The results do not touch on the most controversial claim in cosmology in decades. In March, researchers working with BICEP2, a specialized telescope at the South Pole, reported that they had detected faint, pinwheel-like swirls in the polarization of the CMB when mapped across a small patch of sky. Such swirls, or B modes, could be a sign of gravitational waves rippling through the universe a split second after the big bang and proof that it underwent a bizarre exponential growth spurt known as inflation. However, in September Planck researchers released a sky map that showed that much of the BICEP signal likely comes from dust within our galaxy. Many people are eager to know whether the BICEP teams claim of spotting B modes will survive the joint analysis with the Planck team. Weve advanced a lot with the work, and were writing up the paper, says Jan Tauber, a Planck project scientist with the European Space Agency in Noordwijk, the Netherlands. Tauber declined to say when the results of that analysis would be announced publicly. What you can say with certainty is that [the strength] of their measurement is going to go down, he says. To determine how much of the BICEP signal is due to dust, researchers have to compare or cross-correlate BICEPs map of the patch of the sky with Plancks map of the polarized emissions from dust. Some researchers outside the two teams have already tried to do that and have shown that the two maps are largely the same, says Uroš Seljak, a cosmologist at the University of California, Berkeley. That suggests the purported signal is mostly from dust. Planck by itself likely does not have the sensitivity to detect gravitational waves, Seljak says. Some cosmologists suspect that the BICEP signal will disappear altogether and that the joint Planck-BICEP analysis will set only an upper limit on the strength of the B-mode signal. Such a limit could rule out certain simple theoretical models of what drove inflation, Spergel says: Thats not as much fun as discovering gravitational waves, but its progress.
Posted on: Wed, 03 Dec 2014 15:43:55 +0000
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