The splashback radius in symmetron gravity

Understand

The splashback radius $r_\mathrm{sp}$ has been identified in cosmological $N$-body simulations as an important scale associated with gravitational collapse and the phase-space distribution of recently accreted material.

• We employ a semi-analytical approach to study the spherical collapse of dark matter haloes in symmetron gravity and provide insights into how the phenomenology of splashback is affected.
• The symmetron is a scalar-tensor theory of gravity which exhibits a screening mechanism whereby higher-density regions are screened from the effects of a fifth force.
• In this model, we find that, as over-densities grow over cosmic time, the inner region becomes heavily screened.