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589478.pdf (362.64 KB)

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2010-10-12

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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/131710

The spherical collapse model in time varying vacuum cosmologies

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Recurs relacionat

https://doi.org/10.1103/PhysRevD.82.083512

Resum

We investigate the virialization of cosmic structures in the framework of flat Friedmann-Lemaitre-Robertson-Walker cosmological models, in which the vacuum energy density evolves with time. In particular, our analysis focuses on the study of spherical matter perturbations, as they decouple from the background expansion, "turn around," and finally collapse. We generalize the spherical collapse model in the case when the vacuum energy is a running function of the Hubble rate, Λ = Λ ( H ) . A particularly well-motivated model of this type is the so-called quantum field vacuum, in which Λ ( H ) is a quadratic function, Λ ( H ) = n 0 + n 2 H 2 , with n 0 ≠ 0 . This model was previously studied by our team using the latest high quality cosmological data to constrain its free parameters, as well as the predicted cluster formation rate. It turns out that the corresponding Hubble expansion history resembles that of the traditional Λ CDM cosmology. We use this Λ ( t ) CDM framework to illustrate the fact that the properties of the spherical collapse model (virial density, collapse factor, etc.) depend on the choice of the considered vacuum energy (homogeneous or clustered). In particular, if the distribution of the vacuum energy is clustered, then, under specific conditions, we can produce more concentrated structures with respect to the homogeneous vacuum energy case.

Matèries

Col·lapse gravitacional, Cosmologia

Matèries (anglès)

Gravitational collapse, Cosmology

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Articles publicats en revistes (Física Quàntica i Astrofísica)
Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB))

Citació

BASILAKOS, Spyros, PLIONIS, Manolis and SOLÀ PERACAULA, Joan. The spherical collapse model in time varying vacuum cosmologies. Physical Review D. 2010. Vol. D82, num. 8, pags. 113005. ISSN 1550-7998. [consulted: 27 of August of 2026]. Available at: https://hdl.handle.net/2445/131710

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