Results for "Shaun Cole"

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Adding Long-Wavelength Power to N-body SimulationsApr 10 1996Sep 06 1996Tormen and Bertschinger have presented an algorithm which allows the dynamic range of N-body simulations to be extended by adding long-wavelength power to an evolved N-body simulation. This procedure is of considerable interest as it will enable mock ... More
Maximum Likelihood Random Galaxy Catalogues and Luminosity Function EstimationMar 31 2011Jun 03 2011We present a new algorithm to generate a random (unclustered) version of an magnitude limited observational galaxy redshift catalogue. It takes into account both galaxy evolution and the perturbing effects of large scale structure. The key to the algorithm ... More
Modelling Galaxy Merger Timescales and Tidal DestructionSep 29 2016We present a model for the dynamical evolution of subhaloes based on an approach combining numerical and analytical methods. Our method is based on tracking subhaloes in an N-body simulation up to the last point that it can be resolved, and applying an ... More
The Structure of Dark Matter Haloes in Hierarchical Clustering ModelsOct 30 1995Mar 08 1996We use a set of large cosmological N-body simulations to study the internal structure of dark matter haloes which form in scale-free models. We find that the radius r_178 corresponding to a mean interior overdensity of 178 accurately delineates the quasi-static ... More
Constraints on the identity of the dark matter from strong gravitational lensesDec 21 2015Apr 05 2016The cold dark matter (CDM) cosmological model unambigously predicts that a large number of haloes should survive as subhaloes when they are accreted into a larger halo. The CDM model would be ruled out if such substructures were shown not to exist. By ... More
Cosmological Constraints from applying SHAM to rescaled cosmological simulationsFeb 04 2013We place constraints on the matter density of the Universe and the amplitude of clustering using measurements of the galaxy two-point correlation function from the Sloan Digital Sky Survey (SDSS). We generate model predictions for different cosmologies ... More
Merger rates in hierarchical models of galaxy formation. II: Comparison with N-body simulationsFeb 28 1994May 24 1994We have made a detailed comparison of the results of large N-body simulations with the analytical description of the merging histories of dark matter halos presented in Lacey & Cole 1993, which is based on an extension of the Press- Schechter method (Bond ... More
Globular clusters vs dark matter haloes in strong lensing observationsJul 06 2017Small distortions in the images of Einstein rings or giant arcs offer the exciting prospect of detecting dark matter haloes or subhaloes of mass below $10^9$M$_{\odot}$, most of which are too small to have made a visible galaxy. A very large number of ... More
The galaxy power spectrum: precision cosmology from large scale structure?Aug 13 2007Dec 05 2007Published galaxy power spectra from the 2dFGRS and SDSS are not in good agreement. We revisit this issue by analyzing both the 2dFGRS and SDSS DR5 catalogues using essentially identical techniques. We confirm that the 2dFGRS exhibits relatively more large ... More
The redshift dependence of the structure of massive LCDM halosNov 06 2007Apr 02 2008(Abridged) We use two very large cosmological simulations to study how the density profiles of relaxed LCDM dark halos depend on redshift and on halo mass. We confirm that these profiles deviate slightly but systematically from the NFW form and are better ... More
Halo concentrations from extended Press-Schechter merger historiesDec 14 2018We apply the model relating halo concentration to formation history proposed by Ludlow et al. to merger trees generated using an algorithm based on excursion set theory. We find that while the model correctly predicts the median relation between halo ... More
Physical constraints on the central mass and baryon content of satellite galaxiesNov 10 2009Recent analysis of the Milky Way's satellite galaxies reveals that these objects share a common central mass density, even though their luminosities range over five orders of magnitude. This observation can be understood in the context of galaxy formation ... More
The Galaxy Power Spectrum: 2dFGRS-SDSS tension?Nov 06 2006Published galaxy power spectra from the 2dFGRS and SDSS are not in good agreement. We revisit this issue by analyzing both the 2dFGRS and SDSS DR5 catalogues using essentially identical technqiues. We confirm that the 2dFGRS exhibits relatively more large ... More
