Isolating relativistic effects in large-scale structure

Understand

We present a fully relativistic calculation of the observed galaxy number counts in the linear regime.

• We show that besides the density fluctuations and redshift-space distortions, various relativistic effects contribute to observations at large scales.
• These effects all have the same physical origin: they result from the fact that our coordinate system, namely the galaxy redshift and the incoming photons' direction, is distorted by inhomogeneities in our universe.
• We then discuss the impact of the relativistic effects on the angular power spectrum and on the two-point correlation function in configuration space.