Joan van der Waals Colloquium

Location: De Sitterzaal, Oort Building

Time: 16.00 - 17.00hours (drinks afterwards)

abstract
Dorothea Samtleben
(NIKHEF)
“News from the oldest light”

Since its discovery more than four decades ago the Cosmic Microwave Background Radiation (CMBR) has served as a rich source of information on the early Universe. Measurements of its temperature anisotropies were instrumental in establishing our current cosmological model. The focus of experiments lies now in precise measurements of the tiny polarization anisotropies. The CMBR polarization pattern is commonly divided
into E-modes which derive like the temperature anisotropies from density fluctuations in the early Universe and B-modes which are due to lensing by the mass in the line of sight but are also expected as signature of primordial gravity waves and with that provide unique access to the inflationary era in the very first moments of the Universe. While Emodes have already been detected it is only now that the sensitivity of upcoming experiments approaches the level where B-modes are expected. I will introduce the status of current measurements and illustrate the challenges and
potential of future measurements by focussing on the Q/U Imaging ExperimenT (QUIET), a ground-based experiment in the Atacama desert in Chile. We collected data from 2008 to 2010 with two coherent radiometer arrays of 19 (90) elements at 40 (90) GHz and first results from the 40 GHz array will be presented.