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In this talk, I will summarize growing observational evidence from JWST that suggests accelerated structure formation in the early universe. Some are challenging canonical galaxy formation models in the standard LambdaCDM cosmology. I will begin by briefly reviewing potential resolutions to these tensions within the standard cosmological framework. Then I will focus on two extensions beyond the standard model that offer promising explanations for the anomalies. The first is early dark energy (EDE), a phenomenological model that introduces an additional energy component active prior to recombination. EDE not only provides a compelling solution to the Hubble tension but also naturally promotes early structure formation, offering a unified explanation for multiple cosmological tensions. The second is self-interacting dark matter, which can induce gravothermal collapse in massive halos in the early universe, potentially seeding supermassive black holes (SMBHs). This mechanism may account for some of the peculiar faint obscured SMBHs (the so-called "Little Red Dots") discovered by JWST.

BIO

Xuejian (Jacob) is a postdoctoral researcher at the Kavli Institute for Astrophysics and Space Research at Massachusetts Institute of Technology. Xuejian received a Bachelor’s degree from Peking University and a Ph.D. degree in Physics at the California Institute of Technology supervised by Prof. Philip Hopkins. His research interests are the formation and evolution of high-redshift galaxies and supermassive black holes in light of JWST observations, and the potential of using high-redshift observables contraining fundamental physics. He is also part of the FIRE and THESAN collaboration in developing new cosmological radiation-hydrodynamic simulations of high-redshift galaxies.

Host: Hui Li