【9.8; Seminar】2025年粒子天体物理全国重点实验室系列学术报告 #24：Exploring the Universe through the Cosmic Microwave Background: New Frontiers with POLOCALC.

时间/Time: 9月8日周一上午10:00/Monday, September 8, 10:00 a.m.

地点/Location: 多学科楼122会议室/Meeting Room 122, Multidisciplinary building

报告人/Speaker: Prof. Federico Nati

题目/Title: Exploring the Universe through the Cosmic Microwave Background: New Frontiers with POLOCALC.

主持人/Host:李雅琼/ Dr. LI Yaqiong

摘要/Abstract:

I will present a broad overview of the cosmic microwave background (CMB) observations, one of the most powerful tools in modern cosmology, providing unique insights into the physics of the early universe, the nature of dark matter and dark energy, and the physics of inflation. In this talk I will focus on ground-based experiments designed to measure CMB temperature and polarization anisotropies with unprecedented sensitivity.

A central requirement for achieving the scientific objectives of these experiments is precise calibration of the polarization angle, without which fundamental signals such as primordial B-modes or Cosmic Birefringence could remain undetected. I will introduce POLOCALC, an ERC Advanced Grant project that develops a novel, experimental approach to calibration, using air-borne polarized microwave sources. This technique enables a direct calibration of the absolute polarization angle at the 0.01° level.

The talk will therefore cover both the broad cosmological motivations and the technical innovations that are driving the next generation of CMB experiments, highlighting the path towards probing fundamental physics with ever greater accuracy.

个人简介/Biography:

Federico Nati is Professor of Experimental Cosmology at the Dept. of Physics of the Uni. of Milano-Bicocca, Italy. His research focuses on the Cosmic Microwave Background (CMB). He has extensive experience with balloon-borne telescopes, such as BLAST, and ground-based experiments, including the Atacama Cosmology Telescope (ACT) and the Simons Observatory. He is Principal Investigator of POLOCALC, an ERC Advanced Grant dedicated to developing novel air-borne calibrators for high-accuracy CMB polarimetry.