The Canadian Galactic Emission Mapper (CGEM) - An 8-10 GHz Polarization Survey to Aid in the Search for Primordial Gravitational Waves

Inflation is theorized to be a period in the very early universe in which the universe expanded by a factor of at least e 60 .If inflation took place, the gravitational waves produced during this period could have left an imprint in the earliest light we have of the universe: the Cosmic Microwave Background (CMB).Specifically, in the form of a parity-odd pattern in the polarization field, called a B-mode, uniquely sourced by primordial gravitational waves.Several efforts have been made for the past thirty years to find this signal, which would provide 'smoking gun' evidence for inflation.Among the several challenges in the search for B-modes, the presence of foregrounds between us and the CMB is one of the most difficult to overcome.The synchrotron radiation from our galaxy dominates the faint polarized emission from the CMB in its observing frequency, 100 GHz.The Canadian Galactic Emission Mapper (CGEM) is a 4 metres on-axis radiotelescope located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada.It is currently mapping the Northern sky in polarization with 0.5 degree angular resolution in a frequency range (8-10 GHz) where the galactic synchrotron emission is 10 3 times brighter than if it was observed near the CMB frequency range.CGEM will obtain high signal-to-noise Stokes Q and U maps of Galactic synchrotron and spinning dust emission.These maps will be subsequently used by B-modes search experiments to improve their foregrounds models.In this talk, I will present an overview of the CGEM experiment and its science goals.I will describe how we have designed this telescope with the goal of maximizing polarization purity, its receiver and its scan strategy.I will also outline future plans for the experiment, which we have been deploying since December 2024.