Measuring anisotropic stress with relativistic effects

Understand

One of the main goal of large-scale structure surveys is to test the consistency of General Relativity at cosmological scales.

• In the $\Lambda$CDM model of cosmology, the relations between the fields describing the geometry and the content of our Universe are uniquely determined.
• In particular, the two gravitational potentials -- that describe the spatial and temporal fluctuations in the geometry -- are equal.
• Whereas large classes of dark energy models preserve this equality, theories of modified gravity generally create a difference between the potentials, known as anisotropic stress.