G. J. Mathews

Observational constraints on accelerating brane cosmology with exchange between the bulk and brane

We explore observational constraints on a cosmological brane world scenario in which the bulk is not empty. Rather, exchange of mass energy between the bulk and the brane is allowed. The evolution of matter fields to an observer on the brane is then modified due to new terms in the energy-momentum tensor describing this exchange. We investigate the constraints from various cosmological observations on the flow of matter from the bulk into the brane. Interestingly, we show that it is possible to have a {lambda}=0 cosmology to an observer in the brane which satisfies standard cosmological constraints including the cosmic microwave background (CMB) temperature fluctuations, Type Ia supernovae at high redshift, and the matter power spectrum. This model even accounts for the observed suppression of the CMB power spectrum at low multipoles. In this cosmology, the observed cosmic acceleration is attributable to the flow of matter from the bulk to the brane. A peculiar aspect of this cosmology is that the present dark-matter content of the Universe may be significantly larger than that of a {lambda}CDM cosmology. Its influence, however, is offset by the dark-radiation term. Possible additional observational tests of this new cosmological paradigm are suggested.

Constraints on neutrino degeneracy from the cosmic microwave background and primordial nucleosynthesis

We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy based upon the latest high resolution CMB sky maps from BOOMERANG, DASI, and MAXIMA-1. We generate likelihood functions by marginalizing over

Chemical evolution of irregular galaxies and the primordial He-4 abundance

(\omegab h^2,\xinumt, \xinue, \Omega_\Lambda,h,n)

Exploring the neutrino mass hierarchy probability with meteoritic supernova material, ν -process nucleosynthesis, and θ 13 mixing

plus the calibaration uncertainties. We consider flat

Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field

\Omega_M + \Omega_\Lambda = 1

Detectability of cosmic dark flow in the type Ia supernova redshift-distance relation

cosmological models with two identical degenerate neutrino species,

Constraints on the birth of the universe and origin of cosmic dark flow

\xinumt \equiv \vert \xinum \vert = \vert \xinut \vert

Primordial nucleosynthesis: A cosmological point of view

and a small

Neutrino process with primitive meteorites and high power laser

\xinue

Realistic fission model and the r-process in neutron star mergers

. We assign weak top-hat priors on the electron-neutrino degeneracy parameter