Constraints on sigma_8 from galaxy clustering in N-body simulations and semi-analytic modelsSep 21 2007We generate mock galaxy catalogues for a grid of different cosmologies, using rescaled N-body simulations in tandem with a semi-analytic model run using consistent parameters. Because we predict the galaxy bias, rather than fitting it as a nuisance parameter, ... More
Massive Dark Matter Halos around Bright Isolated Galaxies in the 2dFGRSOct 29 2007We identify a large sample of isolated bright galaxies and their fainter satellites in the 2dF Galaxy Redshift Survey (2dFGRS). We analyse the dynamics of ensembles of these galaxies selected according to luminosity and morphological type by stacking ... More
The formation of shell galaxies similar to NGC 7600 in the cold dark matter cosmogonyNov 11 2011We present new deep observations of 'shell' structures in the halo of the nearby elliptical galaxy NGC 7600, alongside a movie of galaxy formation in a cold dark matter universe (available at http://www.virgo.dur.ac.uk/shell-galaxies). The movie, based ... More
Cluster mass reconstruction from weak gravitational lensingJan 19 1996Kaiser & Squires have proposed a technique for mapping the dark matter in galaxy clusters using the coherent weak distortion of background galaxy images caused by gravitational lensing. We investigate the effectiveness of this technique under controlled ... More
Generating Dark Matter Halo Merger TreesAug 10 2007Nov 22 2007We present a new Monte-Carlo algorithm to generate merger trees describing the formation history of dark matter halos. The algorithm is a modification of the algorithm of Cole et al (2000) used in the GALFORM semi-analytic galaxy formation model. As such, ... More
Constraining Omega using weak gravitational lensing by clustersJan 22 1996The morphology of galaxy clusters reflects the epoch at which they formed and hence depends on the value of the mean cosmological density, Omega. Recent studies have shown that the distribution of dark matter in clusters can be mapped from analysis of ... More
Achieving Convergence in Galaxy Formation Models by Augmenting N-body Merger TreesApr 07 2016Aug 16 2016Accurate modeling of galaxy formation in a hierarchical, cold dark matter universe requires the use of sufficiently high-resolution merger trees to obtain convergence in the predicted properties of galaxies. When semi-analytic galaxy formation models ... More
Instabilities in Granular FlowJul 14 2000We consider the stability of a system of equations which are a singular perturbation of the incompressible rigid-plastic flow equations used to model granular flow. A linear stability analysis shows that solutions of these equations are unstable, in general, ... More
Symplectic quotients by a nonabelian group and by its maximal torusJan 01 2000This paper examines the relationship between the symplectic quotient X//G of a Hamiltonian G-manifold X, and the associated symplectic quotient X//T, where T is a maximal torus, in the case in which X//G is a compact manifold or orbifold. The three main ... More
The evolution of the stellar mass versus halo mass relationshipOct 28 2015Nov 04 2015We present an analysis of the predictions made by the Galform semi-analytic galaxy formation model for the evolution of the relationship between stellar mass and halo mass. We show that for the standard implementations of supernova feedback and gas reincorporation ... More
Semi-analytical galaxy formation models and the high redshift universeOct 23 1998Semi-analytical models of galaxy formation based on hierarchical clustering now make a wide range of predictions for observable properties of galaxies at low and high redshift. This article concentrates on 2 aspects: (1) Self-consistent modelling of dust ... More
A marked correlation function analysis of halo formation times in the Millennium SimulationOct 17 2005Mar 29 2006We study the environmental dependence of the formation epoch of dark matter haloes in the Millennium Simulation: a ten billion particle N-body simulation of standard LambdaCDM cosmology. A sensitive test of this dependence - the marked correlation function ... More
Towards accurate modelling of the ISW effect, the non-linear contributionSep 25 2008Mar 13 2009In a universe with a cosmological constant, the large-scale gravitational potential varies in time and this is, in principle, observable. Using an N-body simulation of a $\Lambda$CDM universe, we show that linear theory is not sufficiently accurate to ... More
The orbital PDF: the dynamical state of Milky Way sized haloes and the intrinsic uncertainty in the determination of their massesJul 02 2015Nov 29 2015Using realistic cosmological simulations of Milky Way sized haloes, we study their dynamical state and the accuracy of inferring their mass profiles with steady-state models of dynamical tracers. We use a new method that describes the phase-space distribution ... More
