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The uncertainty of science: A Japanese astronomer, Tomonori Totani, yesterday published a paper claiming he had detected gamma ray radiation surrounding the center of the Milky Way that matches perfectly the predicted location of the galaxy’s dark matter halo, thus being the first direct detection of dark matter.

The graphic to the right shows that high energy gamma ray halo, as measured by the Fermi Gamma-ray Space Telescope. From the press release:

Using the latest data from the Fermi Gamma-ray Space Telescope, Professor Tomonori Totani from the Department of Astronomy at the University of Tokyo believes he has finally detected the specific gamma rays predicted by the annihilation of theoretical dark matter particles. … “We detected gamma rays with a photon energy of 20 gigaelectronvolts (or 20 billion electronvolts, an extremely large amount of energy) extending in a halolike structure toward the center of the Milky Way galaxy. The gamma-ray emission component closely matches the shape expected from the dark matter halo,” said Totani.

The observed energy spectrum, or range of gamma-ray emission intensities, matches the emission predicted from the annihilation of hypothetical WIMPs, with a mass approximately 500 times that of a proton. The frequency of WIMP annihilation estimated from the measured gamma-ray intensity also falls within the range of theoretical predictions.

Totani says this gamma radiation is not easily explained by other phenomenon, which is why he assigns it to dark matter. Other scientists are not so sure:

David Kaplan, a professor in the department of physics and astronomy at Johns Hopkins University, said it’s difficult to trace emissions back to dark matter particles with any certainty because too much is still unknown about gamma rays. “We don’t even know all the things that can produce gamma rays in the universe,” Kaplan said, adding that these high-energy emissions could also be produced by fast-spinning neutron stars or black holes that gobble up regular matter and spit out violent jets of material.

As such, even when unusual gamma-ray emissions are detected, it’s often hard to draw meaningful conclusions, according to Eric Charles, a staff scientist at Stanford University’s SLAC National Accelerator Laboratory. “There’s a lot of details we don’t understand,” he said, “and seeing a lot of gamma rays from a large part of the sky associated with the galaxy — it’s just really hard to interpret what’s going on there.” [emphasis mine]

In other words, this claim is hardly proven, and in fact should not at this point be taken very seriously. Totani has detected emissions that need explaining, but to immediately attach the gamma radiation to dark matter is risky.