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

We investigate the virialization of cosmic structures in the framework offlat FLRW cosmological models, in which the vacuum energy density evolves withtime. In particular, our analysis focuses on the study of spherical matterperturbations, as they decouple from the background expansion, "turn around"and finally collapse. We generalize the spherical collapse model in the casewhen the vacuum energy is a running function of the Hubble rate,$\Lambda=\Lambda(H)$. A particularly well motivated model of this type is theso-called quantum field vacuum, in which $\Lambda(H)$ is a quadratic function,$\Lambda(H)=n_0+n_2\,H^2$, with $n_0\neq 0$. This model was previously studiedby our team using the latest high quality cosmological data to constrain itsfree parameters, as well as the predicted cluster formation rate. It turns outthat the corresponding Hubble expansion history resembles that of thetraditional $\Lambda$CDM cosmology. We use this $\Lambda(t)$CDM framework toillustrate the fact that the properties of the spherical collapse model (virialdensity, collapse factor, etc.) depend on the choice of the considered vacuumenergy (homogeneous or clustered). In particular, if the distribution of thevacuum energy is clustered, then, under specific conditions, we can producemore concentrated structures with respect to the homogeneous vacuum energycase.

The spherical collapse model in time varying vacuum cosmologies