N-body Dark Matter Haloes with simple Hierarchical HistoriesNov 26 2013Feb 28 2014We present a new algorithm which groups the subhaloes found in cosmological N- body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly hierarchical. One advantage of these `Dhaloes' over the ... More
Star formation trends in high-redshift galaxy surveys: the elephant or the tail?Nov 11 2010Nov 29 2010Star formation rate and accummulated stellar mass are two fundamental physical quantities that describe the evolutionary state of a forming galaxy. Two recent attempts to determine the relationship between these quantities, by interpreting a sample of ... More
Constraining the WDM Particle Mass with Milky Way SatellitesOct 29 2013Well-motivated particle physics theories predict the existence of particles (such as sterile neutrinos) which acquire non-negligible thermal velocities in the early universe. These particles could behave as warm dark matter (WDM) and generate a small-scale ... More
Recovering dark-matter clustering from galaxies with GaussianizationNov 06 2015The Gaussianization transform has been proposed as a method to remove the issues of scale-dependent galaxy bias and nonlinearity from galaxy clustering statistics, but these benefits have yet to be thoroughly tested for realistic galaxy samples. In this ... More
What to expect from dynamical modelling of galactic haloesMay 30 2016Jul 27 2017Many dynamical models of the Milky Way halo require assumptions that the distribution function of a tracer population should be independent of time (i.e., a steady state distribution function) and that the underlying potential is spherical. We study the ... More
The orbital PDF: general inference of the gravitational potential from steady-state tracersJul 02 2015Dec 04 2015We develop two general methods to infer the gravitational potential of a system using steady-state tracers, i.e., tracers with a time-independent phase-space distribution. Combined with the phase-space continuity equation, the time independence implies ... More
Full-sky map of the ISW and Rees-Sciama effect from Gpc simulationsMar 04 2010Mar 16 2010We present a new method for constructing maps of the secondary temperature fluctuations imprinted on the cosmic microwave background (CMB) radiation by photons propagating through the evolving cosmic gravitational potential. Large cosmological N-body ... More
Satellite Galaxy Number Density Profiles in the Sloan Digital Sky SurveyJan 05 2012Sep 05 2012We study the spatial distribution of satellite galaxies around isolated primaries using the Sloan Digital Sky Survey (SDSS) spectroscopic and photometric galaxy catalogues. We select isolated primaries from the spectroscopic sample and search for potential ... More
The Evolution of Galaxy Clustering in Hierarchical ModelsOct 13 1999The main ingredients of recent semi-analytic models of galaxy formation are summarised. We present predictions for the galaxy clustering properties of a well specified LCDM model whose parameters are constrained by observed local galaxy properties. We ... More
Using the Evolution of Clusters to Constrain OmegaJan 16 1996The population of rich galaxy clusters evolves much more rapidly in a universe with critical density than one with low density, thus offering the possibility of determining the cosmological density parameter, Omega_0. We quantify this evolution using ... More
Mock 2dF and SDSS galaxy redshift surveysJan 26 1998Jun 26 1998We present a comprehensive set of mock 2dF and SDSS galaxy redshift surveys constructed from a set of large, high-resolution cosmological N-body simulations. The radial selection functions and geometrical limits of the catalogues mimic those of the genuine ... More
Constraints onOmega from the IRAS Redshift SurveysDec 17 1994We measure the anisotropy of the redshift-space power spectrum in the 1.2-Jy and QDOT redshift surveys of IRAS-selected galaxies. On large scales, this anisotropy is caused by coherent peculiar motions, and gravitational instability theory predicts a ... More
A unified model for the spatial and mass distribution of subhaloesSep 07 2015Dec 08 2015N-body simulations suggest that the substructures that survive inside dark matter haloes follow universal distributions in mass and radial number density. We demonstrate that a simple analytical model can explain these subhalo distributions as resulting ... More
Orbital parameters of infalling satellite haloes in the hierarchical $Λ$CDM modelSep 03 2014Jan 27 2015We present distributions of orbital parameters of infalling satellites of $\Lambda$CDM haloes in the mass range $10^{12}-10^{14}$M$_\odot$, which represent the initial conditions for the subsequent evolution of substructures within the host halo. We use ... More
