We investigate the cosmological Fisher information in the non-linear dark-matter power spectrum in the context of the halo model. We find that there is a plateau in information content on translinear scales which is generic to all cosmological parameters we tried. There is a rise in information on smaller scales, but we find that it is quite degenerate among different cosmological parameters (e...

Neutrinos can play an important role in the evolution of the Universe, modifying some of the cosmological observables. We describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass. Cosmology can provide information on the absolute scale of neutrino masses, complementary to the results of tritium beta decay and neutrinoless d...

We present explicit expressions for the calculation of cosmological look back time, for zero cosmological constant and arbitrary density parameter Ω, which, in the limit as redshift becomes infinite, give the age of the universe. The case for non-zero cosmological constant is most easily solved via numerical integration. The most distant objects presently known (approaching redshift z = 5) have...

In popular cosmological scenarios, some time beyond a redshift of 10, stars within protogalaxies created the first heavy elements; these systems, together perhaps with an early population of quasars, generated the ultraviolet radiation and mechanical energy that reheated and reionized the cosmos. The history of the Universe during and soon after these crucial formative stages is recorded in the...

In this thesis we focus on studying the physics of cosmological recombination and how the details of recombination affect the Cosmic Microwave Background (CMB) anisotropies. We present a detailed calculation of the spectral line distortions on the CMB spectrum arising from the Lyα and two-photon transitions in the recombination of hydrogen (H), as well as the corresponding lines from helium (He...

The cosmological parameters that I will emphasize are the Hubble parameter H0 ≡ 100h km s −1 Mpc, the age of the universe t0, the average matter density Ωm, the baryonic matter density Ωb, the neutrino density Ων , and the cosmological constant ΩΛ. The evidence currently favors t0 ≈ 13 Gyr, h ≈ 0.65, Ωm ≈ 0.4 ± 0.1, Ωb = 0.02h , 0.001 < Ων < 0.1, and ΩΛ ≈ 0.7.

An overview is provided of the singularity theorems in cosmological contexts at a level suitable for advanced graduate students. The necessary background from tensor and causal geometry to understand the theorems is supplied, the mathematical notion of a cosmology is described in some detail and issues related to the range of validity of general relativity are also discussed. ∗To be published i...

The magnitude-redshift relation is one of the tools for a direct observational approach to cosmology. The discovery of high redshift Type Ia supernovae (SNIa) and their use as " standard candles " has resurrected interest in this approach. Recently collected data have been used to address the problem of measuring the cosmologi-cal parameters of the universe. Analysed in the framework of homogen...

We prove that a class of one-loop partition functions found by Dienes, giving rise to a vanishing cosmological constant to one-loop, cannot be realized by a consistent lattice string. The construction of non-supersymmetric string with a vanishing cosmological constant therefore remains as elusive as ever. We also discuss a new test that any one-loop partition function for a lattice string must ...