Related papers: Cosmic strings, domain walls and environment-depen…
We describe the results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. For models with $\Gamma = \Omega h = 0.1 - 0.2$ and a cold dark matter…
A novel mechanism to produce a cosmic network of fundamental superstrings based on a time-varying string tension has been recently proposed. It has been found that fundamental superstrings can grow in a kinating background driven by the…
The Standard Model is the low-energy limit of a microscopic theory which includes extra dimensions and new symmetries. A part of my thesis consisted in constructing a new class of models with two extra dimensions. We showed that these…
The search for cosmic strings has been of renewed interest with the advent of precision cosmology. In this note we give a quantitative description of the nonlinear matter density fluctuations that can form from a scaling network of cosmic…
We explore local consequences of a non-zero cosmological constant on astrophysical structures. We find that the effects are not only sensitive to the density of the configurations but also to the geometry. For non-homogeneous…
We examine the possibility of "soft cosmology", namely small deviations from the usual framework due to the effective appearance of soft-matter properties in the Universe sectors. One effect of such a case would be the dark energy to…
The effect of background dynamics of the universe on formation of large scale structures in the framework of Modified Newtonian Dynamics (MOND) is investigated. A spherical collapse model is used for modeling the formation of the…
It is known than the inclusion of spatial curvature can modify the evolution of matter perturbations and affect the Large Scale Structure (LSS) formation. We quantify the effects of the non-zero space curvature in terms of LSS formation for…
Growing Neutrino quintessence describes a form of dynamical dark energy that could explain why dark energy dominates the universe only in recent cosmological times. This scenario predicts the formation of large scale neutrino lumps which…
The gravitationally-driven evolution of cold dark matter dominates the formation of structure in the Universe over a wide range of length scales. While the longest scales can be treated by perturbation theory, a fully quantitative…
We consider a cosmology in which dark matter and a quintessence scalar field responsible for the acceleration of the Universe are allowed to interact. Allowing for both conformal and disformal couplings, we perform a global analysis of the…
Dark energy has a dramatic effect on the dynamics of the universe, causing the recently discovered acceleration of the expansion. The dynamics are also central to the behavior of the growth of large scale structure, offering the possibility…
We investigate some classical aspects of fundamental strings via numerical experiments. In particular, we study the thermodynamics of a string network within a toroidal universe, as a function of string energy density and space…
We propose a new non-minimally coupled quintessence model to account for the late-time dark energy dynamics indicated by recent DESI measurements. Within this framework, the quintessence density begins to decrease only when it starts to…
In this paper we present the results of $N$-body simulations with a scalar field coupled differently to cold dark matter (CDM) and baryons. The scalar field potential and coupling function are chosen such that the scalar field acquires a…
Long-range attractive fifth forces can lead to exponential instabilities in the early Universe. For fermions with a Yukawa coupling to a sufficiently light scalar mediator, rapid oscillations of the scalar field can lead to a conservative…
In this paper we investigate the impact of the coupling between a quintessence field and clustered matter on the average equation of state of the scalar field. We take the NFW profile to be characteristic of bound structures on galactic and…
We propose and implement a novel test to assess deviations from well-established concordance $\Lambda$CDM cosmology while inferring dark energy properties. In contrast to the commonly implemented parametric forms of the dark energy…
We study the nonlinear evolution of density perturbations in cosmologies where the late-time accelerated expansion is driven by a quintessence field with vanishing speed of sound. For these models matter and quintessence perturbations are…
We consider a generic type of dark energy fluid, characterised by a constant equation of state parameter w and sound speed c_s, and investigate the impact of dark energy clustering on cosmic structure formation using the spherical collapse…