Time：3:00pm June 9th (Thursday)

Zoom ID：878 9134 3675，password：6360

Speaker：Prof. Elisa G.M. Ferreira（IPMU, University of São Pauloo）

Title：New physics in our universe? The Hubble tension and 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. Currently, there is no consensus 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 first review the status of the Hubble tension, and some of the models that try to address it, focusnig on the EDE model and its current constraints. I will show that previous analysis suffered from statistical effects that biased their result towards 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. 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.

Bio: Elisa is an Assistant Professor at the Kavli IPMU in Japan, and at the Institute of Physics of the University of São Paulo, in Brazil. She received her PhD from McGill University. After that she was a postdoc at the Max Planck Institute for Astrophysics in Germany. Her field of research is in the interface between cosmology, astrophysics, and high energy physics. Her work focuses mostly on studying the dark sector. More specifically she is worried about dark matter, focusing on ultra-light dark matter, and the late expansion of the universe, studying the phenomenology of dark energy. Testing those models using the current observational probes and new observational windows is also part of her research.

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