Hunting down horizon-scale effects with multi-wavelength surveys

Understand

Next-generation cosmological surveys will probe ever larger volumes of the Universe, including the largest scales, near and beyond the horizon.

• On these scales, the galaxy power spectrum carries signatures of local primordial non-Gaussianity (PNG) and horizon-scale general relativistic (GR) effects.
• However, cosmic variance limits the detection of horizon-scale effects.
• Combining different surveys via the multi-tracer method allows us to reduce the effect down cosmic variance.