Recent observations such as H0 and cosmic birefringence challenge the Standard cosmological model of ΛCDM. We introduce the Ultralight Axion-like model of Early Dark Energy (EDE). With the potential of n=3, we work the observations of the EB mode of the cosmic microwave background (CMB) radiation and local expansion rate measurements. Our results show that the shape of the CMB EB angular power spectrum is sensitive to the background cosmological parameters. We find that the EDE model with n=3 can provide a good fit to the observed CMB EB spectra, consistent with the locally measured value of the Hubble constant. Our result is the first to show that axion-like EDE can provide a unified explanation for the observed cosmic birefringence and the Hubble tension.

Biography

Prof. Bum-Hoon Lee obtained his Ph.D. from Columbia University in 1989, and then became a professor at Hanyang University and Sogang University. From 2005 to 2014, he promoted the construction of QUeST (Center for Quantum Space Time) and served as the first director. After 2015, he served as the president of the Korean Physical Society (KPS), Asia Pacific Center for Theoretical Physics (APCTP), and Korea Council of High Energy Physics. He received many honors such as the SungBong Prize of the Korean Physical Society in 2023, Minister Citation of Contribution to Securing Research Ethics in 2022, Presidential Medal in 2022, and Minister Citation of Contribution to the Basic Research Promotion in 2012. He is also the editor of International Journal of Physics A, Modern Physics Letters A. His works have been cited more than 3000 times, with an H-index of 30. His recent research interests include gravity, cosmology, and string theory.

Inviter: Li Li