Largescale Structure of the Universe

2004

In these notes I will review our present understanding of the origin and evolution of the universe, making emphasis on the most recent observations of the acceleration of the universe, the precise measurements of the microwave background anisotropies, and the formation of structure like galaxies and clusters of galaxies from tiny primodial fluctuations generated during inflation. 1

2013

The next generation of telescopes will usher in a new era of precision cosmology capable of determining key parameters of a cosmological model to percent level and beyond. For this to be effective, the theoretical model must be understood to at least the same level of precision. A range of subtle physical spacetime effects remain to be explored theoretically, for example, the effect of backreaction on cosmological observables. A good understanding of this effect is paramount given that it is a consequence of any space-time theory of gravity. We provide a comprehensive study of this effect from the perspective of geometric averaging on a hyper-surface and averaging on the celestial sphere. We concentrate on Friedmann-Lemaitre-Robertson-Walker spacetime with small perturbation up to non-linear order. This enables us to quantify by how much this effect could change the standard model interpretation of the universe. We study in great detail key parameters of the standard model, Hubble rate, deceleration parameter and area distance. We find that the Hubble rate depends on the choice of definition of the Hubble rate and the spatial surface on which the average is performed. Within the ΛCDM model, the backreaction effect on the background Hubble rate is of order 1% at a scale of 100 Mpc, and much less on larger scales. We find that for the deceleration parameter adapted to observation, the perturbation theory gives divergent answers in the UV and corrections to the background are of order unity or more depending on the choice of UV cutoff. For the area distance, we identify a range of new lensing effects, which include: double-integrated and nonlinear integrated Sach-Wolfe contributions, transverse Doppler effects in redshift space distortions, lensing from the induced vector mode and gravitational wave backgrounds, in addition to lensing from the secondorder potential and we also identify a new double-coupling between the density fluctuations integrated along the line of sight, and gradients in the density fluctuations coupled to transverse velocities along the line of sight. We conclude that the precision cosmology would be unsuccessful without the effect of backreaction being properly taking into account in parameter estimation. Also we need to rethink our theoretical approach to sub-horizon universe because un-renormalized perturbation theory appear not to be working. I would like to thank Camille Bonvin and Ruth Durrer for useful technical discussions on area distance in cosmology. I appreciate a detailed email clarifying the technical subtleties associated with switching of averaging hyper-surface by Giovanni Marozzi. I would also like to thank Gabriele Veneziano and his collaborators for comments on the first draft of the area distance paper. I would like to thank Alex Weigand and Dominik Schwarz for comments on the fitting formula for the averaged Hubble rate and the relationship with their work. I appreciate discussion with Albert Stebbins on constructing observable quantities. I also owe a special thanks to my office mate and friend Sean February for discussion and proofreading part of the thesis. I am grateful to Cyril Pitrou and JP Uzan for discussions on many aspects of this work and other unpublished works. I am very grateful to Sean Hartnoll for saving me from self-destruction during my Msc studies and after. I am highly indebted to Astrophysics section of department of Physics Oxford University for hospitality during the time I spent with them. I appreciate every special assistance given to me especially by Pedro Ferreira , Tim Clifton, Phil Bull, Sarah White, Krzysztof Bolejko, Edward Macaulay, and all the graduate students in the group. I would like to thank in a special way my supervisors: Chris Clarkson and George F. R. Ellis for both academic and personal guidance and assistance. I owe a special thanks to George for reading through every paragraph of this thesis. I am very grateful for this. Most of the computations here were done with the help of the tensor algebra package xPert/xAct [1] and xPand which I developed in collaboration with Cyril Pitrou and Xavier Roy.

Physical Review D, 2004

We revise the statistical properties of the primordial cosmological density anisotropies that, at the time of matter radiation equality, seeded the gravitational development of large scale structures in the, otherwise, homogeneous and isotropic Friedmann-Robertson-Walker flat universe. Our analysis shows that random fluctuations of the density field at the same instant of equality and with comoving wavelength shorter than the causal horizon at that time can naturally account, when globally constrained to conserve the total mass (energy) of the system, for the observed scale invariance of the anisotropies over cosmologically large comoving volumes. Statistical systems with similar features are generically known as glass-like or lattice-like. Obviously, these conclusions conflict with the widely accepted understanding of the primordial structures reported in the literature, which requires an epoch of inflationary cosmology to precede the standard expansion of the universe.

Australian Journal of Physics, 1990

A review of recent developments in the study of the structure of the universe is given. We focus on two problems: the fractal description of the universe, and on observational constraints on the bias in galaxy formation.

