Zobrazeno 1 - 10
of 112
pro vyhledávání: '"Winfried Zimdahl"'
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 77, Iss 7, Pp 1-10 (2017)
Abstract Both scalar fields and (generalized) Chaplygin gases have been widely used separately to characterize the dark sector of the universe. Here we investigate the cosmological background dynamics for a mixture of both these components and quanti
Externí odkaz:
https://doaj.org/article/389353d6206b4d01929335a4e15449cc
Publikováno v:
Universe, Vol 5, Iss 3, p 68 (2019)
Extensions of Einstein’s General Relativity (GR) can formally be given a GR structure in which additional geometric degrees of freedom are mapped on an effective energy-momentum tensor. The corresponding effective cosmic medium can then be modeled
Externí odkaz:
https://doaj.org/article/b058b35488734d72847eca0393c19751
Autor:
Alexander B. Balakin, Winfried Zimdahl
Publikováno v:
Entropy, Vol 4, Iss 3, Pp 49-64 (2002)
Abstract: Introducing an effective refraction index of an isotropic cosmic medium, we investigate the cosmological fluid dynamics which is consistent with a conformal, timelike symmetry of a corresponding "optical" metric. We demonstrate that this ki
Externí odkaz:
https://doaj.org/article/63e8886e35dd40b38efb585e51ffc1aa
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 80, Iss 12, Pp 1-10 (2020)
European Physical Journal
European Physical Journal
Models with non-gravitational interactions between the dark matter and dark energy components are an alternative to the standard cosmological scenario. These models are characterized by an interaction term, and a frequently used parameterization is $
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9827fbf00030bc525050aa4fa82b4afc
https://doaj.org/article/e041c40a1baf424d832370f5b527220c
https://doaj.org/article/e041c40a1baf424d832370f5b527220c
Autor:
Winfried Zimdahl
This paper tries to obtain a simple picture of several aspects of the mode structure in relativistic non-equilibrium thermodynamics. Its pedagogical focus is on the relation between long-wavelength perturbation modes of the causal M\"{u}ller-Israel-S
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::385500bbeb7482c43f523476932ebda4
http://arxiv.org/abs/2110.00975
http://arxiv.org/abs/2110.00975
We study an expanding two-fluid model of non-relativistic dark matter and radiation which are allowed to interact during a certain time span and to establish an approximate thermal equilibrium. Such interaction which generates an effective bulk visco
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::90846d3947d8332549a0bfa9091c9320
Autor:
Hermano Velten, Winfried Zimdahl
Publikováno v:
Cadernos de Astronomia. 3:151
Apresenta-se uma tradução do alemão, do artigo seminal de Alexander Friedmann publicado em 1922, onde encontram-se as bases de um modelo cosmológico dinâmico.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::64a2ba24d42bae9e788d2c0f0fb0e2ad
https://doi.org/10.47456/cad.astro.v3n1.37322
https://doi.org/10.47456/cad.astro.v3n1.37322
Publikováno v:
Physics of the Dark Universe. 15:114-124
Yes, but only for a parameter value that makes it almost coincide with the standard model. We reconsider the cosmological dynamics of a generalized Chaplygin gas (gCg) which is split into a cold dark matter (CDM) part and a dark energy (DE) component
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::40af41b9a2fa2b0bdc18da7afa3d0ecb
https://doi.org/10.1016/j.dark.2017.02.001
https://doi.org/10.1016/j.dark.2017.02.001
The current Universe is composed by a mixture of relativistic species, baryonic matter, dark matter and dark energy which evolve in a non-trivial way at perturbative level. An advanced description of the cosmological dynamics should include non-stand
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::31c15068ecccd8f4507b9a93cc9fbd27
http://arxiv.org/abs/1911.12084
http://arxiv.org/abs/1911.12084
Autor:
Winfried Zimdahl
Publikováno v:
Cadernos de Astronomia. 2:106
Os dados observacionais atuais indicam que aproximadamente 95% do substrato cosmológico é invisível e só se manifesta através de sua ação gravitacional. A conclusão mais aceita, baseada na teoria da relatividade geral de Einstein, é
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b05752a483fb22455b0642120f9cc757
https://doi.org/10.47456/cad.astro.v2n1.33624
https://doi.org/10.47456/cad.astro.v2n1.33624