Majorana neutrino oscillations in vacuum

In the context of a type I seesaw scenario which leads to get light left-handed and heavy right-handed Majorana neutrinos, we obtain expressions for the transition probability densities between two flavor neutrinos in the cases of left-handed and right-handed neutrinos. We obtain these expressions in the context of an approach developed in the canonical formalism of Quantum Field Theory for neutrinos which are considered as superpositions of mass-eigenstate plane waves with specific momenta. The expressions obtained for the left-handed neutrino case after the ultra-relativistic limit is taking lead to the standard probability densities which describe light neutrino oscillations. For the right-handed neutrino case, the expressions describing heavy neutrino oscillations in the non-relativistic limit are different respect to the ones of the standard neutrino oscillations. However, the right-handed neutrino oscillations are phenomenologically restricted as is shown when the propagation of heavy neutrinos is considered as superpositions of mass-eigenstate wave packets.Comment: 25 pages, abstract changed, two sections added, some references adde

Preparation to the CMB PLANCK data analysis, estimation of the contamination due to the galactic polarized emissions

This work is point of the preparation to the analysis of the PLANCK satellite data. The PLANCK satellite is an ESA mission which has been launched the 14th of may 2009 and is dedicaced to the measurement of the Cosmic Microwave Background (CMB) in temperature and polarization. The presence of diffuse Galactic polarized emissions disturb the measurement of the CMB anisotropies, in particular in polarization. Therefore a precise knowledge of these emissions is needed to obtain the level of accuracy required for PLANCK. In this context, we have developed and implemented a coherent 3D model of the two mains polarized Galactic emissions : synchrotron and thermal dust. We have compared these models to preexisting data: the 23 GHz band of the WMAP data, the 353 GHz Archeops data and the 408 MHz all-sky continuum survey. We extrapolate these models to the frequencies where the CMB dominates and we are able to estimate the contribution of polarized foreground emissions to the polarized CMB emission measured with PLANCK.Comment: Proceeding of the International Workshop on Cosmic Structure and Evolution - Cosmology2009, September 23-25, 2009 Bielefeld, German

Cylindrical radiator analysis with interior insulated

Size and weight evaluation of insulated cylindrical radiators used in SNAP-8 heat rejection syste

Anisotropic thermal emission from magnetized neutron stars

The thermal emission from isolated neutron stars is not well understood. The X-ray spectrum is very close to a blackbody but there is a systematic optical excess flux with respect to the extrapolation to low energy of the best blackbody fit. This fact, in combination with the observed pulsations in the X-ray flux, can be explained by anisotropies in the surface temperature distribution.We study the thermal emission from neutron stars with strong magnetic fields in order to explain the origin of the anisotropy. We find (numerically) stationary solutions in axial symmetry of the heat transportequations in the neutron star crust and the condensed envelope. The anisotropy in the conductivity tensor is included consistently. The presence of magnetic fields of the expected strength leads to anisotropy in the surface temperature. Models with toroidal components similar to or larger than the poloidal field reproduce qualitatively the observed spectral properties and variability of isolated neutron stars. Our models also predict spectral features at energies between 0.2 and 0.6 keV.Comment: 18 pages, 19 figures, version accepted for publication in A&