The observer-dependence of the Hubble parameter

Given the exponential growth on the upcoming supernovae data available, the possibilities of rigorously testing the cosmological principle becomes ever more real. One of the ways to do so is by measuring the multipole decomposition of the Hubble and deceleration parameters.

 

In this presentation, I will discuss the observational-theoretical approach, initially introduced by Kristian & Sachs, which allows for the interpretation of data in non-homogeneous and anisotropic universes. I will also explore the effects introduced by the relative motion between the observer and the matter frame, and show how the induced kinematic dipole can be disentangled from intrinsic anisotropies in the matter distributions. To conclude, I will show that the luminosity distance must be corrected depending on the chosen frame of the observer (z_cmb vs. z_hel).