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Tommaso Ghigna (Oxford U.)  “The quest for CMB B-modes and the challenge of controlling systematic effects”

December 3, 2019 @ 4:00 pm - 5:00 pm

Abstract:  
The Cosmic Microwave Background has played a central role for cosmology in the past few decades. From the very first detection of its temperature more than 50 years ago to the measurement of the temperature anisotropy, every step contributed to advancing our understanding of the fundamental laws that govern our Universe. One of the most ambitious targets of current and future experiments is the detection of the primordial polarized B-mode signal. This signal is a tracer of inflation and it is expected to be most visible at large angular scales.

I will review the current status of the search for B-modes focusing on one of the main challenges: instrumental systematic effects and strategies to keep them under control. In particular I will discuss the impact of band-pass uncertainty in the presence of Galactic foregrounds. I will describe a simulation procedure developed to study the induced bias into CMB polarization maps, and the recovered tensor-to-scalar ratio parameter. I will describe the connection between the simulation results and the instrumental parameters for a representative space mission, and define requirements to minimize the effect. Furthermore, I will introduce our current plan to develop a testbed, which we can use to address multiple systematic effects without waiting for the fully assembled instrument.

The required sensitivity for a definitive measurement of the B-mode signal is extremely challenging, and focal planes of experiments are growing in size to increase the optical throughput in order to meet the requirements. This will require extra efforts in designing, fabricating, and testing all telescope components; only through meticulous knowledge of the instrument and all its sub-systems, as well as a careful calibration, we will be able to reach this ambitious goal.

Details

Date:
December 3, 2019
Time:
4:00 pm - 5:00 pm

Venue

50A-5132 (Sessler Conference Room)
50A-5132 + Google Map