The Satellite Luminosity Functions of Galaxies in SDSSJan 13 2011Jun 02 2011We study the luminosity function of satellite galaxies around isolated primaries using the Sloan Digital Sky Survey (SDSS) spectroscopic and photometric galaxy samples. We select isolated primaries from the spectroscopic sample and search for potential ... More
The statistical properties of LCDM halo formationAug 10 2007Sep 26 2007We present a comparison of the statistical properties of dark matter halo merger trees extracted from the Millennium Simulation with Extended Press-Schechter (EPS) formalism and the related GALFORM Monte-Carlo method for generating ensembles of merger ... More
Large-scale structure in COBE-normalized cold dark matter cosmogoniesFeb 10 1997We study the clustering of the mass distribution in COBE-normalized open and flat CDM models using large N-body simulations. With an age of the universe of 14 Gyr (12 Gyr) for the flat (open) models and a baryon density fixed by nucleosynthesis constraints, ... More
Hierarchical clustering in chameleon $f(R)$ gravityMay 31 2013We use a suite of high resolution state-of-the-art N-body Dark Matter simulations of chameleon $f(R)$ gravity to study the higher order volume averaged correlation functions $\bar{\xi_n}$ together with the hierarchical $n$-th order correlation amplitudes ... More
The Shapes and Alignments of Dark Matter HalosNov 23 2011Apr 24 2012We present measurements of the triaxial dark matter halo shapes and alignment correlation functions in the Millennium and Millennium-2 dark matter N-body simulations. These two simulations allow us to measure the distributions of halo shapes down to 10% ... More
Fast generation of ensembles of cosmological N-body simulations via mode-resamplingMar 14 2011May 31 2011We present an algorithm for quickly generating multiple realizations of N-body simulations to be used, for example, for cosmological parameter estimation from surveys of large-scale structure. Our algorithm uses a new method to resample the large-scale ... More
Hierarchical Galaxy FormationJul 19 2000We describe the GALFORM semi-analytic model for calculating the formation and evolution of galaxies in hierarchical models. It improves upon, and extends, the Cole et al 1994 model. The model employs a new Monte-Carlo algorithm to follow the merging evolution ... More
Modelling Galaxy Formation at high zSep 17 1997I describe a semi-analytical model for the formation and evolution of galaxies in hierarchical clustering models, and its predictions for the properties of the galaxy population at high z. The predictions are found to agree well with the observed properties ... More
What to expect from dynamical modelling of galactic haloesMay 30 2016Many dynamical models of the Milky Way halo require the assumption that the distribution function of a tracer population should be independent of time (i.e., a steady state distribution function). We study the limitations of such modelling by applying ... More
Fourier Analysis of Redshift Space Distortions and the Determination of OmegaAug 04 1993The peculiar velocities of galaxies distort the pattern of galaxy clustering in redshift space, making the redshift space power spectrum anisotropic. In the linear regime, the strength of this distortion depends only on the ratio $\beta \equiv f(\Omega)/b ... More
Gravitational redshift and asymmetric redshift-space distortions for stacked clustersSep 15 2016We derive the expression for the observed redshift in the weak field limit in the observer's past light cone, including all relativistic terms up to second order in velocity. We then apply it to compute the cluster-galaxy cross-correlation functions (CGCF) ... More
Spatial and luminosity distributions of galactic satellitesJan 14 2013We investigate the luminosity functions (LFs) and projected number density profiles of galactic satellites around isolated primaries of different luminosities. We measure these quantities for model satellites placed into the Millennium and Millennium ... More
On a Linearized Problem Arising in the Navier-Stokes Flow of a Free Liquid JetDec 17 2011In this work, we analyze a Stokes problem arising in the study of the Navier-Stokes flow of a liquid jet. The analysis is accomplished by showing that the relevant Stokes operator accounting for a free surface gives rise to a sectorial operator which ... More
Coupled Optical Resonance Laser LockinJul 09 2013We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to the same spectroscopic sample, by monitoring only the absorption of the UV laser. For trapping and cooling Yb$^{+}$ ions, a frequency stabilized laser is required ... More
