Tuesday, May 15, 2012

Links for the week - dark matter special

A longer blog posting should ready by the weekend, but is proving a little harder to write than I had hoped. In the meantime, here is a collection of interesting things to read elsewhere. I will make this sort of a roundup of worthwhile links a weekly feature on this blog, though it will make more sense to put it out at the weekend next time. Anyway, here you go:

Physics links:
  • Dark matter detection experiments have been in the news a lot recently. A couple of pre-prints have claimed to have seen some tentative evidence for a dark matter annihilation signal in gamma-ray data from the Large Area Telescope on the Fermi satellite, that somehow wasn't seen by the Fermi guys themselves. Matt Strassler discusses the first of these papers here. Rhys provides a nice short summary of both; you may also want to read a more bombastic discussion on Lubos Motl's blog.
  • The Cryogenic Dark Matter Search (CDMS) detection experiment earlier this year found no evidence for an annual modulation of dark matter interaction events in its detector, apparently contradicting earlier experiments DAMA and COGENT. A new pre-print from two members of COGENT claims CDMS mis-analysed their own data and there isn't a contradiction. (I'm not sure what to make of this: the argument seems pretty straightforward but I'm no expert so I might be missing some elementary things. Comments welcome!)
  • To make the story murkier still, this paper accepted by the Astrophysical Journal claims to find no evidence for dark matter in the solar neighbourhood based on the dynamics of stars in our galaxy, which would presumably rule out the possibility of direct detection. There are a number of caveats, so caution is advised: see here and Matt Strassler's post above. But then this paper, accompanied by this press release, makes an even more inflammatory claim about the non-existence of dark matter. Peter Coles provides a sceptical review (and entertaining arguments in the comments section!).
  • In case you are now thoroughly confused by the status of evidence for dark matter, Sean Carroll at Cosmic Variance gives us the transcript of a debate that sums up the main cosmological issues.
Phew, what a lot of dark matter. I realise some of the links above are not very recent — this blog is new and has some catching up to do! Now for other stuff.

Other links:
    • In the Guardian, Barney Ronay has a brilliant piece recalling an inspiring Olympic moment: Michael Johnson breaking the 200 m world record at Atlanta '96. If, like me, you watched the race at the time, you will have it forever seared in your memory. If not, here's a video:

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