B-mode Detection with an Extended Planck Mission

The Planck satellite has a nominal mission lifetime of 14 months allowing two complete surveys of the sky. Here we investigate the potential of an extended Planck mission of four sky surveys to constrain primordial B-mode anisotropies in the presence of dominant Galactic polarized foreground emission. An extendedPlanck mission is capable of powerful constraints on primordialB-modes at low multipoles, which cannot be probed by ground based or sub-orbital experiments. A tensor-scalar ratio of r = 0.05 can be detected at a high significance level by an extended Planckmission and it should be possible to set a 95% upper limit of r ≲ 0.03 if the tensor-scalar ratio is vanishingly small. Furthermore, extending the Planck mission to four sky surveys offers better control of polarized Galactic dust emission, since the 217 GHz frequency band can be used as an effective dust template in addition to the 353 GHz channel.