English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Cosmological backreaction suggests a link between structure formation and theexpansion history of the Universe. In order to quantitatively examine thisconnection, we dynamically investigate a volume partition of the Universe intoover-- and underdense regions. This allows us to trace structure formationusing the volume fraction of the overdense regions $\lambda_{\CM}$ as itscharacterizing parameter. Employing results from cosmological perturbationtheory and extrapolating the leading mode into the nonlinear regime, weconstruct a three--parameter model for the effective cosmic expansion history,involving $\lambda_{\CM_{0}}$, the matter density $\Omega_{m}^{\CD_{0}}$, andthe Hubble rate $H_{\CD_{0}}$ of today's Universe. Taking standard values for$\Omega_{m}^{\CD_{0}}$ and $H_{\CD_{0}}$ as well as a reasonable value for$\lambda_{\CM_{0}}$, that we derive from $N$--body simulations, we determinethe corresponding amounts of backreaction and spatial curvature. We find thatthe obtained values that are sufficient to generate today's structure also leadto a $\Lambda$CDM--like behavior of the scale factor, parametrized by the sameparameters $\Omega_{m}^{\CD_{0}}$ and $H_{\CD_{0}}$, but without a cosmologicalconstant. However, the temporal behavior of $\lambda_{\CM}$ does not faithfullyreproduce the structure formation history. Surprisingly, however, the modelmatches with structure formation with the assumption of a low matter content,$\Omega_{m}^{\CD_{0}}\approx3\%$, a result that hints to a differentinterpretation of part of the backreaction effect as kinematical Dark Matter.(truncated)

Multiscale cosmology and structure-emerging Dark Energy: A plausibility analysis