Science from the large scale cosmic microwave background polarization structure

ongoing

Observational cosmology is moving towards its next major milestone: high-precision measurements of the cosmic microwave background polarization with the goal of detecting and characterizing the primordial B-modes. These polarization patterns would provide a unique picture of the early Universe, shedding the light on the conditions at that time, be it cosmic inflation, gauge fields, or more exotic possibilities. In a regime of energy where standard models are expected to break, such observations could revolutionize our current picture of cosmology and high energy physics. Characterizing such signal requires (1) reaching extremely low instrumental sensitivity levels and (2) controlling instrumental and astrophysical systematic effects with unprecedented fidelity. While (1) is about to be reached with the planned deployment of funded, cutting-edge observatories such as the Simons Array/Observatory, CMB-S4 and LiteBIRD, (2) is already limiting the current constraints and will be studied and uniquely mitigated by SciPol. My project is an opportunity to claim a leadership role for Europe in one of the most active and impactful research areas in physics, complementing the hardware efforts led by the US and Japan. I will: - construct accurate, open-source and versatile models for the instrumental, astrophysical signals and noise properties; - develop and exploit new, general algorithms adjusting previous models from observations, and producing a unique set of instrument- and foreground-corrected maps; - make a statistically robust cosmological inference of these, especially on the large scale, implementing a gravitational lensing correction. I have been at the forefront of this research for the last 10 years, made key contributions to the analysis and scientific exploitation of the POLARBEAR data sets, and to preparations and scientific optimization of the forthcoming efforts. I am consequently uniquely positioned to deliver the objectives of the proposed work.