New Optimised Estimators for the Primordial Trispectrum (2009)
Munshi, Dipak, Heavens, Alan, Cooray, Asantha, Smidt, Joseph, Coles, Peter, Serra, Paolo
Cosmic microwave background studies of non-Gaussianity involving higher-order multispectra can distinguish between early universe theories that predict nearly identical power spectra. However, the...
Zonal Modes of Cosmic Microwave Background Temperature Maps (2009)
All-sky maps of the cosmic microwave background temperature fluctuations are usually represented by a spherical harmonic decomposition involving modes labelled by their degree $l$ and order $m$...
Adiabatic versus Isocurvature Non--Gaussianity (2009)
Hikage, Chiaki, Munshi, Dipak, Heavens, Alan, Coles, Peter
We study the extent to which one can distinguish primordial non--Gaussianity (NG) arising from adiabatic and isocurvature perturbations. We make a joint analysis of different NG models based on...
Polarized Spots in Anisotropic Open Universes (2009)
We calculate the temperature and polarization patterns generated in anisotropic cosmological models drawn from the Bianchi classification. We show that localized features in the temperature pattern,...
Gravitational Stability of Vortices in Bose-Einstein Condensate Dark Matter (2009)
We investigate a simple model for a galactic halo under the assumption that it is dominated by a dark matter component in the form of a Bose-Einstein condensate involving an ultra-light scalar...
Hikage, Chiaki, Matsubara, Takahiko, Coles, Peter, Liguori, Michele, Hansen, Frode K., Matarrese, Sabino
We present an analysis of the Minkowski Functionals (MFs) describing the WMAP three-year temperature maps to place limits on possible levels of primordial non-Gaussianity. In particular, we apply...
The mystery of the WMAP cold spot (2007)
Naselsky, Pavel D., Christensen, Per Rex, Coles, Peter, Verkhodanov, Oleg, Novikov, Dmitry, Kim, Jaiseung
The first and third year data releases from the WMAP provide evidence of an anomalous Cold Spot (CS) at galactic latitude b=-57deg and longitude l=209deg. We have examined the properties of the CS in...
The Effect of Primordial Non--Gaussianity on the Topology of Large-Scale Structure (2007)
Hikage, Chiaki, Coles, Peter, Grossi, Margherita, Moscardini, Lauro, Dolag, Klaus, Branchini, Enzo, ...
We study the effect of primordial non--Gaussianity on the development of large-scale cosmic structure using high-resolution N-body simulations. In particular, we focus on the topological properties...
Weak Lensing from Strong Clustering (2007)
Dipak Munshi And, Dipak Munshi, Peter Coles
We investigate the effect of weak gravitational lensing in the limit of small angular scales where projected galaxy clustering is strongly nonlinear. This is the regime likely to be probed by future...
Chiang, Lung-Yih, Naselsky, Pavel D., Coles, Peter
The quadrupole power of cosmic microwave background (CMB) temperature anisotropies seen in the WMAP data is puzzlingly low. In this paper we demonstrate that Minimum Variance Optimization (MVO), a...
Scale Transformations, Tree-level Perturbation Theory, and the Cosmological Matter Bispectrum (2007)
Pan, Jun, Coles, Peter, Szapudi, Istvan
Scale transformations have played an extremely successful role in studies of cosmological large-scale structure by relating the non-linear spectrum of cosmological density fluctuations to the linear...
Scale-dependent Galaxy Bias (2007)
We present a simple heuristic model to demonstrate how feedback related to the galaxy formation process can result in a scale-dependent bias of mass versus light, even on very large scales. The model...
Dynamics of a magnetized Bianchi I universe with vacuum energy (2006)
We make use of a flat, axisymmetric Bianchi I metric to investigate the effects of a magnetic field upon the dynamics of the universe for the case in which the accompanying fluid is a cosmological...
Chiang, Lung-Yih, Coles, Peter, Naselsky, Pavel D, Olesen, Poul
We employ the one-dimensional Fourier representation (1DFR) to analyze the 3-year WMAP de-biased internal linear combination (DILC) map and its possible contamination by galactic foregrounds. The...
