The speaker will discuss recent and ongoing work focused on attempts to restore concordance amongst cosmological data sets, motivated by discrepancies between some measurements of the cosmic expansion rate (H_0) and the matter clustering amplitude (S_8). Particular attention will be paid to scenarios invoking new physics in the high-redshift universe, including models featuring interactions between the dark matter and an Early Dark Energy(EDE) scalar field, as well as decaying particle scenarios that could lead to non-trivial evolution of the radiation density. The speaker will discuss constraints on these models derived using Cosmic Microwave Background(CMB) measurements from the Planck satellite and the Atacama Cosmology Telescope(ACT), amongst other data sets. He will also present new constraints on canonical axion-like EDE models derived from the Lyman-alpha forest, which pose a major challenge for this scenario to resolve the Hubble tension. Finally, he will conclude with a look ahead to the unprecedented constraining power of upcoming CMB analyses with ACT Data Release 6.
頻道：Zoom ID:421-480-1692 ← cosmology
講者：J. Colin Hill (Columbia University & Flatiron Insitute)
“Copernicus Webinar and Colloquium Series”: To promote scientific discussions during this pandemic, they are organizing an online seminar series, i.e. Copernicus Webinar Series, seeking the most outstanding speakers to introduce innovative ideas and important progress in the field of gravity and cosmology. This series is named after the famous Polish Astronomer, Nicolaus Copernicus, whose discovery eventually marked the dawn of modern science.