Another blow for the dark matter interpretation of the galactic centre excess

August 6, 2018, Delta Institute for Theoretical Physics
Figure 1: 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: Christoph Weniger, University of Amsterdam/FermiLAT

For almost 10 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 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 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 signal from the self-annihilation of dark matter particles in the inner galaxy. Finding such a signal would confirm that dark matter, which has 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, a recent study shows 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 observation at other frequencies up to now.

Where there are stars, there is radiation

"Understanding in detail the morphology [the location and shape] and spectrum [the combined frequencies] of the excess emission is of vital importance for discriminating between the dark matter and astrophysical interpretations of the galactic centre excess radiation," says Christoph Weniger, one of the researchers that conducted the study. A new study by researchers at the University of Amsterdam and the Laboratoire d"Annecy-le-Vieux de Physique Théorique, a research unit of the French Centre National de la Recherche Scientifique, found strong evidence that the emission actually seems to come from regions where there is also a large amount of stellar mass in the galactic bulge (the 'boxy bulge') and centre (the 'nuclear bulge'). Furthermore, the researchers found that the light-to-mass ratio in the galactic bulge and centre are mutually consistent, so that the gamma ray GeV emission is a surprisingly accurate tracer of stellar mass in the inner galaxy (figure 2). This study was based on a new analysis tool, Sky Factorization with Adaptive Constrained Templates (SkyFACT), developed by the researchers themselves, which combines physical modeling with image analysis.

Figure 2: Comparison of the stellar mass (horizontal axis) and gamma-ray luminosity (vertical axis) for the "boxy bulge” (in blue) and for the “nuclear bulge” (in green). The prediction for a population of millisecond pulsars in the Galactic disk (in red) and the bulge of the nearby Andromeda galaxy (M31, in pink) are also shown. Stellar mass and luminosity are proportional to each other in the inner Galaxy (dashed line), which shows that the mysterious excess radiation very likely has a stellar origin and is not coming from dark matter. Credit: Christoph Weniger, University of Amsterdam

The findings support the millisecond pulsar interpretation of the excess emission, since neither a dark matter signal nor other astrophysical interpretations are expected to show such a correlation. "The results will help guide upcoming radio searches for this hidden population of millisecond pulsars in the galactic bulge with MeerKAT and the future Square Kilometre Array," said Francesca Calore, another of the paper's authors. "This makes these upcoming searches even more promising."

Explore further: New study suggests galactic bulge emissions not due to dark matter

More information: R. Bartels, E. Storm, C. Weniger and F. Calore, The Fermi-LAT GeV excess traces stellar mass in the Galactic bulge, Nature Astronomy 2018. DOI: doi.org/10.1038/s41550-018-0531-z
Preprint: arxiv.org/abs/1711.04778

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fthompson495
1.4 / 5 (9) Aug 06, 2018
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

'The Milky Way's dark matter halo appears to be lopsided'
http://arxiv.org/abs/0903.3802

"the dark matter halo of the Milky Way is dominantly lopsided in nature."

The Milky Way's halo is lopsided due to the ordinary matter in the Milky Way moving through and displacing the supersolid dark matter, analogous to a submarine moving through and displacing the water.
Pearlman_CTA
3.7 / 5 (3) Aug 06, 2018
Nice work/research
Another feather in the cap for SPIRAL cosmological redshift hypothesis and model, that would predict the CR but not the missing dark matter and energy.
Surveillance_Egg_Unit
3.4 / 5 (5) Aug 06, 2018
@fthompson
I have to give you a one rating for continuing ignorance and for gross negligence of the Truth. Dark Matter theory is false and is perpetrated on the unwary for lack of a better explanation.
joel in oakland
3 / 5 (2) Aug 07, 2018
@SEU
Not sure what you mean. There isn't any DM theory with any evidence - that's the problem, isn't it? There's MOND, but it only holds for some regions where the DM phenomenon/a are detected. And it has no explanation as to why gravity would change from inverse square to linear. Maybe you would elaborate further? Thanks

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