November 1994 arXiv papers — page 12

Wayne Hu, Naoshi Sugiyama

Working toward a model independent understanding of cosmic microwave background (CMB) anisotropies and their significance, we undertake a comprehensive and self-contained study of scalar perturbation theory. Initial conditions, evolution, thermal history, matter content, background dynamics, and geometry all play a role in determining the anisotropy. By empl

Hyron Spinrad, Arjun Dey, James R. Graham

We report on Keck observations and confirm the redshift of the most distant galaxy known: 8C1435+63 at z=4.25. The spectrum shows a strong Ly$α$ line, a Ly$α$ forest continuum break and a continuum break at $λ_{rest}=912$Å. The Ly$α$ emission is spatially extended and roughly aligned with the radio source. The galaxy shows a double structure in the $I$-band

Arjun Dey, Hyron Spinrad, Mark Dickinson

We report the discovery of a z=2.76 radio galaxy, MG1019+0535, with an unusual spectrum. Ly$α$, which usually dominates the spectra of high redshift radio galaxies, is very weak and the strongest lines in the spectrum are CIV$λ$1549 and HeII$λ$1640. We speculate that dust is responsible for attenuating the Ly$α$ line. This object provides more evidence for d

Nick Kaiser, Gordon Squires, Tom Broadhurst

We develop and test a method for measuring the gravitational lensing induced distortion of faint background galaxies. We first describe how we locate the galaxies and measure a 2-component `polarisation' or ellipticity statistic $e_α$ whose expectation value should be proportional to the gravitational shear $γ_α$. We then show that an anisotropic instrum

B. Paczynski, K. Z. Stanek, A. Udalski, M. Szymanski

The analysis of the first three years of the OGLE data revealed 12 microlensing events of the Galactic bulge stars, with the characteristic time scales in the range $ 8.6 < t_0 < 80 $ days, where $ t_0 = R_E / V $. A complete sample of nine events gave the optical depth to gravitational microlensing larger than $(3.3 \pm 1.2) \times 10^{-6}$, in excess of cu

by F. X. Timmes, S. E. Woosley, Thomas A. Weaver

Using the output from a grid of 60 Type II supernova models (Woosley \& Weaver 1994) of varying mass (11 $\ltaprx$ M/M\sun $\ltaprx$ 40) and metallicity (0, 10$^{-4}$, 0.01, 0.1, and 1 Z\sol), the chemical evolution of 76 stable isotopes, from hydrogen to zinc, is calculated. The chemical evolution calculation employs a simple dynamical model for the Galaxy

A. M. Dunn, Raymond Laflamme

Peebles has suggested an interesting method to trace back in time positions of galaxies called the least action method. This method applied on the Local Group galaxies seems to indicate that we live in an $Ω\approx 0.1$ Universe. We have studied a CDM N-body simulation with $Ω=0.2$ and $H=50 kms^{-1}/Mpc$ and compare trajectories traced back from the Least A

Philippe P. Brieu, FJ Summers, Jeremiah P. Ostriker

An adaptation of the Particle-Particle/Particle-Mesh (P3M) code to the special purpose hardware GRAPE is presented. The short range force is calculated by a four chip GRAPE-3A board, while the rest of the calculation is performed on a Sun Sparc 10/51 workstation. The limited precision of the GRAPE hardware and algorithm constraints introduce stochastic error

Salman Habib, Robert D. Ryne

A recently developed method for the calculation of Lyapunov exponents of dynamical systems is described. The method is applicable whenever the linearized dynamics is Hamiltonian. By utilizing the exponential representation of symplectic matrices, this approach avoids the renormalization and reorthogonalization procedures necessary in usual techniques. It is