SACKLER LECTURE 2014

Speaker: John M. Kovac
 Harvard University

Dr. John M. Kovac is Associate Professor of Astronomy and Physics at Harvard University. His cosmology research focuses on observations of the cosmic microwave background (CMB) to reveal signatures of the physics that drove the birth of the universe, the evolution of its structure, and its present-day expansion. His research over the past two decades has involved the design, deployment, and operation of eight generations of CMB telescopes at the Amundsen-Scott Station at the South Pole. In 2002 his PhD work, with John Carlstrom on the DASI project, included the first detection of polarization of the CMB. He is the leader of the BICEP2 project and along with colleagues Clem Pryke,Chao-Lin Kuo, and Jamie Bock he co-leads the BICEP and Keck Array series of experiments, which presently also includes the Keck Array and BICEP3.

Title: " Measurements of B-mode Polarization: Status and Future Prospects"

Abstract
The BICEP2 experiment is a cosmic microwave background (CMB) polarimeter specifically designed to search for the signal of inflationary gravitational waves in the B-mode power spectrum. It has made maps of unprecedented sensitivity at degree angular scales over 2% of the sky, observing from the South Pole between 2010 and 2012. In March 2014 the BICEP2 team reported a high signal-to-noise detection of B-mode polarization at 150 GHz, well above the level typically predicted by galactic foreground models for that region of sky, and consistent with a large contribution from inflationary gravitational waves. The Planck satellite subsequently reported higher-frequency results in May and September indicating that foreground models most likely under-predict the levels of polarized galactic dust. While these studies reported large uncertainties on the BICEP2 field, they highlight the urgency of work to determine whether the BICEP2 B-mode signal is entirely galactic or includes a contribution from inflation. Since July, the BICEP2 and Planck collaborations have been analyzing their data together to reduce uncertainties on this key question. Meanwhile, BICEP2's successor the Keck Array has been pushing to greater sensitivity at both 150 and 95 GHz. Our team is currently deploying the BICEP3 telescope and upgrades for Keck Array, while other teams are also pushing the limits of ground-based and balloon-borne B-mode measurements with unprecedented power. I will report on the current status and prospects for this fast-moving and exciting field.