Galactic dust may alter inflation’s gravitational wave signal

New Scientist : Last month’s potential discovery of gravitational waves in the cosmic background radiation may help prove the universe experienced inflation. But the polarization of the radiation that BICEP2 detected may have another cause—dust from the Milky Way. The experiment pointed away from the dustiest parts of the sky, and researchers estimated the effect of dust at less than 20% of the detected signal. However, Hao Liu of the University of Copenhagen and his colleagues say that the estimate is incorrect. They used radio telescopes to plot the distribution of Milky Way dust and found a large band that passed through the area that BICEP2 was observing. They are not sure of the exact effect the band had on the BICEP2 signal, but they are sure it is larger than the original estimate. However, the effect may not be so large as to completely overturn the original finding. In fact, the strength of the original finding was larger than predicted by theory, and a recalculation using the effect of the increased dust may bring the signal down to predicted levels.