Nonlinear structure formation in Nonlocal Gravity

Understand

We study the nonlinear growth of structure in nonlocal gravity models with the aid of N-body simulation and the spherical collapse and halo models.

• We focus on a model in which the inverse-squared of the d'Alembertian operator acts on the Ricci scalar in the action.
• For fixed cosmological parameters, this model differs from $\Lambda{\rm CDM}$ by having a lower late-time expansion rate and an enhanced and time-dependent gravitational strength ($\sim 6\%$ larger today).
• Compared to $\Lambda{\rm CDM}$ today, in the nonlocal model, massive haloes are slightly more abundant (by $\sim 10\%$ at $M \sim 10^{14} M_{\odot}/h$) and concentrated ($\approx 8\%$ enhancement over a range of mass scales), but their linear bias remains almost unchanged.