Origin & evolution of the Universe

Abstract

The aim of this thesis is to question some of the basic assumptions that go into building the $\Lambda$CDM model of our universe. The assumptions we focus on are the initial conditions of the universe, the fundamental forces in the universe on large scales and the approximations made in analysing cosmological data. For each of the assumptions we outline the theoretical understanding behind them, the current methods used to study them and how they can be improved and finally we also perform numerical analysis to quantify the novel solutions/methods we propose to extend the previous assumptions.

arXiv commentDPhil thesis

References in corpus (153)

• Efficient Computation of CMB anisotropies in closed FRW models
• Modified Gravity and Cosmology
• The Confrontation between General Relativity and Experiment
• Cosmological parameters from CMB and other data: a Monte-Carlo approach
• Large scale bias and the peak background split
• Weak Gravitational Lensing
• The Cosmic Linear Anisotropy Solving System (CLASS) II: Approximation schemes
• Ellipsoidal collapse and an improved model for the number and spatial distribution of dark matter haloes
• Tests of general relativity with GW150914
• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang
• Dark Energy Survey Year 1 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
• Cosmological Parameters from Observations of Galaxy Clusters
• An All-Sky Analysis of Polarization in the Microwave Background
• Weak Gravitational Lensing of the CMB
• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• Cosmology and Fundamental Physics with the Euclid Satellite
• Halo occupation numbers and galaxy bias
• Euclid Definition Study Report
• Symmetron Fields: Screening Long-Range Forces Through Local Symmetry Restoration
• Recent Progress in Baryogenesis
• The Dependence of Halo Clustering on Halo Formation History, Concentration, and Occupation
• The linear power spectrum of observed source number counts
• Cosmology from Maxima-1, Boomerang and COBE/DMR CMB Observations
• The Effective Field Theory of Dark Energy
• Determination of Inflationary Observables by Cosmic Microwave Background Anisotropy Experiments
• What galaxy surveys really measure
• Testing General Relativity in Cosmology
• Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity
• Mission design of LiteBIRD
• CFHTLenS: The Canada-France-Hawaii Telescope Lensing Survey - Imaging Data and Catalogue Products
• Weak lensing for precision cosmology
• Fundamental Physics with the Square Kilometre Array
• Effects of Baryons and Dissipation on the Matter Power Spectrum
• Ekpyrotic and Cyclic Cosmology
• CMBPol Mission Concept Study: Probing Inflation with CMB Polarization
• Cosmological Tests of Gravity
• KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering
• Damping of Tensor Modes in Cosmology
• Power Spectrum Super-Sample Covariance
• CosmoLike - Cosmological Likelihood Analyses for Photometric Galaxy Surveys
• Reconstructing the primordial power spectrum
• Non-linear Evolution of f(R) Cosmologies III: Halo Statistics
• Likelihood Analysis of CMB Temperature and Polarization Power Spectra
• Tensor Perturbations in Inflationary Models as a Probe of Cosmology
• Parameter inference with estimated covariance matrices
• Cosmological Constraints from a Combination of Galaxy Clustering and Lensing -- I. Theoretical Framework
• Equivalence Principle Implications of Modified Gravity Models
• The Scientific Programme of Planck
• A Unified Description of Screened Modified Gravity
• The General Primordial Cosmic Perturbation
• N-body Simulations for f(R) Gravity using a Self-adaptive Particle-Mesh Code
• The Separate Universe Approach and the Evolution of Nonlinear Superhorizon Cosmological Perturbations
• Super-Sample Covariance in Simulations
• The impact of baryons on the matter power spectrum from the Horizon-AGN cosmological hydrodynamical simulation
• Systematic Bias in Cosmic Shear: Beyond the Fisher Matrix
• Modified Gravity-GADGET: A new code for cosmological hydrodynamical simulations of modified gravity models
• Cosmic Microwave Background Fluctuations from Gravitational Waves: An Analytic Approach
• How isotropic is the Universe?
• Conserved cosmological perturbations
• On the Prediction of Velocity Fields from Redshift Space Galaxy Samples
• Modified Gravity N-body Code Comparison Project
• On measuring the covariance matrix of the nonlinear power spectrum from simulations
• Exploring Cosmic Origins with CORE: Inflation
• Galaxy Clustering and Galaxy Bias in a Lambda-CDM Universe
• Testing General Relativity on Horizon Scales and the Primordial non-Gaussianity
• Going beyond the Kaiser redshift-space distortion formula: a full general relativistic account of the effects and their detectability in galaxy clustering
• A local resolution of the Hubble tension: The impact of screened fifth forces on the cosmic distance ladder
• COrE (Cosmic Origins Explorer) A White Paper
• Beyond Assembly Bias: Exploring Secondary Halo Biases for Cluster-size Haloes
• Asymmetric galaxy correlation functions
• Constraining Isocurvature Perturbations with CMB Polarization
• Constraining chameleon models with cosmology
• On the assumption of Gaussianity for cosmological two-point statistics and parameter dependent covariance matrices
• Gravitational redshift and other redshift-space distortions of the imaginary part of the power spectrum
• How accurate is Limber's equation?
• Modeling the angular correlation function and its full covariance in Photometric Galaxy Surveys
