I thought it was about time I gave another update on currently the most important story in astrophysics – the BICEP2 team’s possible detection of B-mode polarisation in the cosmic microwave background. I have previously blogged about this story, for example here, here and here. But, just to quickly recap, in March the BICEP2 team announced that they had detected the B-mode polarisation in the cosmic microwave background (CMB), and argued that it was evidence of gravitational waves and cosmological inflation in the very early Universe.
Since then, controversy has been the order of the day as other astrophysicists and cosmologists have argued that the BICEP2 detection was not due to the CMB at all, but rather to emission from dust in our own Milky Way galaxy. BICEP2 on their own do not have sufficient data to rule out this possibility, something they concede in their published paper. However, it would seem that the European satellite Planck do, as it has not only observed the whole sky (including the part of the sky observed by BICEP2), but has done so at five different frequencies, compared to BICEP2’s single frequency measurement.
In the last few days, it has been announced that the BICEP2 team will formally collaborate and share data with the Planck team, which I think is good news in sorting out the controversy over the BICEP2 detection sooner rather than later.
Although the Planck measurements of the polarisation of dust in our Milky Way will presumably become public at some point (as is normal with publicly funded science projects), this would not be for many more months. By formally collaborating with Planck, the BICEP2 team will get not only earlier access to the Planck data, but just as importantly will get the experts in the Planck collaboration working with them to properly interpret the Planck measurements. It is hoped by all in the astrophysics and cosmology communities that this collaboration between BICEP2 and Planck will lead to the issue of the origin of the detected B-mode polarisation being sorted out in a timely fashion, possibly even by the end of this year.
We shall have to wait and see!