Zobrazeno 1 - 10
of 78
pro vyhledávání: '"Oliver F. Piattella"'
Autor:
Emmanuel Frion, David Camarena, Leonardo Giani, Tays Miranda, Daniele Bertacca, Valerio Marra, Oliver F. Piattella
Publikováno v:
The Open Journal of Astrophysics, Vol 7 (2024)
Externí odkaz:
https://doaj.org/article/c9251bc67c2c45b893f47a8c41006e73
Publikováno v:
Physics Letters B, Vol 798, Iss , Pp - (2019)
We study the John term of Fab Four cosmology in the presence of a scalar potential. We show here how this theory can describe a wide range of cosmological solutions. This theory has two general functions of the scalar field: the potential V(ϕ) and t
Externí odkaz:
https://doaj.org/article/207aa8a7f51b48d8bc6f0377c3070099
Autor:
Kirill A. Bronnikov, Júlio C. Fabris, Oliver F. Piattella, Denis C. Rodrigues, Edison C. Santos
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 77, Iss 6, Pp 1-9 (2017)
Abstract The k-essence theory with a power-law function of $$(\partial \phi )^2$$ ( ∂ ϕ ) 2 and Rastall’s non-conservative theory of gravity with a scalar field are shown to have the same solutions for the metric under the assumption that both t
Externí odkaz:
https://doaj.org/article/69767a841ecf406ab742387702581e97
Publikováno v:
Universe, Vol 5, Iss 10, p 213 (2019)
We review the features of Dark Matter as a particle, presenting some old and new instructive models, and looking for their physical implications in the early universe and in the process of structure formation. We also present a schematic of Dark Matt
Externí odkaz:
https://doaj.org/article/8e276cfe10534145a99442642a52f669
Autor:
Oliver F. Piattella
Publikováno v:
Universe, Vol 2, Iss 4, p 25 (2016)
We analyse the effect of the cosmological expansion on the deflection of light caused by a point mass, adopting the McVittie metric as the geometrical description of a point-like lens embedded in an expanding universe. In the case of a generic, non-c
Externí odkaz:
https://doaj.org/article/77fc74c23d844b0d94e47f1e31ab4ebf
Publikováno v:
The European Physical Journal Plus. 138
Rastall introduced a stress-energy tensor whose divergence is proportional to the gradient of the Ricci scalar. This proposal leads to a change in the form of the field equations of General Relativity, but it preserves the number of degrees of freedo
Autor:
Pedro Bessa, Oliver F. Piattella
We extend the results obtained in \cite{Piattella_2016, mcvittie_2015} and \cite{Park_2008} for gravitational lensing in the McVittie metric by including the effect of the transition from the matter-dominated epoch of the Universe to the $\Lambda$-do
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::526d6c1ec8cf7c3ca5cfdddfa19b2955
Autor:
Oliver F. Piattella
Publikováno v:
Cadernos de Astronomia. 1:30-39
Apresentamos aqui uma breve e não-técnica introdução à teoria da relatividade geral, começando pelo conceito de espaço-tempo, passando pelo princípio de equivalência, e chegando nos testes clássicos que consagraram a teoria como uma das mai
We study how the evolution of a Dark Energy Quintessence fluid is modified by the presence of a matter inhomogeneity. To do so, we study linear perturbations of a flat FLRW background containing dust and a slowly rolling scalar field. Under the assum
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b40388f241e43e0a4d0eb311c8dc78df