutron star.
Co-author of the study Associate Professor Roland Crocker said, “Our work does not throw any doubt on the existence of the signal, but offers another potential source. It is based on millisecond pulsars — neutron stars that spin quickly — around 100 times a second.”
“Scientists have previously detected gamma-ray emissions from individual millisecond pulsars in the neighborhood of the solar system, so we know these objects emit gamma-rays. Our model demonstrates that the integrated emission from a whole population of such stars, around 100,000 in number, would produce a signal entirely compatible with the Galactic Centre Excess.”
The signal was long claimed as a signature of dark matter. Hence, the discovery may mean scientists have to re-think where they look for clues about dark matter.
- Gautam, A., Crocker, R.M., Ferrario, L. et al. Millisecond pulsars from accretion-induced collapse as the origin of the Galactic Centre gamma-ray excess signal. Nat Astron (2022). DOI: 10.1038/s41550-022-01658-3