Zobrazeno 1 - 10
of 25
pro vyhledávání: '"de Carvalho, J. P. M."'
We expand previous works on the spherical `top-hat' collapse (SC-TH) framework in generalized Chaplygin gas (gCg) dominated universes. Here we allow the collapse in all energetic components within the system. We analyze the non-linear stages of colla
Externí odkaz:
http://arxiv.org/abs/1110.6205
Publikováno v:
Phys.Rev.D78:067302,2008
We discuss the possible dynamical role of extended cosmic defects on galactic scales, specifically focusing on the possibility that they may provide the dark matter suggested by the classical problem of galactic rotation curves. We emphasize that the
Externí odkaz:
http://arxiv.org/abs/0807.4373
Publikováno v:
JCAP 0309:002,2003
We explicitly demonstrate that, contrary to recent claims, the dynamics of a generalized Chaplygin gas model with an equation of state $p=-C$ (where $C$ is a positive constant) is equivalent to that of a standard $\Lambda$CDM model to first order in
Externí odkaz:
http://arxiv.org/abs/astro-ph/0307427
Publikováno v:
Phys.Rev.D69:041301,2004
We discuss the onset of the non-linear regime in the context of unified dark matter models involving a generalised Chaplygin gas. We show that the transition from dark matter-like to dark energy-like behaviour will never be smooth. In some regions of
Externí odkaz:
http://arxiv.org/abs/astro-ph/0306493
Publikováno v:
Phys.Rev. D67 (2003) 101301
We discuss the importance of including baryons in analyses of unified dark matter scenarios, focusing on toy models involving a generalized Chaplygin gas. We determine observational constraints on this unified dark matter scenario coming from large s
Externí odkaz:
http://arxiv.org/abs/astro-ph/0303564
Publikováno v:
Phys.Rev. D67 (2003) 023511
We discuss the issue of toy model building for the dark energy component of the universe. Specifically, we consider two generic toy models recently proposed as alternatives to quintessence models, known as Cardassian expansion and the Chaplygin gas.
Externí odkaz:
http://arxiv.org/abs/astro-ph/0208528
Publikováno v:
Astropart.Phys. 17 (2002) 367
In a recent article, a simple `spherical bubble' toy model for a spatially varying vacuum energy density was introduced, and type Ia supernovae data was used to constrain it. Here we generalize the model to allow for the fact that we may not necessar
Externí odkaz:
http://arxiv.org/abs/astro-ph/0106245
Publikováno v:
Phys.Rev. D64 (2001) 063505
We consider a very simple toy model for a spatially varying `cosmological constant', where we are inside a spherical bubble (with a given set of cosmological parameters) that is surrounded by a larger region where these parameters are different. This
Externí odkaz:
http://arxiv.org/abs/astro-ph/0103075
Publikováno v:
Phys.Lett.B515:148-154,2001
We show that our Universe may be inhomogeneous on large sub-horizon scales without us being able to realise it. We assume that a network of domain walls permeates the universe dividing it in domains with slightly different vacuum energy densities. We
Externí odkaz:
http://arxiv.org/abs/astro-ph/0004227
Publikováno v:
Phys.Lett. B501 (2001) 257-263
We re-analyze the question of the use of cosmological observations to infer the present state and future evolution of our patch of the universe. In particular, we discuss under which conditions one might be able to infer that our patch will enter an
Externí odkaz:
http://arxiv.org/abs/astro-ph/0002153