Starship Asterisk*

Observed gamma ray emission from the Galactic disk, with the bulge region indicated. The insets show the expected profiles of excess radiation coming from dark matter and stars respectively. The researchers were able to show that the stars profile matches the measurements much better than the dark matter profile. (Credit: Fermi-LAT/Bartels et al)

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For almost ten years, astronomers have been studying a mysterious diffuse radiation coming from the centre of our Galaxy. Originally, it was thought that this radiation could originate from the elusive dark matter particles that many researchers are hoping to find. However, physicists from the University of Amsterdam/GRAPPA and the Laboratoire d’Annecy-le-Vieux de Physique Théorique have now found further evidence that rapidly spinning neutron stars are a much more likely source for this radiation. Their findings are published today in Nature Astronomy.

Observations of the gamma-ray radiation from the Galactic centre region with the Fermi Large Area Telescope have revealed a mysterious diffuse and extended emission. Discovered almost 10 years ago, this emission generated a lot of excitement in the particle physics community, since it had all the characteristics of a long-sought-after signal from the self-annihilation of dark matter particles in the inner Galaxy.

Finding such a signal would confirm that dark matter, a substance that so far has only been observed through its gravitational effects on other objects, is made out of new fundamental particles. Moreover, it would help to determine the mass and other properties of these elusive dark matter particles. However, recent studies show that arguably the best astrophysical interpretation of the excess emission is a new population in the Galactic bulge of thousands of rapidly spinning neutron stars called millisecond pulsars, which have escaped observations at other frequencies up to now. ...

• Nature Astronomy (online 06 Aug 2018) DOI: 10.1038/s41550-018-0531-z
  arXiv.org > astro-ph > arXiv:1711.04778 > 13 Nov 2017