Galactic Cosmic Ray Model Works without Physics, and That is Bad
upstart writes in with an IRC submission for SoyCow1337:
Galactic cosmic ray model works without physics, and that is bad:
Way back when the world was young and I still attended physics conferences, I got very excited by galactic cosmic rays. There seemed to be more cosmic rays than expected coming from the center of our galaxy. Those excess cosmic rays might be evidence for dark matter, which would be a big breakthrough if confirmed. Later modeling of cosmic ray sources showed that the extra cosmic rays were probably not coming from the annihilation of dark matter. But, now it seems we are back to square one, because that model may not have been accurate.
[...]Except that the fitting procedure turns out to be not so robust after all. A pair of scientists performed the fitting procedure on model data but modified the availability of the types of sources that could be fit (called templates) and played with the amount of cosmic rays from dark matter. They found that the model almost always drove the dark matter contribution to zero. The net result was that, even if up to 15 percent of the cosmic ray flux was due to dark matter, the model would still report a dark matter contribution that was near zero.
The researchers also tested the fit on real data. They took observational data and modified it by adding a dark matter contribution to it. As with the model data, they found that the fitting procedure attributed all the dark matter signal to other sources. Only if they set the dark matter contribution to around 15 percent or higher would it start showing up in the fitting results.
Although the results might be explained by a coincidence, it seems more likely that the statistical procedure is simply not good enough. The consequence is that the dark matter explanation for the cosmic ray excess is back on the table.
Revival of the Dark Matter Hypothesis for the Galactic Center Gamma-Ray Excess Rebecca K. Leane, Tracy R. Slatyer.Phys. Rev. Lett. 123, 241101 - Published 11 December 2019.
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