Speaker
Description
Many of the predictions of theoretical cosmology are generated by perturbing around a background FLRW space-time. This procedure is problematic, because the dependence of observables on the perturbations of the metric tensor varies with the choice of coordinates (or gauge) in the perturbed space-time. Moreover, the gauge choice is rarely uniform, as for example luminosity distances and peculiar velocities are usually calculated in the Newtonian gauge, whereas matter densities and fluctuations in the CMB temperature are conventionally calculated in the synchronous gauge.
In this talk, I will explain how the correct gauge-invariant formulas for a number of important observables can be derived, and use them to revise the two-point correlation functions for the local density and peculiar velocity fields, as well as the spectrum of anisotropies induced in the CMB by perturbations in the gravitational potential on the surface of last scattering (i.e. the Sachs-Wolfe effect).
| Research Area | Cosmology: late universe |
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