We consider a spherical thick 3-brane immersed in a five-dimensional bulk spacetime. We demonstrate how the thick brane equation of motion expanded in powers of the thickness of the brane can be obtained from the expected junction conditions on the boundaries of thick brane with the two embedding spacetimes. It is shown that the finite thickness leads to a faster collapse of the spherical shell...

Choptuik has demonstrated that naked singularities can arise in gravitational collapse from smooth, asymptotically flat initial data, and that such data have codimension one in spherical symmetry. Here we show, for perfect fluid matter with equation of state p = ρ/3, by perturbing around spherical symmetry, that such data have in fact codimension one in the full phase space, at least in a neigh...

Assuming the weak energy condition, we study the nature of the non-central shell-focussing singularity which can form in the gravitational collapse of a spherical compact object in classical general relativity. We show that if the radial pressure is positive, the singularity is covered by a horizon. For negative radial pressures, the singularity will be covered if the ratio of pressure to the d...

I explain the motivation of my thesis work and briefly review the relevant background. In the standard paradigm, galaxies are formed within dark matter halos and merge with each other after halo aggregation. In the first part, I briefly summarize the currently favored cosmological models, I introduce linear perturbation theory and I illustrate non-linear evolution with a spherical collapse mode...

The spherical collapse model was first developed by Gunn & Gott 1 for a flat universe with no cosmological constant. It assumes that the process of formation of bound objects in the universe can be at first approximation described by evolution of an uniformly overdense spherical region in otherwise smooth background. Despite its simplicity, the model has been widely used to explain properties o...

The delivery of suspended active ingredients to a surface is a central function of numerous commercial cosmetic, drug, and agricultural formulations. Many products use liquid droplets as a delivery vehicle but, because interfacial tension keeps droplets spherical, these materials cannot exploit the benefits of anisotropic shape and shape change offered by solid colloids. In this work, individua...

We present a new open-source, user-friendly toolkit of two codes$-$SFcollapse1D and NRPyCritCol$-$to study critical phenomena in the context gravitational collapse. SFcollapse1D is C/C++ tool designed to solve problem collapse massless, spherically symmetric scalar fields with ADM formalism spherical-like coordinates. NRPyCritColis collection Python modules that leverage NRPy+ infrastructure ge...

Dynamical collapse and fragmentation of low-metallicity cloud cores is studied using three-dimensional hydrodynamical calculations, with particular attention devoted whether the cores fragment in the dust-cooling phase or not. The cores become elongated in this phase, being unstable to non-spherical perturbation due to the sudden temperature decrease. In the metallicity range of 10−6 − 10Z⊙, co...