Dark matter is highly sought-after but like the unicorn, it is an elusive match for its hunters.
Physics bods have been a-huntin’ for dark matter here on Earth for some time now. They’ve set an impressive number of traps all over the planet and and found zilch.
So they’ve asked the astrobods to help out by looking for indirect evidence. If dark matter particles ever bang into each other, they might annihilate leaving a signature that we can see (or so the thinking goes).
Today, Dan “Super” Hooper from the Fermi National Accelerator in Illinois gives us the low down on the various candidates that the eggheads are looking at.
They’ve looked at the unexplained excess of positrons in cosmic rays, at the unexplained excess of 511KeV photons coming out of the galactic bulge, at the unexplained excess of gamma rays at energies above 1GeV coming from within our galaxy and from outside it and the unexplained excess of microwave emissions from the centre of the Milky Way as measured by the WMAP spacecraft.
None of these signals is particularly strong but that don’t bother dark matter theorists: if it don’t have a current explanation, it’s gotta be dark matter, right?
Whatever happened to that old fashioned notion of hypothesis testing.
I know what ya’ll thinkin and I’ll wager it includes the words “clutching” and “straws”. Myself? I’m rootin’ for the unicorn.
Ref: arxiv.org/abs/0710.2062: Indirect Searches For Dark Matter