Friday, November 25, 2022 at 4 pm in-person and by videoconference

For our next journal club we'll have a special seminar from Prof. Elisa Ferreira (Kavli IPMU & IFUSP):

• Title: Resolving the Hubble tension with Early Dark Energy

• Abstract: One of the key topics in cosmology nowadays is the Hubble tension, a discrepancy in the present value of the expansion of our universe (H0) coming from direct (local), and indirect measurements of H0. The most significant tension is between the inferred H0 from the cosmic microwave background (CMB) by Planck, for the ΛCDM model, and the local one from SHOES, reaching a 5σ discrepancy. This tension could hint at new physics beyond the standard ΛCDM model. A dark energy-like component in the early universe, known as early dark energy (EDE), is a proposed solution to the Hubble tension. There was a lot of discussion in the literature as to whether EDE can simultaneously solve the Hubble tension and provide an adequate fit to the data from the CMB and large-scale structure of the universe. In this talk, I will show that previous analyses suffered from statistical effects that biased their result toward the conclusion that only a small fraction of EDE was allowed by data. We proposed a frequentists analysis that provides a powerful tool to understand whether EDE is a possible solution to the Hubble tension and show that indeed the EDE model can restore cosmic concordance and resolve the Hubble tension. I will discuss the role of complementary statistical methods to analyze cosmological models. If time permits, I will also talk about the role of the massive neutrinos in these scenarios and if neutrinos can make EDE a more viable model for our universe.