Computing General Relativistic effects from Newtonian N-body simulations: Frame dragging in the post-Friedmann approach

Understand

We present the first calculation of an intrinsically relativistic quantity in fully non-linear cosmolog- ical large-scale structure studies.

• Traditionally, non-linear structure formation in standard {\Lambda}CDM cosmology is studied using N-body simulations, based on Newtonian gravitational dynamics on an expanding background.
• When one derives the Newtonian regime in a way that is a consistent ap- proximation to the Einstein equations, a gravito-magnetic vector potential - giving rise to frame dragging - is present in the metric in addition to the usual Newtonian scalar potential.
• At leading order, this vector potential does not affect the matter dynamics, thus it can be computed from Newtonian N-body simulations.