Chiang, Lung-Yih, Naselsky, Pavel D., Coles, Peter
We test the hypothesis that the temperature of the cosmic microwave background is consistent with a Gaussian random field defined on the celestial sphere, using de-biased internal linear combination...
Multivariate Non-Normality in the WMAP 1st Year Data (2005)
The extraction of cosmological parameters from microwave background observations relies on specific assumptions about the statistical properties of the data, in particular that the p-point...
Amplification of Primordial Magnetic Fields by Anisotropic Gravitational Collapse (2005)
If a magnetic field is frozen into a plasma that undergoes spherical compression then the magnetic field B varies with the plasma density \rho according to B \propto \rho^{2/3}. In the gravitational...
Phase Correlations and Topological Measures of Large-scale Structure (2005)
In these lecture notes I discussed the importance of phase correlations for the morphology of large-scale structure and how phase analysis can probe primordial non-Gaussianity and/or foreground...
Patrick Dineen, Supervisor Prof, Peter Coles, Examiners Prof, Dr. Pedro Ferreira
Thesis submitted to the University of Nottingham
A Faraday Rotation Template for the Galactic Sky (2004)
Using a set of compilations of measurements for extragalactic radio sources we construct all-sky maps of the Faraday Rotation produced by the Galactic magnetic field. In order to generate the maps we...
Random-Walk Statistics and the Spherical Harmonic Representation of CMB Maps (2004)
Stannard, Andrew, Coles, Peter
We investigate the properties of the (complex) coefficients obtained in a spherical harmonic representation of temperature maps of the cosmic microwave background (CMB). We study the effect of the...
Large-scale Structure with the SKA (2004)
A standard theoretical paradigm for the formation of large-scale structure in the distribution of galaxies has now been established, based on the gravitational instability of cold dark matter in a...
Non-Random Phases in Non-Trivial Topologies (2004)
Dineen, Patrick, Rocha, Graca, Coles, Peter
We present a new technique for constraining the topology of the universe. The method exploits the existence of correlations in the phases of the spherical harmonic coefficients of the CMB temperature...
Phase Correlations in Cosmic Microwave Background Temperature Maps (2003)
Coles, Peter, Dineen, Patrick, Earl, John, Wright, Dean
We study the statistical properties of spherical harmonic modes of temperature maps of the cosmic microwave background. Unlike other studies, which focus mainly on properties of the amplitudes of...
Faraday Rotation as a Diagnostic of Galactic Foreground Contamination of CMB Maps (2003)
We present a diagnostic test of possible Galactic contamination of cosmic microwave background sky maps designed to provide an independent check on the methods used to compile these maps. The method...
A Wave-Mechanical Approach to Cosmic Structure Formation (2002)
The dynamical equations describing the evolution of a self-gravitating fluid can be rewritten in the form of a Schrodinger equation coupled to a Poisson equation determining the gravitational...
Universal Behavior of Phase Correlations in Non-linear Gravitational Clustering (2002)
Watts, Peter, Coles, Peter, Melott, Adrian
The large-scale structure of the Universe is thought to evolve by a process of gravitational amplification from low-amplitude Gaussian noise generated in the early Universe. The later, non-linear...
The Wave Mechanics of Large-scale Structure (2002)
I review the basic ``gravitational instability'' model for the growth of structure in the expanding Universe. This model requires the existence of small initial irregularities in the density of a...
Statistical Properties of Cosmological Fluctuations (2002)
In this pedagogical lecture, I introduce some of the basic terminology and description of fluctuating fields as they occur on cosmology. I define various statistical, cosmological and sample...
Statistical Cosmology with Quadratic Density Fields (2002)
Primordial fluctuations in the cosmic density are usually assumed to take the form of a Gaussian random field that evolves under the action of gravitational instability. In the early stages, while...
Phase Mapping as a Powerful Diagnostic of Primordial Non-Gaussianity (2002)
Chiang, Lung-Yih, Naselsky, Pavel, Coles, Peter
The identification and extraction of non-Gaussian signals is one of the main cosmological challenges facing future experimental measurements of the cosmic microwave background temperature pattern. We...
