Gamma-ray glows and DM

For some time, it has been suggested that a possible source of astrophysical gamma-rays is the annihilation of dark matter particles. When two DM particles meet, it is hypothesised that they can annihilate each other, with the energy of this process producing very-high-energy photons known as gamma-rays.

One suggested outcome of this is that a peak in the observed number of gamma-ray photons may be observed at a specific energy (or frequency or wavelength)- that is, an emission line in a gamma-ray spectrum.

However, although this has yet to be demonstrated conclusively, its investigation does remain a goal of gamma-ray astronomers.

Another way of approaching the issue is to map the distribution of gamma-ray emission across the sky (in particular, the diffuse gamma-ray emission- an all-pervading, sky-covering glow that is seen once all known foreground sources have been removed) and to see how, or indeed if, it correlates with the distribution of ordinary matter.

Recent work comparing gamma-ray observations from the Fermi satellite with optical data from the Dark Energy Survey, suggest that there is indeed a correlation between the diffuse gamma-ray glow and the distribution of matter throughout the universe- a not-unexpected result, but this work shows the first conclusive evidence of the connection.

Now, this is not proof that the diffuse gamma-rays come from DM annihilation; but the result is not inconsistent with perhaps some of that glow coming from this process. Further work is required, both from an extension of the current project and through future observations from planned ground- and space-based instruments.

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