Speaker
Description
We present a fully relativistic treatment of cosmological peculiar velocities within General Relativity, moving beyond the standard Newtonian approximation commonly employed in large-scale structure studies. Peculiar velocity fields are derived from analytic solutions of Einstein’s equations sourced by non-perfect fluids and interpreted through frame transformations with respect to a cosmological background identified with the CMB rest frame. In this framework, non-trivial velocity fields arise naturally from relativistic effects.
As a toy model, we further analyze localized inhomogeneous regions embedded in a ΛCDM background, providing a self-consistent relativistic description of cold dark matter flows in cosmic structures. This approach enables a direct connection between relativistic inhomogeneities, CMB-frame velocities, and local expansion rates. Our results show qualitative agreement with observed peculiar velocity magnitudes and indicate that relativistic modeling of inhomogeneous structures may have non-negligible implications for large-scale bulk flows and inferred values of the Hubble expansion, offering a new perspective on current observational tensions.