Seminari Generali

BICEP2 gravitational wave result bites the dust. New Planck data reveal possible contamination.

by Francesco Piacentini (Dipartimento di Fisica, La Sapienza)

Europe/Rome
Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

Aula Conversi

Dip. di Fisica - Edificio G. Marconi

Description
In March 2014 the BICEP2 team sensationally claimed the first detection of primordial gravitational waves imprinted in the polarization of the Cosmic Microwave Background. It has soon been noted how that result lacked in control of possible contamination from inter-stellar dust in our Galaxy, due to absence of data. The Planck space telescope is now presenting the missing data: a map of the polarization generated by galactic dust, obtained by its unique 353 GHz polarization sensitive channel. This map is used to calculate the dust polarization angular power spectra. We show that even in the faintest dust-emitting regions there are no “clean” windows in the sky where primordial CMB B-mode polarization measurements could be made without subtraction of foreground emission. In particular, Planck team is measuring a possible contamination of the BICEP2 result as large as their detection. In this seminar, I present the last Planck result, and the status of this rapidly evolving research activity.