A structure factor approach to the Sunyaev-Zel'dovich effect

Structure factor theory (SFT) is applied to analyze distortions to the Cosmic Microwave Background Radiation (CMBR) due the Sunyaev-Zel'dovich Effect (SZE) in typical clusters of galaxies. It is shown that a suitable structure factor associated to a collisionless (Knudsen) gas is able to reproduce the SZE distortion of the CMBR . Physical arguments suggest that SFT yields an approximate solution to the Kompaneets equation and sets plausible values for the two ``free'' parameters involved in the calculation of the spectral distortion. Finally, further applications of the SFT to other standard cosmological problems are briefly discussed.Comment: 6 pages, 3 figures. RevTex. Submitted to Physica

Complete constraints on a nonminimally coupled chaotic inflationary scenario from the cosmic microwave background

We present complete constraints imposed from observations of the cosmic microwave background radiation (CMBR) on the chaotic inflationary scenario with a nonminimally coupled inflaton field proposed by Fakir and Unruh (FU). Our constraints are complete in the sense that we investigate both the scalar density perturbation and the tensor gravitational wave in the Jordan frame, as well as in the Einstein frame. This makes the constraints extremely strong without any ambiguities due to the choice of frames. We find that the FU scenario generates tiny tensor contributions to the CMBR relative to chaotic models in minimal coupling theory, in spite of its spectral index of scalar perturbation being slightly tilted. This means that the FU scenario will be excluded if any tensor contributions to CMBR are detected by the forthcoming satellite missions. Conversely, if no tensor nature is detected despite the tilted spectrum, a minimal chaotic scenario will be hard to explain and the FU scenario will be supported.Comment: 7 pages, no figure, RevTeX, to appear in Phys.Rev. D59 (Mar. 15, 1999

Working Group Report: Neutrino and Astroparticle Physics

This is the report of neutrino and astroparticle physics working group at WHEPP-8. We present the discussions carried out during the workshop on selected topics in the above fields and also indicate progress made subsequently. The neutrino physics subgroup studied the possibilites of constraining neutrino masses, mixing and CPT violation in lepton sector from future experiments. Neutrino mass models in the context of abelian horizontal symmetries, warped extra dimensions and in presence of triplet Higgs were studied. Effect of threshold corrections on radiative magnification of mixing angles was investigated. The astroparticle physics subgroup focused on how various particle physics inputs affect the CMBR fluctuation spectrum, and on brane cosmology. This report also contains an introduction on how to use the publicly available code CMBFAST to calculate the CMBR fluctuations.Comment: Prepared for the 8th Workshop on High-Energy Physics Phenomenology (WHEPP-8), IIT Mumbai, India, 5-16 Jan 200

Active-Sterile neutrino oscillations and BBN+CMBR constraints

We show how active-sterile neutrino oscillations in the early Universe can play an interesting role in explaining the current observations of CMBR anisotropies and light element abundances. We describe different possible phenomenological scenarios in the interpretation of present data and how active-sterile neutrino oscillations can provide a viable theoretical framework.Comment: Some changes, to appear in Phys. Rev.