The Structure and Composition of Cosmos, 2022

The Structure and Composition of Cosmos consists of two theories: the Quantum Ether Theory (QET) and the Euclidean Cosmos Theory (ECT), where the Quantum Ether Theory forms the basis for the Euclidean Cosmos Theory, which derives the composition of the Cosmos. Taken together, the two theories provide a description of the Cosmos and the universes that fits the observations of our Universe and makes it possible to understand how it all works. The theories explain how the Cosmos, the universes and everything we know is the result of the properties of the zero-point field, that is, the theories explain how the vacuum permittivity (ε_0), the vacuum permeability (µ_0) and their properties - like Planck’s constant (h), the frequency (f), the elementary charge (e), the universal gravitational constant (G) and the derived fine structure constant (α) - creates the wave-particles, the mass of the particles, the forces and their pro-pagation, as well as the distribution of the total amount of matter in the Cosmos. The Quantum Ether Theory finds, based on the properties of space and time, that space is Euclidean and that the relativistic laws are the result of a speed in relation to the final constant propagation speed of the forces in the zero-point field (ZPF). Furthermore, the theory holds that the electric and magnetic properties of the zero-point field can explain the presence of all the physical properties and relationships present in the Cosmos. The Euclidean Cosmos Theory finds the distribution of mass and energy in the infinite Euclidean space. Since m = E/c^2, both mass and energy will be deflected in a gravitational field, so that the mass and energy eventually accumulate in closed universes and barren objects, all of which are in some form of dynamic equilibrium; unless the average energy density of the zero-point field is so high that there will only be one large coherent universe, which occurs when the density is about 5.9 hydrogen atoms per cubic meters. If the universes are not to end up as barren objects, they must have a size that enables them to create regenerative processes, which are defined as processes, that transforms heavier substances into lighter ones, which, for instance, occurs in the active galactic nuclei (AGNs); which, together with the stars, are responsible for the formation of the cosmic background radiation (CMB) and the nebulae from which the stars are born. As a result of the ceaseless regenerative processes, the density of the universes is very sparse, as can be seen from the density of our own Universe. Based on this density, it is possible to make an estimate of the size of the universes, which will be practically the same for all the universes that have reached the maximum size at the given density; for when a universe has reached the maximum size for a closed universe, it will not be able to retain additional material. Inside the universes, gravity and the regenerative processes impart a density distribution to the universes, where the density gradually decreases with distance from the center of the universe. The Quantum Ether theory reintroduces the ether as a consequence of Maxwell’s equations, as well as WMAP and Stefan Marinov’s measurements of the absolute velocity relative to the zero-point field (ZPF). Since the electromagnetic forces and gravity propagate in the zero-point field at the finite constant speed of light, the relativistic contractions occur when bodies bound together by one of these forces have a velocity relative to the field and thus relative to the constant rate of propagation of the forces that bind the bodies together. Thus, relativity and the related phenomena can be derived on the basis of classical physics, so QET derives a relativistic version of Coulomb’s law and Newton’s law, as well as length contraction, relativistic mass and relativistic gravity. On the basis of these laws it can also be proven that time is absolute and universal, with which space is Euclidean. The Euclidean Cosmos Theory holds that since the zero-point field is infinite, the average energy density contained in the zero-point field must, by the law of conservation of energy, also be infinite; and since space is Euclidean, the Cosmos must always have existed and consist of an infinitely flat space where the infinite amount of mass and energy resides. Due to gravity, the mass and energy will have accumulated in closed universes, black holes and barren bodies, all of which are in some form of dynamic equilibrium. However, even the closed universes will eventually end up as barren objects if the black holes were unable to distribute their mass and energy by regenerative processes; where a regenerative process is defined as a process that converts heavier elements into lighter ones; and since the cosmological redshift consists mainly of a plasma-induced redshift that arises as a result of the photons’ transfer of energy to the plasma, the universes are seen to be static. In each of the closed universes, gravity causes most of the mass and energy to end up as galaxies, which consist mainly of dark matter in the form of black dwarfs, neutron stars and black holes. This is because the Cosmos has always existed, and it only takes about 0.08 solar masses to create a black dwarf, 1.4 solar masses to create a neutron star, and between 3 and 8 solar masses to create a black hole, depending on the saturation density of the nuclear material. In each of the universes there will be a life cycle of energy, where the stars and the black holes in the center of the galaxies create the greatest regenerative processes when the matter concentration becomes sufficiently high. The regenerative processes thus supply energy to the cycle of matter and radiation in the universe, where the new energy often ends up as nebulae or cosmic background radiation. The nebulae are the first step on the way to stars, red giants, white dwarfs, supernovae, neutron stars and black holes, where the energy again gathers in the center of the galaxy. Since the cosmic background radiation reflects the regenerative processes, it in a way reflects the structure of the universes with their great walls and gigantic voids, which are created on the basis of the law of least effort. Finally, the theory calculates the order of magnitude of the energy production from the black holes in the center of galaxies, and explains how mass and energy escape from the black holes.

