Speaker
Description
Recent tensions in cosmological data strongly suggest that the standard $\Lambda$CDM picture may be incomplete. Many attempts have been made to alleviate the famous Hubble tension, out of which Early Dark Energy models offered one of the best theoretical frameworks so far that can possibly close the gap between early and late-time observations by dynamically modifying the spacetime background prior to recombination. However, the introduction of an additional accelerating component in the early Universe changes the Hubble expansion rate during the radiation-dominated epoch. This kinematic deviation from standard General Relativistic dynamics shifts the thermodynamics of the weak freeze-out, modifying the predictions of Big Bang Nucleosynthesis. To determine the viability of these modified expansion histories, we investigate the impact of four early dark energy formulations on the primordial element abundances: a baseline cosmological constant, alongside linear, polytropic, and temperature-dependent equations of state. We test these models against observational bounds to map the allowable parameter space, and we discuss which dynamical modifications are ruled out by nucleosynthesis constraints.
| Topic | Early Universe Thermodynamics |
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