Distinguishing cosmologies using the turn-around radius near galaxy clusters

Understand

Outside galaxy clusters the competition between the inwards gravitational attraction and the outwards expansion of the Universe leads to a special radius of velocity cancellation, which is called the turn-around radius.

• Measurements of the turn-around radius hold promises of constraining cosmological parameters, and possibly even properties of gravity.
• Such a measurement is, however, complicated by the fact that the surroundings of galaxy clusters are not spherical, but instead are a complicated collection of filaments, sheets and voids.
• In this paper we use the results of numerically simulated universes to quantify realistic error-bars of the measurement of the turn-around radius.