A Large Sky Simulation of the Gravitational Lensing of the Cosmic Microwave Background

Large scale structure deflects cosmic microwave background (CMB) photons. Since large angular scales in the large scale structure contribute significantly to the gravitational lensing effect, a realistic simulation of CMB lensing requires a sufficiently large sky area. We describe simulations that include these effects, and present both effective and multiple plane ray-tracing versions of the algorithm, which employs spherical harmonic space and does not use the flat sky approximation. We simulate lensed CMB maps with an angular resolution of ~0.9 arcmin. The angular power spectrum of the simulated sky agrees well with analytical predictions. Maps generated in this manner are a useful tool for the analysis and interpretation of upcoming CMB experiments such as PLANCK and ACT.Comment: 14 pages, 12 figures, replaced with version accepted for publication by the AP

The Tree-Particle-Mesh N-body Gravity Solver

The Tree-Particle-Mesh (TPM) N-body algorithm couples the tree algorithm for directly computing forces on particles in an hierarchical grouping scheme with the extremely efficient mesh based PM structured approach. The combined TPM algorithm takes advantage of the fact that gravitational forces are linear functions of the density field. Thus one can use domain decomposition to break down the density field into many separate high density regions containing a significant fraction of the mass but residing in a very small fraction of the total volume. In each of these high density regions the gravitational potential is computed via the tree algorithm supplemented by tidal forces from the external density distribution. For the bulk of the volume, forces are computed via the PM algorithm; timesteps in this PM component are large compared to individually determined timesteps in the tree regions. Since each tree region can be treated independently, the algorithm lends itself to very efficient parallelization using message passing. We have tested the new TPM algorithm (a refinement of that originated by Xu 1995) by comparison with results from Ferrell & Bertschinger's P^3M code and find that, except in small clusters, the TPM results are at least as accurate as those obtained with the well-established P^3M algorithm, while taking significantly less computing time. Production runs of 10^9 particles indicate that the new code has great scientific potential when used with distributed computing resources.Comment: 24 pages including 9 figures, uses aaspp4.sty; revised to match published versio

Characterising Coarse Particle Gangue Densimetric Separation Response in Gold Bearing Sulfide Ore Broken by Different Fine Crushing Modes

The separation behaviour of gangue during densimetric classification and the subsequent inherent propensity to pre-concentrate metal values in gold-bearing sulfide ore is reviewed in this thesis. From this review, the influence of the findings on both interpretative technique and the implied liberation induced by specified crushing mode is reported. This thesis aims to predict preferential grade by density deportment response in gravity separation approaches using metallurgical parameters for value component upgrade and recovery into concentrate

Cosmological Constraints from a Combined Analysis of the Cluster Mass Function and Microwave Background Anisotropies

We present constraints on several cosmological parameters from a combined analysis of the most recent Cosmic Microwave Background anisotropy data and the Sloan Digital Sky Survey cluster mass function. We find that the combination of the two data sets breaks several degeneracies among the parameters and provides the following constraints: $\sigma_8=0.76\pm0.09$, $\Omega_m=0.26^{+0.06}_{-0.07}$, $h=0.66^{+0.05}_{-0.06}$, $n=0.96 \pm 0.05$, $\tau_c=0.07^{+0.07}_{-0.05}$.Comment: 7 pages, 1 figur

The New Testament Concept of Shame

Is the society which gave birth to the New Testament a guilt society or a shame society? Is the function of shame in the New Testament psychological or sociological? To what degree does the sanction of shame determine the behavior and life of the followers of Christ? These are some of the initial questions which aroused interest in carrying out the present study. The function of shame in the early Christian community and its usage in the New Testament does not conform precisely to either the Eastern or the Western view of shame: nor does it merely occupy a mediating middle ground between the two. Rather, the New Testament usage of the shame concept has definite and definable characteristics of its own. The purpose of this study is to isolate and give expression thereto

Where are the missing baryons in clusters?