Fierz bilinear formulation of the Maxwell-Dirac equations and symmetry reductionsMay 27 2014We study the Maxwell-Dirac equations in a manifestly gauge invariant presentation using only the spinor bilinear scalar and pseudoscalar densities, and the vector and pseudovector currents, together with their quadratic Fierz relations. The internally ... More
Intertwining semisimple characters for quasi-split p-adic classical groups (preliminary version)Mar 31 2015Apr 13 2015Let $G$ be a unitary group of an $\epsilon$-Hermitian form $h$ given over a non-archimedean local field $F$ of residue characteristic not two. Let $V$ be the vector space on which $h$ is defined. Among many other statements about semisimple strata and ... More
Comments on arXiv:1310.5067: "A response to `A self-consistent public catalogue of voids and superclusters in the SDSS Data Release 7 galaxy surveys' "Oct 25 2013Nov 11 2013Sutter et al. have responded to the criticisms we made of their cosmic void catalogue in our recent paper presenting an alternative catalogue (Nadathur & Hotchkiss 2013). Unfortunately, their response contains several statements which are incorrect, as ... More
A Variant on the Feline Josephus ProblemMar 30 2018In the Feline Josephus problem, soldiers stand in a circle, each having $\ell$ `lives'. Going around the circle, a life is taken from every $k$th soldier; soldiers with 0 lives remaining are removed from the circle. Finding the last surviving soldier ... More
Genericity of supercuspidal representations of p-adic Sp(4)Aug 20 2007We describe the supercuspidal representations of Sp(4,F), for F a non-archimedean local field of residual characteristic different from 2, and determine which are generic.
Representations lisses de GL(m,D), IV : representations supercuspidalesJul 12 2006Let F be a non Archimedean locally compact field and let D be a central F-division algebra. We prove that any positive level supercuspidal irreducible representation of the group GL(m,D) is compactly induced from a representation of a compact mod center ... More
Symmetric Homology of AlgebrasAug 11 2007Nov 05 2007In this note, we outline the general development of a theory of symmetric homology of algebras, an analog of cyclic homology where the cyclic groups are replaced by symmetric groups. This theory is developed using the framework of crossed simplicial groups ... More
Cuspidal $\ell$-modular representations of $p$-adic classical groupsSep 07 2015Nov 26 2015For a classical group over a non-archimedean local field of odd residual characteristic p, we construct all cuspidal representations over an arbitrary algebraically closed field of characteristic different from p, as representations induced from a cuspidal ... More
The small scale power asymmetry in the cosmic microwave backgroundJul 23 2013Sep 27 2013We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l=601-2048, with a naive statistical significance of 6.5 sigma. However, we show ... More
Mating quadratic maps with the modular group IINov 16 2016In 1994 S. Bullett and C. Penrose introduced the one complex parameter family of $(2:2)$ holomorphic correspondences $\mathcal{F}_a$: $$\left(\frac{aw-1}{w-1}\right)^2+\left(\frac{aw-1}{w-1}\right)\left(\frac{az+1}{z+1}\right) +\left(\frac{az+1}{z+1}\right)^2=3$$ ... More
Symmetric Homology of AlgebrasFeb 07 2009Jun 23 2011The symmetric homology of a unital algebra $A$ over a commutative ground ring $k$ is defined using derived functors and the symmetric bar construction of Fiedorowicz. For a group ring $A = k[\Gamma]$, the symmetric homology is related to stable homotopy ... More
A Construction on Operads Applicable to Homology Operations and the Minimal ModelAug 14 2015We define a construction on operads which yields a new description of the minimal model. The construction also allows us to define algebraic structures on the homology of chain complexes with homologously trivial operad algebra structures, thus exposing ... More
Graph Labeling with Distance Conditions and the Delta Squared ConjectureSep 01 2013Nov 07 2013We give bounds on the L(2,1)-labeling number of a simple graph in terms of its order and its maximum degree. We also describe an infinite class of graphs of which the elements have the highest L(2,1)-labeling numbers in terms of their maximum degrees ... More
The Wave Mechanics of Large-scale StructureSep 27 2002I 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 largely uniform universe. These grow through linear and ... More
Einstein, Eddington and the 1919 EclipseFeb 27 2001The 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 bending of light at a total solar eclipse in 1919. So ... More
A New Estimate of the Hubble Time with Improved Modeling of Gravitational LensesFeb 21 2008This paper examines free-form modeling of gravitational lenses using Bayesian ensembles of pixelated mass maps. The priors and algorithms from previous work are clarified and significant technical improvements are made. Lens reconstruction and Hubble ... More