Return mapping of phases and the analysis of the gravitational clustering hierarchy (2002)
Chiang, Lung-Yih, Coles, Peter, Naselsky, Pavel
In the standard paradigm for cosmological structure formation, clustering develops from initially random-phase (Gaussian) density fluctuations in the early Universe by a process of gravitational...
University of Nottingham, (2002)
Abstract. In this pedagogical lecture, I introduce some of the basic terminology and description of fluctuating fields as they occur on cosmology. I define various statistical, cosmological and...
Boundary Corrections in Fractal Analysis of Galaxy Surveys (2001)
The analysis of redshift surveys with fractal tools requires one to apply some form of statistical correction for galaxies lying near the geometric boundary of the sample. In this paper we compare...
The Origin of Spatial Intermittency in the Galaxy Distribution (2001)
The dynamical equations describing the evolution of a self-gravitating fluid can be rewritten in the form of a Schrodinger equation coupled to a Poisson equation determining the gravitational...
Large-Scale Structure, Theory and Statistics (2001)
I review the standard paradigm for understanding the formation and evolution of cosmic structure, based on the gravitational instability of dark matter, but many variations on this basic theme are...
Einstein, Eddington and the 1919 Eclipse (2001)
The modern era of cosmology began with the publication of Einstein's general theory of relativity in 1915. The first experimental test of this theory was Eddington's famous expedition to measure the...
Non-linearity and Non-Gaussianity through Phase Information (2000)
Coles, Peter, Chiang, Lung-Yih
In the standard picture of structure formation, initially random-phase fluctuations are amplified by non-linear gravitational instability to produce a final distribution of mass which is highly...
Large-scale Cosmic Homogeneity from a Multifractal Analysis of the PSCz Catalogue (2000)
We investigate the behaviour of galaxy clustering on large scales using the PSCz catalogue. In particular, we ask whether there is any evidence of large-scale fractal behaviour in this catalogue. We...
Characterizing the non-linear growth of large-scale structure in the Universe (2000)
Coles, Peter, Chiang, Lung-Yih
The local Universe displays a rich hierarchical pattern of galaxy clusters and superclusters. The early Universe, however, was almost smooth, with only slight 'ripples' seen in the cosmic microwave...
Error Estimates for Measurements of Cosmic Shear (2000)
In the very near future, weak lensing surveys will map the projected density of the universe in an unbiased way over large regions of the sky. In order to interpret the results of studies it is...
Cosmic Statistics through Weak Lenses (2000)
Many recent studies have demonstrated that scaling arguments, such as the so-called hierarchical {\em ansatz}, are extremely useful in understanding the statistical properties of weak gravitational...
Weak Lensing from Strong Clustering (1999)
We investigate the effect of weak gravitational lensing in the limit of small angular scales where projected galaxy clustering is strongly nonlinear. This is the regime likely to be probed by future...
Phase Information and the Evolution of Cosmological Density Perturbations (1999)
Chiang, Lung-Yih, Coles, Peter
The Fourier transform of cosmological density perturbations can be represented in terms of amplitudes and phases for each Fourier mode. We investigate the phase evolution of these modes using a...
Bias and Hierarchical Clustering (1999)
Coles, Peter, Melott, Adrian, Munshi, Dipak
It is now well established that galaxies are biased tracers of the distribution of matter, although it is still not known what form this bias takes. In local bias models the propensity for a galaxy...
Munshi, Dipak, Coles, Peter, Melott, Adrian L.
We develop a diagrammatic technique to represent the multi-point cumulative probability density function (CPDF) of mass fluctuations in terms of the statistical properties of individual collapsed...
Munshi, Dipak, Coles, Peter, Melott, Adrian L.
The highly nonlinear regime of gravitational clustering is characterized by the presence of scale-invariant form of many-body correlation functions. Useful insights can be obtained by investigating...
Munshi, Dipak, Coles, Peter, Melott, Adrian L.
