The 2dF Galaxy Redshift Survey as a Cosmological Laboratory

The 2dF Galaxy Redshift Survey (2dFGRS) of 230,000 redshifts of nearby (z~0.1) galaxies is now complete. It has allowed the 2dFGRS team and others to estimate fundamental cosmological parameters and to study galaxy intrinsic properties. Here we highlight three recent key results from the survey: (i) an upper limit of about 2eV on the total mass of the three neutrino flavours, and an intriguing reasonable fitting of the 2dFGRS power spectrum to a Mixed Dark Matter model without a Cosmological Constant, but with a low Hubble constant; (ii) the bimodality of the galaxy population in both spectral parameterisation and in colour; and (iii) the clustering of different galaxy types and evidence for relative stochastic biasing.Comment: Based on invited talks at RESCEU6 (Tokyo) and 'Tully60' (Sydney); to appear in Pub. Ast. Soc. of Australia, ed. J. Bland-Hawthorn; 4 pages, 4 figure

Phenomenological construction of a relativistic nucleon-nucleon interaction for the superfluid gap equation in finite density systems

We construct phenomenologically a relativistic particle-particle channel interaction which suits the gap equation for nuclear matter. This is done by introducing a density-independent momentum-cutoff parameter to the relativistic mean field (Hartree and Hartree-Fock) models so as to reproduce the pairing properties obtained by the Bonn-B potential and not to change the saturation property. The interaction so obtained can be used for the Relativistic Hartree-Bogoliubov calculation, but some reservation is necessary for the Relativistic Hartree-Fock-Bogoliubov calculation.Comment: 30 pages, 18 eps figures, uses elsart. Major revision --- Hartree-Fock calculations are added. To appear in Nuclear Physics

Superfluid vortices in neutron stars

A microscopic, quantum mechanical model for neutron vortices in the crust of a neutron star is presented. After a brief introduction to the Bogoliubov- de Gennes equations, which form the basis for our calculations, we present results for density distributions, vortex core sizes and vortex energies, both for an isolated neutron vortex and for the case when the vortex core overlaps with a cylindrical nucleus. Earlier results on the vortex core size are confirmed, indicating a much less dramatic variation of the vortex core size with density than predicted by the BCS formula.Comment: 28 pages, 8 figures. To appear in Astronomy & Astrophysic

Detection of transplanckian effects in the cosmic microwave background

Quantum gravity effects are expected to modify the primordial density fluctuations produced during inflation and leave their imprint on the cosmic microwave background observed today. We present a new analysis discussing whether these effects are detectable, considering both currently available data and simulated results from an optimal CMB experiment. We find that the WMAP (Wilkinson Microwave Anisotropy Probe) data show no evidence for the particular signature considered in this work but give an upper bound on the parameters of the model. However, a hypothetical experiment shows that with proper data, the trans-Planckian effects should be detectable through alternate sampling methods. This fuzzy conclusion is a result of the nature of the oscillations, since they give rise to a likelihood hypersurface riddled with local maxima. A simple Bayesian analysis shows no significant evidence for the simulated data to prefer a trans-Planckian model. Conventional Markov chain Monte Carlo (MCMC) methods are not suitable for exploring this complicated landscape, but alternative methods are required to solve the problem. This, however, requires extremely high-precision data.Comment: 9 pages, 22 figure

Are all perturbations created equal? An analysis of the WMAP 5- and 7-year data without inflationary prejudice

We submit recent claims of a semi-significant detection of primordial tensor perturbations in the WMAP data to a closer scrutiny. Our conclusion is in brief that no such mode is present at a detectable level once the analysis is done more carefully. These claims have their root in a brief debate in the late 1990s about the standard calculation of the scalar and tensor spectra in standard inflationary theory, where Grishchuk and collaborators claimed that their amplitudes should be roughly equal. We give a brief summary of the debate and our own reasons for why the standard calculation is correct.Comment: 12 pages, submitted to Phys. Rev.

Triplet Pairing in Neutron Matter

The separation method developed earlier by us [Nucl. Phys. {\bf A598} 390 (1996)] to calculate and analyze solutions of the BCS gap equation for $^1$S$_0$ pairing is extended and applied to $^3$P$_2$--$^3$F$_2$ pairing in pure neutron matter. The pairing matrix elements are written as a separable part plus a remainder that vanishes when either momentum variable is on the Fermi surface. This decomposition effects a separation of the problem of determining the dependence of the gap components in a spin-angle representation on the magnitude of the momentum (described by a set of functions independent of magnetic quantum number) from the problem of determining the dependence of the gap on angle or magnetic projection. The former problem is solved through a set of nonsingular, quasilinear integral equations, providing inputs for solution of the latter problem through a coupled system of algebraic equations for a set of numerical coefficients. An incisive criterion is given for finding the upper critical density for closure of the triplet gap. The separation method and its development for triplet pairing exploit the existence of a small parameter, given by a gap-amplitude measure divided by the Fermi energy. The revised BCS equations admit analysis revealing universal properties of the full set of solutions for $^3$P$_2$ pairing in the absence of tensor coupling, referring especially to the energy degeneracy and energetic order of these solutions. The angle-average approximation introduced by Baldo et al. is illuminated in terms of the separation-transformed BCS problem and the small parameter expansion..