报告问题 (Title)：Probing the dynamics of dark energy from latest cosmological observations（从目今宇宙学视察探讨动力学暗能量）

报告人 (Speaker)： 蔡一夫 教授（中国科学手艺大学）

报告时间 (Time)：2025年2月21日(周五) 10:00-11:30

报告所在 (Place)：校本部 D117

约请人 (Inviter)：葛先辉

主理部分：理学院物理系

摘要 (Abstract)：

Astonishingly, human beings discovered that distant Type Ia supernovae (SN Ia) were accelerating away at an increasing pace. This led to the great discovery of late-time cosmic acceleration and brought us the concept of dark energy, responsible for such a phenomenon, but the underlying nature remains mysterious. Theoretically, modified gravity can be a framework to provide an alternative explanation for the the existence of dark energy. In this talk, we will go further into the effective field theory of f(T) gravity and beyond. Then using the latest Dark Energy Spectroscopic Instrument (DESI) data combined with other observations, we reconstructed the cosmological background evolution and find that the reconstructed dark-energy equation-of-state (EoS) parameter w(z) exhibits the so-called quintom-B behavior, crossing ?1 from phantom to quintessence regime as the universe expands. In particular, we reconstruct the corresponding actions for f(R), f(T), and f(Q) gravity, respectively. We conclude that, certain modified gravity such as metric-affine gravity can exhibit the quintom dynamics and fit the recent DESI data efficiently, and for all cases the quadratic deviation from the ΛCDM scenario is mildly favored.