Ponente
Descripción
The epoch of reionization marks a key phase transition in the Universe’s history, typically attributed to the formation of the first stars and galaxies. However, a range of exotic early-Universe physics (decaying particles, low-temperature reheating, and axion-like fields) could introduce additional high-redshift ionization, leaving imprints on the cosmic microwave background (CMB) polarization. In this talk, I will present recent work using Gaussian process reconstruction to extract a model-independent reionization history from Planck data. This approach places robust bounds on high-redshift optical depth, and provides a powerful discriminator against nonstandard reionization scenarios. I will then apply this framework to constrain classes of axion-based models that alter the thermal and ionization history of the early Universe. These results highlight the constraining power of the CMB in testing fundamental physics beyond the standard model, without relying on detailed assumptions about astrophysical sources.
