Astrophysics Colloquium: Suzanne Staggs (Princeton) FKB

11:00am to 12:00pm
Thursday March 2nd, 2017

CMB and its present  and future impacts on cosmology  

Famously, the rich angular power spectrum of the  intensity of the cosmic microwave background (CMB) reveals the state of the universe a mere 10^{13} s after the big bang.  In its fine-angular scale details, the CMB also encodes details of the CMB’s interactions with the rest of the universe in the subsequent 4^{17} s.  The CMB is slightly polarized by Thomson scattering when there is any local quadrupolar anisotropy in the distribution of the scattering electron population.  A primordial  gravitational wave (PGW) background would imprint odd-parity polarizations patterns in the CMB polarization at very large angular scales, known as B-modes.   Detection of  PGWs would have an enormous impact on our understanding of the universe in its earliest instants (as early as 10^{-32} s):  inflation, our only current explanation for the origin and statistics of structures in the universe, is accompanied by PGWs.   At small angular scales, the  CMB temperature and polarization maps provide fresh cosmological information, in part because of their sensitivity to the history of the growth rate of structures by gravitational collapse in the expanding universe.  The P5-recommended CMB S4 project aims not only to detect PGWs but also to make large deep maps of the arcminute CMB sky. The latter will permit measurements of the neutrino mass sum with two distinct methods, new sweeping constraints on the existence of light relic particles, complementary information on the nature of dark energy and on general relativity at the largest scales, and a number of other tests. I’ll review the current status of CMB data and highlight the promise of CMB S4.

SLAC, Kavli Auditorium, Building 051 *note change in location*