Okay, folks, check this one out:

Milky Way Gamma Ray Distribution

Relevant quote:

A team of astrophysicists has solved the mystery of the distribution of gamma rays in our Milky Way galaxy.  While some researchers thought the distribution suggested a form of undetectable “dark matter”, the team from the University of California, San Diego, proposed an explanation based on standard physical models of the galaxy.

Comments?

Regards,
Mike Petersen

That's pretty interesting on the topic of dark matter. I know one thing dark matter proponents have been looking for is the possibility that even though their putative dark matter may not interact in any way other than gravitationally, that some dark matter particles might be able to self-annihilate.

Covering off gamma rays with plain old positrons¹ darkens that hope. Truth be told, self-annihilation isn't a given in dark matter hypotheses... but I am sure they were hoping anyhow :)

¹ Funny to have them be labeled as "antimatter positrons", as though they could be anything else, but I guess they are not necessarily known as antimatter to a public used to Data's positronic brain without the realization that his brain could explode or at least inundate his compatriots with gamma rays :)