• Bayesian model selection and isocurvature perturbations
• Estimating Cosmological Parameter Covariance
• Measurement of the dipole in the cross-correlation function of galaxies
• Constraints on a mixed inflaton and curvaton scenario for the generation of the curvature perturbation
• Chameleon Field Theories
• Perfect Quantum Cosmological Bounce
• The angle-averaged squeezed limit of nonlinear matter N-point functions
• Measuring the lensing potential with tomographic galaxy number counts
• Scaling relations and mass bias in hydrodynamical f(R) gravity simulations of galaxy clusters
• Accurate cosmic shear errors: do we need ensembles of simulations?
• Tests of Modified Gravity with Dwarf Galaxies
• Theories of Dark Energy with Screening Mechanisms
• Constraints on isocurvature models from the WMAP first-year data
• The Future of Primordial Features with 21 cm Tomography
• Cosmic Web and Environmental Dependence of Screening: Vainshtein vs. Chameleon
• Massive data compression for parameter-dependent covariance matrices
• Bounds on CDM and neutrino isocurvature perturbations from CMB and LSS data
• Perturbative approach to covariance matrix of the matter power spectrum
• Accounting for Baryons in Cosmological Constraints from Cosmic Shear
• Principal Power of the CMB
• Compensated Isocurvature Perturbations and the Cosmic Microwave Background
• Separate Universe Consistency Relation and Calibration of Halo Bias
• Astrophysical Tests of Modified Gravity: Stellar and Gaseous Rotation Curves in Dwarf Galaxies
• Responses in Large-Scale Structure
• Search for Compensated Isocurvature Perturbations with Planck Power Spectra
• Reconstruction of the Primordial Power Spectrum by Direct Inversion
• A volumetric deep Convolutional Neural Network for simulation of mock dark matter halo catalogues
• Improving the precision matrix for precision cosmology
• Probing gravity with a joint analysis of galaxy and CMB lensing and SDSS spectroscopy
• The Effects of Gravitational Back-Reaction on Cosmological Perturbations
• Baryons do trace dark matter 380,000 years after the big bang: Search for compensated isocurvature perturbations with WMAP 9-year data
• Characterising the Primordial Cosmic Perturbations
• Sample variance in weak lensing: how many simulations are required?
• Gravitational redshifts from large-scale structure
• Quantifying lost information due to covariance matrix estimation in parameter inference
• Measuring cosmic velocities with 21cm intensity mapping and galaxy redshift survey cross-correlation dipoles
• Sensitivity of galaxy cluster dark energy constraints to halo modeling uncertainties
• Reconstructing the gravitational field of the local universe
• Relativistic distortions in the large-scale clustering of SDSS-III BOSS CMASS galaxies
• The modified gravity lightcone simulation project I: Statistics of matter and halo distributions
• Statistical techniques in cosmology
• Biases on the cosmological parameters and thermal SZ residuals
• Gravitational Redshift of Galaxies in Clusters from the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey
• Effects of discontinuities of the derivatives of the inflaton potential
• Estimating the power spectrum covariance matrix with fewer mock samples
• Rogues' gallery: the full freedom of the Bianchi CMB anomalies
• Cosmological Perturbations on a Bouncing Brane
• On estimating cosmology-dependent covariance matrices
• Halo Scale Predictions of Symmetron Modified Gravity
• Large Covariance Matrices: Accurate Models Without Mocks
• Quantum propagation across cosmological singularities
• Simulating galaxy formation in f(R) modified gravity: Matter, halo, and galaxy-statistics
• On the Transfer of Adiabatic Fluctuations through a Nonsingular Cosmological Bounce
• A Bayesian method for combining theoretical and simulated covariance matrices for large-scale structure surveys
• Modifications to Cosmological Power Spectra from Scalar-Tensor Entanglement and their Observational Consequences
• Principal component analysis of the primordial tensor power spectrum
• Lensing signals from Spin-2 perturbations
• Perturbations in a regular bouncing Universe
• Reconstruction of primordial tensor power spectra from B-mode polarization of the cosmic microwave background
• Radiative stability and observational constraints on dark energy and modified gravity
• In search of an observational quantum signature of the primordial perturbations in slow-roll and ultra slow-roll inflation
• Variations of cosmic large-scale structure covariance matrices across parameter space
• On the Effects due to a Decaying Cosmological Fluctuation
• Anisotropic Extinction Distortion of the Galaxy Correlation Function
• Relativistic Effects on Galaxy Redshift Samples due to Target Selection
• Simple Analytical Methods for Computing the Gravity-Wave Contribution to the Cosmic Background Radiation Anisotropy
• Screening maps of the local Universe I -- Methodology
• Primordial Isocurvature Perturbations: Testing the Adiabaticity of the CMB Anisotropy
• Non-Gaussianity from Entanglement During Inflation
• Screened fifth forces in parity-breaking correlation functions
• Quantum Entanglement in Multi-field Inflation
• Initial conditions of the universe: A sign of the sine mode
• Non-local Matching Condition and Scale-invariant Spectrum in Bouncing Cosmology
• Eigen-reconstruction of Perturbations to the Primordial Tensor Power Spectrum
• Relativistic asymmetries in the galaxy cross-correlation function
• Initial conditions of the universe: Decaying tensor modes