A general relativistic signature in the galaxy bispectrum: the local effects of observing on the lightcone

Understand

Next-generation galaxy surveys will increasingly rely on the galaxy bispectrum to improve cosmological constraints, especially on primordial non-Gaussianity.

• A key theoretical requirement that remains to be developed is the analysis of general relativistic effects on the bispectrum, which arise from observing galaxies on the past lightcone, {as well as from relativistic corrections to the dynamics}.
• {As an initial step towards a fully relativistic analysis of the galaxy bispectrum, we compute for the first time the local relativistic lightcone effects on the bispectrum,} which come from Doppler and gravitational potential contributions.
• For the galaxy bispectrum, the problem is much more complex than for the power spectrum, since we need the lightcone corrections at second order.