A simplified disproof of Beck's three permutations conjecture and an application to root-mean-squared discrepancyNov 02 2018Nov 27 2018A $k$-permutation family on $n$ vertices is a set system consisting of the intervals of $k$ permutations of the integers $1$ through $n$. The discrepancy of a set system is the minimum over all red-blue vertex colorings of the maximum difference between ... More
Precise asymptotics for Fisher-KPP frontsDec 07 2017We consider the one-dimensional Fisher-KPP equation with step-like initial data. Nolen, Roquejoffre, and Ryzhik showed that the solution $u$ converges at long time to a traveling wave $\phi$ at a position $\tilde \sigma(t) = 2t - (3/2)\log t + \alpha_0- ... More
Large-scale Structure with the SKAAug 24 2004A 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 background cosmology dominated by vacuum energy. Significant ... More
The Origin of Spatial Intermittency in the Galaxy DistributionOct 29 2001The 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 potential. This approach has a number of interesting features, ... More
Large-Scale Structure, Theory and StatisticsMar 01 2001I 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 viable. Despite the great progress that has undoubtedly ... More
Phase Correlations and Topological Measures of Large-scale StructureFeb 04 2005In 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 contamination in CMB temperature maps. I illustrate the ideas ... More
Statistical Properties of Cosmological FluctuationsSep 27 2002In 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 homogeneity and explain what is meant by the fair sample hypothesis ... More
Circuit Relations for Real Stabilizers: Towards TOF+HApr 24 2019The real stabilizer fragment of quantum mechanics was shown to have a complete axiomatization in terms of the angle-free fragment of the ZX-calculus. This fragment of the ZXcalculus--although abstractly elegant--is stated in terms of identities, such ... More
Counting paths in corridors using circular Pascal arraysJul 08 2014A circular Pascal array is a periodization of the familiar Pascal's triangle. Using simple operators defined on periodic sequences, we find a direct relationship between the ranges of the circular Pascal arrays and numbers of certain lattice paths within ... More
The Clustering Evolution of Dusty Star-Forming GalaxiesApr 17 2015May 05 2016We present predictions for the clustering of galaxies selected by their emission at far infra-red (FIR) and sub-millimetre wavelengths. This includes the first predictions for the effect of clustering biases induced by the coarse angular resolution of ... More
Blending bias impacts the host halo masses derived from a cross-correlation analysis of bright sub-millimetre galaxiesAug 16 2016Placing bright sub-millimetre galaxies (SMGs) within the broader context of galaxy formation and evolution requires accurate measurements of their clustering, which can constrain the masses of their host dark matter halos. Recent work has shown that the ... More
The Properties of Spiral Galaxies: Confronting Hierarchical Galaxy Formation Models with ObservationsMar 24 2003Apr 11 2003We compare the properties of local spiral galaxies with the predictions of the Cole et al. semi-analytic model of hierarchical galaxy formation, in order to gain insight into the baryonic processes that were responsible for shaping these galaxies. On ... More
The evolution of the star forming sequence in hierarchical galaxy formation modelsMar 06 2014Aug 26 2014It has been argued that the specific star formation rates of star forming galaxies inferred from observational data decline more rapidly below z = 2 than is predicted by hierarchical galaxy formation models. We present a detailed analysis of this problem ... More
Mock galaxy redshift catalogues from simulations: implications for Pan-STARRS1Oct 13 2008Dec 22 2008We describe a method for constructing mock galaxy catalogues which are well suited for use in conjunction with large photometric surveys. We use the semi-analytic galaxy formation model of Bower et al. implemented in the Millennium simulation. We apply ... More
Estimating the dark matter halo mass of our Milky Way using dynamical tracersFeb 11 2015Oct 27 2015The mass of the dark matter halo of the Milky Way can be estimated by fitting analytical models to the phase-space distribution of dynamical tracers. We test this approach using realistic mock stellar halos constructed from the Aquarius N-body simulations ... More
