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arXiv · 1906.04748

Distinguishing cosmologies using the turn-around radius near galaxy clusters

Steen H. Hansen·Farbod Hassani·Lucas Lombriser·Martin Kunz
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Abstract

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. We find that for a $\Lambda$CDM cosmology these error-bars are typically of the order of $20\%$. We numerically simulate three different implementations of dark energy models and of a scalar dark sector interaction to address whether the turn-around radius can be used to constrain non-trivial cosmologies, and we find that only rather extreme models can be distinguished from a $\Lambda$CDM universe due to the large error-bars arising from the non-trivial cluster environments.

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Steen H. Hansen, Farbod Hassani, Lucas Lombriser, Martin Kunz. 2019-06-11. Distinguishing cosmologies using the turn-around radius near galaxy clusters. https://doi.org/10.1088/1475-7516/2020/01/048

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