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Scaling Transformations and Constraints on Light Relics from CMB Observations

November 17, 2022
4:35 PM - 5:05 PM
Pupin 1402

Seminar by Lloyd Knox, UC Davis

Early universe scenarios that lead to the production of additional light relics, beyond the photons and neutrinos expected in the standard cosmological model, can be constrained due to their influence on cosmological observables. In this talk we ask what makes these constraints possible. We introduce a scaling transformation that uniformly scales up all the dimensionful quantities in the Einstein-Boltzmann evolution equations, while leaving all dimensionless observables (such as CMB power spectra) exactly invariant. We then show the impact on observables of various departures from this uniform scaling, to gain insight into the origin of constraints on light relics in cosmological models of varying complexity.

Host: Zoltan Haiman