Blending bias impacts the host halo masses derived from a cross-correlation analysis of bright sub-millimetre galaxiesAug 16 2016Apr 20 2017Placing bright sub-millimetre galaxies (SMGs) within the broader context of galaxy formation and evolution requires accurate measurements of their clustering, which can constrain the masses of their host dark matter halos. Recent work has shown that the ... More
Creating mock catalogues of stellar haloes from cosmological simulationsJun 09 2014Oct 28 2014We present a new technique for creating mock catalogues of the individual stars that make up the accreted component of stellar haloes in cosmological simulations and show how the catalogues can be used to test and interpret observational data. The catalogues ... More
Comparing semi-analytic particle tagging and hydrodynamical simulations of the Milky Way's stellar haloNov 10 2016Aug 17 2017Particle tagging is an efficient, but approximate, technique for using cosmological N-body simulations to model the phase-space evolution of the stellar populations predicted, for example, by a semi-analytic model of galaxy formation. We test the technique ... More
A Possible Cold Imprint of Voids on the Microwave Background RadiationJan 25 2013Feb 18 2014We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0<z<0.44$. We find an imprint of amplitude between 2.6 and 2.9$\mu ... More
The Properties of Spiral Galaxies in Semi-Analytic Galaxy Formation ModelsAug 16 2000We examine the present-day galaxy disk colors and star formation rates (SFRs) in the semi-analytic model of Cole et al. (2000). We find that the fiducial model is a good match to Kennicutt's (1998) observed global star formation law, the color-based metallicity-magnitude ... More
Formation of In Situ Stellar Haloes in Milky Way-Mass GalaxiesJan 19 2015Oct 04 2015We study the formation of stellar haloes in three Milky Way-mass galaxies using cosmological smoothed particle hydrodynamics simulations, focusing on the subset of halo stars that form in situ, as opposed to those accreted from satellites. In situ stars ... More
Cluster correlation functions in N-body simulationsFeb 19 1996The correlation function of galaxy clusters has often been used as a test of cosmological models. A number of assumptions are implicit in the comparison of theoretical expectations to data. Here we use an ensemble of ten large N-body simulations of the ... More
Galaxy Formation in a Variety of Hierarchical ModelsAug 18 1994We predict the observable properties of the galaxy population in popular hierarchical models of galaxy formation. We employ a detailed semianalytic procedure which incorporates the formation and merging of dark matter halos, the shock heating and radiative ... More
How common is the Milky Way - satellite system alignment?May 11 2009The highly flattened distribution of satellite galaxies in the Milky Way presents a number of puzzles. Firstly, its polar alignment stands out from the planar alignments commonly found in other galaxies. Secondly, recent proper motion measurements reveal ... More
Satellite Systems around Galaxies in Hydrodynamic SimulationsJul 11 2006We investigate the properties of satellite galaxies formed in N-body/SPH simulations of galaxy formation in the $\Lambda$CDM cosmology. The simulations include the main physical effects thought to be important in galaxy formation and, in several cases, ... More
Projection effects in the strong lensing study of subhaloesDec 19 2016The defining characteristic of the cold dark matter (CDM) hypothesis is the presence of a very large number of low-mass haloes, too small to have made a visible galaxy. Other hypotheses for the nature of the dark matter, such as warm dark matter (WDM), ... More
Simulated observations of sub-millimetre galaxies: the impact of single-dish resolution and field varianceJun 03 2014Oct 24 2014Recent observational evidence suggests that the coarse angular resolution ($\sim20"$ FWHM) of single-dish telescopes at sub-mm wavelengths has biased the observed galaxy number counts by blending together the sub-mm emission from multiple sub-mm galaxies ... More
What to expect from dynamical modelling of galactic haloes II: the spherical Jeans equationJan 23 2018Mar 13 2018The spherical Jeans equation (SJE) is widely used in dynamical modelling of the Milky Way (MW) halo potential. We use haloes and galaxies from the cosmological Millennium-II simulation and hydrodynamical APOSTLE simulations to investigate the performance ... More
The Integrated Sachs-Wolfe effect in $f(R)$ gravityOct 25 2013Feb 18 2014We study the late-time Integrated Sachs-Wolfe (ISW) effect in $f(R)$ gravity using N-body simulations. In the $f(R)$ model under study, the linear growth rate is larger than that in general relativity (GR). This slows down the decay of the cosmic potential ... More