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A paper appeared at the arXiv.org (in April or May) claimed that the writers have found the gamma rays emitted by annihilation of dark matter in a satellite galaxy of the Milky Way by examining the Fermi data. I cannot find this article anymore. (It is possible that the writers withdrew the article.) Has someone actually detected gamma rays emitted by neutralino (or any other dark matter) annihilation?

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    $\begingroup$ Perhaps arxiv.org/abs/1503.02320 ? $\endgroup$ – David H Jun 27 '15 at 21:32
  • $\begingroup$ By this question, I was hoping to get an expert opinion on the status of the DM detection even-though I accepted the given answer. What is the reason for the down vote? It would be helpful to know why one would think this is a bad question. I stayed away from groups which down vote questions with no apparent reason. I hope I do not have to stay away from this group, especially when it is in the beta mode. $\endgroup$ – Sony Jun 28 '15 at 17:09
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Is it the paper David H pointed out, by Geringer-Sameth et al. (2015)? If so, then I should point out that they're not the first. Just using Wikipedia, I came across Weniger (2012) and Albert et al. (2008).

Geringer-Sameth et al.'s abstract reads (in part)

We present a search for gamma-ray emission from the direction of the newly discovered dwarf galaxy Reticulum 2. . . . Reticulum 2 has the most significant gamma-ray signal of any known dwarf galaxy. If Reticulum 2 has a dark matter halo that is similar to those inferred for other nearby dwarfs, the signal is consistent with the s-wave relic abundance cross section for annihilation.

Albert et al. also studied a dwarf galaxy:

The nearby dwarf spheroidal galaxy Draco, with its high mass to light ratio, is one of the most auspicious targets for indirect dark matter (DM) searches. Annihilation of hypothetical DM particles can result in high-energy γ-rays, e.g., from neutralino annihilation in the supersymmetric framework. A search for a possible DM signal originating from Draco was performed with the MAGIC telescope during 2007.

The point is, this has been done before. These folks aren't the first.


Has someone actually detected gamma rays emitted by neutralino (or any other dark matter) annihilation?

More analysis is probably needed. I'll quote the paper itself:

While Ret2's X-ray signal is tantalizing, it would be premature to conclude it has a dark matter origin. Among alternative explanations, perhaps the most mundane is the possibility that an extragalactic source lies in the same direction. Searching the BZCAT [54] and CRATES [55] catalogs reveals a CRATES quasar (J033553-543026) that is 0:46 from Ret2. Further work must be done to determine whether this particular source contributes to the emission, though we note that at spectrum radio quasars rarely have a spectral index less than 2 [56]. One of the much-discussed astrophysical explanations for the apparent Galactic Center excess is millisecond pulsars [24, 26, 57{61]. In the case of Ret2, it is the high-energy behavior which disfavors a pulsar model, as millisecond pulsars exhibit an exponential cut-offat around 2.5 to 4 GeV [26, 30, 61{64]. Alternatively, high-energy cosmic ray production could potentially arise in the vicinity of young massive stars. Upcoming photo-metric and spectroscopic analysis of Ret2 will check this possibility.

Don't jump to conclusions. They didn't. It stinks, but the answer to your question is, "Nobody's sure."

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