10 papers
Spherical `Top-Hat' Collapse in general Chaplygin gas dominated universes
R. A. A. Fernandes, J. P. M. de Carvalho, A. Yu. Kamenshchik +2
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 c…
Dark matter from cosmic defects on galactic scales?
N. Guerreiro, P. P. Avelino, J. P. M. de Carvalho +1
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 th…
Alternatives to Quintessence Model Building
P. P. Avelino, L. M. G. Beca, J. P. M. de Carvalho +2
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 quin…
CMB constraints on spatial variations of the vacuum energy density
P. P. Avelino, A. Canavezes, J. P. M. de Carvalho +1
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…
Supernova constraints on spatial variations of the vacuum energy density
P. P. Avelino, J. P. M. de Carvalho, C. J. A. P. Martins
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 su…
Can our Universe be inhomogeneous on large sub-horizon scales ?
P. P. Avelino, J. P. M. de Carvalho, C. J. A. P. Martins +1
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 divi…