BICEP/Keck Array : Probing the beginning of the Universe from the bottom of the Earth

Séminaire IPAG de Denis Barkats (CfA/ILL), jeudi 8 octobre 2020, 11h00, IPAG seminar room

The inflationary scenario generically predicts the existence of primordial gravitational waves (GW) over a wide range of amplitudes. Currently the most promising method for constraining, and potentially detecting this inflationary GW background is to search for the imprint of these tensor perturbations in the cosmic microwave background (CMB) B-mode polarization. Detecting this faint B-mode pattern requires making maps of unprecedented sensitivity, while separating the faint polarization signals intrinsic to the CMB from other signals (including polarized emission from dust and electrons in our own galaxy and patterns caused by weak gravitational lensing of large scale structure).

The BICEP/Keck (BK) series of experiments target this primordial signature by observing the polarized microwave sky at degree-scale resolution from the South Pole. Our small aperture telescopes have produced the deepest-ever maps of CMB polarization in four frequency bands thus yielding the most stringent constraints on primordial inflation to date. They are exploiting the unique polar atmosphere to push these maps to high (up to 270 GHz) and low frequencies (down to 30 GHz) to separate galactic emission from CMB signals.

I will present the current status of our instruments, results, and an overview of our next-generation “stage-3” experiment BICEP Array which has started observing at the South Pole in 2020.