2005

Presentamos un resumen de nuestro trabajo sobre estructuras del Universo en diferentes estados de agregación, poniendo especialénfasis en el estudio de cúmulos de galaxias con alto corrimienro al rojo. El mismo comprende el análisis de unos 7 grados cuadrados usando imágenes profundas con varios filtrosópticos anchos. Planeamos complementarlos con observaciones en el infrarrojo cercano con telescopios de 4 m. Los resultados preliminares de nuestro análisis en un campo de 35x35 minutos de arco indican la detección de varios candidatos a cúmulos con corrimiento al rojo mayor que 0.5. Cuando finalizemos el análisis de todos los campos dispondremos de una muestra adecuada para estudios detallados con GTC.

2003

With the recent measurements of temperature and polarization anisotropies in the microwave background by WMAP, we have entered a new era of precision cosmology, with the cosmological parameters of a Standard Cosmological Model determined to 1%. This Standard Model is based on the Big Bang theory and the inflationary paradigm, a period of exponential expansion in the early universe responsible for the large-scale homogeneity and spatial flatness of our observable patch of the Universe. The spectrum of metric perturbations, seen in the microwave background as temperature anisotropies, were produced during inflation from quantum fluctuations that were stretched to cosmological size by the expansion, and later gave rise, via gravitational collapse, to the observed large-scale structure of clusters and superclusters of galaxies. Furthermore, the same theory predicts that all the matter and radiation in the universe today originated at the end of inflation from an explosive production of particles that could also have been the origin of the present baryon asymmetry, before the universe reached thermal equilibrium at a very large temperature. From there on, the universe cooled down as it expanded, in the way described by the standard hot Big Bang model.

Lecture Notes in Physics, 2009

Australian Journal of Physics, 1990

Implications of the observed large scale structure on the physics of the early universe are described. A short review of Soviet work on the subject is given, and the present status of the fractal model of the large scale structure is discussed.

2008

A summary of the Workshop NOVICOSMO 2008. held in SISSA, Trieste, 20-23 October 2008.

The SDSS galaxy catalog is one of the best databases for galaxy distribution studies. The SDSS DR8 data is used to construct the galaxy cluster catalog. We construct the clusters from the calculated luminosity density field and identify denser regions. Around these peak regions we construct galaxy clusters. Another interesting question in cosmology is how observable galaxy structures are connected to underlying dark matter distribution. To study this we compare the SDSS DR7 galaxy group catalog with galaxy groups obtained from the semi-analytical Millennium N-Body simulation. Specifically, we compare the group richness, virial radius, maximum separation and velocity dispersion distributions and find a relatively good agreement between the mock catalog and observations. This strongly supports the idea that the dark matter distribution and galaxies in the semi-analytical models and observations are very closely linked.

An introduction to modern theories for the origin of structure in the Universe is given. After a brief review of the growth of cosmological perturbations in an expanding Universe and a summary of some important observational results, the lectures focus on the inflationary Universe scenario and on topological defect models of structure formation. A summary of the theory and current observational status of cosmic microwave background temperature fluctuations is given. The final chapter is devoted to some speculative ideas concerning the connection between cosmology and fundamental physics, in particular to ways in which the singularity problem of classical cosmology may be resolved.

2020

In this paper, we will analyze the effects of expansion on the large scale structure formation in our universe. This will be done by incorporating a cosmological constant term in the gravitational partition function. This gravitational partition function with a cosmological constant would be used for analyzing the thermodynamics for this system. We will analyze the viral expansion for this system, and obtain its equation of state. It is observed that the equation of state is the Van der Waals equation. We also analyze a gravitational phase transition in this system. This will be done using the mean field theory for this system. We construct the cosmic energy equation for this system of galaxies, and compare it with observational data. We also analyze the distribution function for this system, and compare it with the observational data.

viXra, 2017

A new cosmological model is proposed for the dynamics of the Universe and the formation and evolution of galaxies. It is shown that the matter of the Universe contracts and expands in cycles, and that galaxies in a particular cycle may have imprints from the previous cycle. It is proposed that RHIC’s liquid gets trapped in the cores of galaxies in the beginning of each cycle and is liberated throughout time and is, thus, the power engine of AGNs. It is also proposed that the large-scale structure is a permanent property of the Universe, and thus, it is not created. It is proposed that spiral galaxies and elliptical galaxies are formed by mergers of nucleon vortices (vorteons) at the time of the big squeeze and immediately afterwards and that the merging process, in general, lasts an extremely long time, of many billion years. The origin of quasars is explained and the evaporation rate of RHIC’s liquid is calculated. The large mass at the center of quasar PDS 456 is calculated and ag...