The highly nonlinear regime of gravitational clustering is characterized by the presence of scale-invariant form of many-body correlation functions. Useful insights can be obtained by investigating...
Generalised Cumulant Correlators and Hierarchical Clustering (1998)
Munshi, Dipak, Melott, Adrian L., Coles, Peter
The cumulant correlators, $C_{pq}$, are statistical quantities that generalise the better-known $S_p$ parameters; the former are obtained from the two-point probability distribution function of the...
The Clustering of Lyman-break Galaxies (1998)
Coles, Peter, Lucchin, Francesco, Matarrese, Sabino, Moscardini, Lauro
We calculate the statistical clustering of Lyman-break galaxies predicted in a selection of currently-fashionable structure formation scenarios. These models are all based on the cold dark matter...
The Bull's-Eye Effect as a Probe of $\Omega$ (1998)
Melott, Adrian L., Coles, Peter, Feldman, Hume A., Wilhite, Brian
We compare the statistical properties of structures normal and transverse to the line of sight which appear in theoretical N-body simulations of structure formation, and seem also to be present in...
Modelling galaxy clustering at high redshift (1997)
Moscardini, Lauro, Coles, Peter, Lucchin, Francesco, Matarrese, Sabino
We discuss the theoretical interpretation of observational data concerning the clustering of galaxies at high redshifts. Building on the theoretical machinery developed by Matarrese et al. (1997), we...
Redshift evolution of clustering (1996)
Matarrese, Sabino, Coles, Peter, Lucchin, Francesco, Moscardini, Lauro
We discuss how the redshift dependence of the observed two-point correlation function of various classes of objects can be related to theoretical predictions. This relation involves first a...
Large-Scale Structure in Mixed Dark Matter Models with a Non-thermal Volatile Component (1996)
Pierpaoli, Elena, Coles, Peter, Bonometto, Silvio, Borgani, Stefano
We investigate the properties of large--scale structure predicted in a class of mixed dark matter models in which the volatile component (made of particles with high rms velocity) derives from the...
Quantifying the Topology of Large-Scale Structure (1996)
Coles, Peter, Davies, Andrew G., Pearson, Russell C.
We propose and investigate a new algorithm for quantifying the topological properties of cosmological density fluctuations. We first motivate this algorithm by drawing a formal distinction between...
The Cluster Distribution as a Test of Dark Matter Models. III. the Cluster Velocity Field (1995)
Moscardini, Lauro, Branchini, Enzo, Brunozzi, Paolo Tini, Borgani, Stefano, Plionis, Manolis, Coles, Peter
We study the large-scale velocity fields traced by galaxy clusters in numerical simulations of a box of side 960 $h^{-1}$ Mpc, and compare them with available data on real clusters. In order to test...
Getting the Measure of the Flatness Problem (1995)
Evrard, Guillaume, Coles, Peter
The problem of estimating cosmological parameters such as $\Omega$ from noisy or incomplete data is an example of an inverse problem and, as such, generally requires a probablistic approach. We adopt...
Approximation Methods for Non-linear Gravitational Clustering (1995)
We discuss various analytical approximation methods for following the evolution of cosmological density perturbations into the strong (i.e. nonlinear) clustering regime. These methods can be...
Testing DM models against the cluster distribution (1995)
Plionis, Manolis, Borgani, Stefano, Moscardini, Lauro, Coles, Peter
We study the clustering properties of numerical simulations of the cluster distribution, which are based on the Zel'dovich approximation, and compare them with an extended redshift sample of...
Abstract. The problem of estimating cosmological parameters such as � from noisy or incomplete data is an example of inverse problems and, as such, generally requires a probabilistic approach. We...
Pharmacological analysis of cannabinoid receptor activity in the rat vas deferens
Christopoulos, Arthur, Coles, Peter, Lay, Lucy, Lew, Michael J, Angus, James A
The interaction between the cannabinoid agonists, WIN 55,212-2 or CP 55,940 with the CB1 receptor-selective antagonists, SR141716A or LY320135 was investigated using the rat electrically-stimulated...