The properties of uniformly rotating white dwarfs (RWDs) are analyzed within the framework of general relativity. Hartle's formalism is applied to construct the internal and external solutions to the Einstein equations. The WD matter is described by the relativistic Feynman-Metropolis-Teller equation of state which generalizes the Salpeter's one by taking into account the finite size of the nuclei, the Coulomb interactions as well as electroweak equilibrium in a self-consistent relativistic fashion. The mass M, radius R, angular momentum J, eccentricity ǫ, and quadrupole moment Q of RWDs are calculated as a function of the central density ρ c and rotation angular velocity Ω. We construct the region of stability of RWDs (J-M plane) taking into account the mass-shedding limit, inverse β-decay instability, and the boundary established by the turning-points of constant J sequences which separates stable from secularly unstable configurations. We found the minimum rotation periods ∼ 0.3, 0.5, 0.7 and 2.2 seconds and maximum masses ∼ 1.500, 1.474, 1.467, 1.202 M ⊙ for 4 He, 12 C, 16 O, and 56 Fe WDs respectively. By using the turning-point method we found that RWDs can indeed be axisymmetrically unstable and we give the range of WD parameters where it occurs. We also construct constant rest-mass evolution tracks of RWDs at fixed chemical composition and show that, by loosing angular momentum, sub-Chandrasekhar RWDs (mass smaller than maximum static one) can experience both spin-up and spin-down epochs depending on their initial mass and rotation period while, super-Chandrasekhar RWDs (mass larger than maximum static one), only spin-up.

Two popular models of optically thick relativistic outflows exist: the wind and the shell. We propose a unified treatment of photospheric emission within these models. We show that quite counterintuitive situations may appear when e.g. geometrically thin shell may behave as thick wind. For this reason we introduce notions of photon thick and photon thin outflows. They appear more general and better physically motivated than winds and shells when photospheric emission is considered.We obtain light curves and observed spectra for both photon thick and photon thin outflows. In the photon thick case we generalize the results obtained for steady wind. It is our main finding that the photospheric emission from the photon thin outflow is dominated by diffusion and produces non thermal time integrated spectra, which may be described by the Band function well known in the GRB literature.Energetic GRBs should produce photon thin outflows and therefore when only time integrated spectra for such GRBs are available we naturally expect them to have a Band shape. In the literature Band spectra for the photospheric emission of GRBs are obtained only involving additional dissipative mechanisms which are not required here.

We studied the decoupling of photons from ultra-relativistic spherically symmetric outflows expanding with constant velocity by means of Monte-Carlo (MC) simulation. For outflows with finite width we confirm the existence of two regimes: photon thick and photon thin introduced recently by Ruffini, Siutsou, Vereshchagin (2011), hereafter RSV. The probability density function of photon last scattering is shown to be very different in these two cases. We also obtained spectra as well as light curves. In photon thick case, the time integrated spectrum is much broader than the Planck function and its shape is well described by the fuzzy photosphere approximation introduced by RSV. In the photon thin case we confirm the crucial role of photon diffusion, hence the probability density of decoupling has a maximum near the diffusion radius, well below the photosphere. Its spectrum has Band shape. It is produced when the outflow is optically thick and its peak is formed at diffusion radius. Subject headings: Gamma Ray: bursts -methods: numerical -radiation mechanisms: thermal R D = τ 0 Γ 2 R 0 l 2 1/3 .

On the basis of a fermionic dark matter model we fit rotation curves of The HI Nearby Galaxy Survey THINGS sample and compare our 3-parametric model to other models widely used in the literature: 2-parametric Navarro-Frenk-White, pseudoisothermal sphere, Burkhert models, and 3-parametric Einasto model, suggested as the new "standard dark matter profile" model in the paper by Chemin et. al., AJ 142 (2011) 109. The results from the fitting procedure provides evidence for an underlying fermionic nature of the dark matter candidate, with rest mass above the keV regime.