Observations of clusters of galaxies suggest that they contain significantly fewer baryons (gas plus stars) than the cosmic baryon fraction. This `missing baryon' puzzle is especially surprising for the most massive clusters which are expected to be representative of the cosmic matter content of the universe (baryons and dark matter). Here we show that the baryons may not actually be missing from clusters, but rather are extended to larger radii than typically observed. The baryon deficiency is typically observed in the central regions of clusters (~0.5 the virial radius). However, the observed gas-density profile is significantly shallower than the mass-density profile, implying that the gas is more extended than the mass and that the gas fraction increases with radius. We use the observed density profiles of gas and mass in clusters to extrapolate the measured baryon fraction as a function of radius and as a function of cluster mass. We find that the baryon fraction reaches the cosmic value near the virial radius for all groups and clusters above 5e13 solar masses. This suggests that the baryons are not missing, they are simply located in cluster outskirts. Heating processes (shock-heating of the intracluster gas, plus supernovae and AGN feedback) that cause the gas to expand are likely explanations for these results. Upcoming observations should be able to detect these baryons.Comment: Submitted to PNA

The Amplitude of Mass Fluctuations

We determine the linear amplitude of mass fluctuations in the universe, sigma_8, from the abundance of massive clusters at redshifts z=0.5 to 0.8. The evolution of massive clusters depends exponentially on the amplitude of mass fluctuations and thus provides a powerful measure of this important cosmological parameter. The relatively high abundance of massive clusters observed at z>0.5, and the relatively slow evolution of their abundance with time, suggest a high amplitude of mass fluctuations: sigma_8=0.9 +-10% for Omega_m=0.4, increasing slightly to sigma_8=0.95 for Omega_m=0.25 and sigma_8=1.0 for Omega_m=0.1 (flat CDM models). We use the cluster abundance observed at z=0.5 to 0.8 to derive a normalization relation from the high-redshift clusters, which is only weakly dependent on Omega_m: sigma_8*Omega_m^0.14 = 0.78 +-0.08. When combined with recent constraints from the present-day cluster mass function (sigma_8*Omega_m^0.6=0.33 +-0.03) we find sigma_8=0.98 +-0.1 and Omega_m=0.17 +-0.05. Low sigma_8 values (<0.7) are unlikely; they produce an order of magnitude fewer massive clusters than observed.Comment: 12 pages including 3 figures; updated to match published versio

The Shape, Multiplicity, and Evolution of Superclusters in LambdaCDM Cosmology

We determine the shape, multiplicity, size, and radial structure of superclusters in the LambdaCDM concordance cosmology from z = 0 to z = 2. Superclusters are defined as clusters of clusters in our large-scale cosmological simulation. We find that superclusters are triaxial in shape; many have flattened since early times to become nearly two-dimensional structures at present, with a small fraction of filamentary systems. The size and multiplicity functions are presented at different redshifts. Supercluster sizes extend to scales of ~ 100 - 200 Mpc/h. The supercluster multiplicity (richness) increases linearly with supercluster size. The density profile in superclusters is approximately isothermal (~ R^{-2}) and steepens on larger scales. These results can be used as a new test of the current cosmology when compared with upcoming observations of large-scale surveys.Comment: 33 pages, 15 figures, accepted to ApJ; minor content changes, some figures removed to shorten pape

Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and hydrostatic equilibrium, with constraints from conservation of energy and pressure balance at the cluster boundary. The resulting properties of the gas for these simulated redshift zero clusters (the temperature distribution, mass-temperature and luminosity-temperature relations, and the gas fraction) are compared with observations in the X-ray of nearby clusters. The observed properties are reproduced only under the assumption that substantial energy injection from non-gravitational sources has occurred. Our model does not specify the source, but star formation and AGN may be capable of providing this energy, which amounts to 3 to 5 x10^{-5} of the rest mass in stars (assuming ten percent of the gas initially in the cluster forms stars). With the method described here it is possible to generate realistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-body simulations, with the distributions of internal halo properties (and their trends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure