相关论文: Domain Wall Dominated Universes
It is well known that the spontaneous breaking of discrete symmetries may lead to conflict with big-bang cosmology. This is due to formation of domain walls which give unacceptable contribution to the energy density of the universe. On the…
As cosmology has entered a phase of precision experiments, the content of the universe has been established to contain interesting and not yet fully understood components, namely dark energy and dark matter. While the cause and exact nature…
We investigate the possibility that part of the dark matter is not made out of the usual cold dark matter (CDM) dustlike particles, but is under the form of a fluid of strings with barotropic factor $w_s = -1/3$ of cosmic origin. To this…
Modern cosmology successfully deals with the origin and the evolution of the Universe at large scales, but it is unable to completely answer the question about the nature of the fundamental objects that it is describing. As a matter of…
The Universe on large scales is well described by the Lambda-CDM cosmological model. There however remain some heavy clouds on our global understanding, especially on galaxy scales, which we review here. While some of these clouds might…
We propose an explanation for the dark matter-baryon coincidence based on collapsing $\mathbb{Z}_N$ domain walls, which form a novel compact baryonic state: the baryoid. A baryoid has an asteroid-scale mass and up-to-nuclear-scale energy…
Nearly seventy per cent of the energy density in the universe is unclustered and exerts negative pressure. This conclusion -- now supported by numerous observations -- poses the greatest challenge for theoretical physics today. I discuss…
Dark Matter might be an accidentally stable baryon of a new confining gauge interaction. We extend previous studies exploring the possibility that the DM is made of dark quarks heavier than the dark confinement scale. The resulting…
The dark side of the universe is mysterious and its nature is still unknown. In fact, this poses perhaps as the biggest challenge in the modern cosmology. The two components of the dark sector (dark matter and dark energy) correspond today…
To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/\rho <-1/3$. This…
In the generic CDM cosmogony, dark-matter halos emerge too lumpy and centrally concentrated to host observed galactic disks. Moreover, disks are predicted to be smaller than those observed. We argue that the resolution of these problems may…
Cosmological observations strongly suggest the presence of dark energy which comprises the majority of the current energy density of the universe. The equation of state relating the pressure and energy density of this dark energy, p = w…
It is shown that late-time decay of domain walls can dilute unwanted relics such as moduli, if the universe was dominated by frustrated domain walls with tension $\sigma = (1 - 100 TeV)^3$. Since energy density of the frustrated domain…
Dark energy is the candidate that can produce effective negative pressure and make the galaxies and galaxy clusters move away from each other in an accelerated way. The structures of the Universe have evolved from some initial primordial…
Homogeneous cosmological solutions are obtained in five dimensional space time assuming equations of state $ p = k\rho $ and $ p_{5}= \gamma\rho$ where p is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using…
In astro-ph/0601489, within the framework of the Einsteinian general relativity, we made the observation that if the universe is described by a spatially flat Friedmann-Robertson-Walker (FRW) cosmology with Einsteinian cosmological constant…
In the framework of noncompact Kaluza-Klein theory, we investigate a $(4+1)$-dimensional universe consisting of a $(4+1)$ dimensional Robertson-Walker type metric coupled to a $(4+1)$ dimensional energy-momentum tensor. The matter part…
In this paper we study the dynamics of $ n-1$ dimensional domain wall universe embedded in a $n$ dimensional charged dilaton black hole bulk with the non-asymptotically flat and non-asymptotically (A)dS characters. We find that domain wall…
Starting from an inhomogeneous space-time model of the universe we could recreate a scenario of recent time accelerating universe dominated by Dark Energy type of fluid. The background matter component of such a universe was considered to…
We study a number of domain wall forming models where various types of defect junctions can exist. These illustrate some of the mechanisms that will determine the evolution of defect networks with junctions. Understanding these mechanisms…