ﻻ يوجد ملخص باللغة العربية
Few years ago, Boltzmann neutrino transport led to a new and reliable generation of spherically symmetric models of stellar core collapse and postbounce evolution. After the failure to prove the principles of the supernova explosion mechanism, these sophisticated models continue to illuminate the close interaction between high-density matter under extreme conditions and the transport of leptons and energy in general relativistically curved space-time. We emphasize that very different input physics is likely to be relevant for the different evolutionary phases, e.g. nuclear structure for weak rates in collapse, the equation of state of bulk nuclear matter during bounce, multidimensional plasma dynamics in the postbounce evolution, and neutrino cross sections in the explosive nucleosynthesis. We illustrate the complexity of the dynamics using preliminary 3D MHD high-resolution simulations based on parameterized deleptonization. With established spherically symmetric models we show that typical features of the different phases are reflected in the predicted neutrino signal and that a consistent neutrino flux leads to electron fractions larger than 0.5 in neutrino-driven supernova ejecta.
We investigate spherically symmetric cosmological models in Einstein-aether theory with a tilted (non-comoving) perfect fluid source. We use a 1+3 frame formalism and adopt the comoving aether gauge to derive the evolution equations, which form a wel
We give a general description of the construction of weighted spherically symmetric metrics on vector bundle manifolds, i.e. the total space of a vector bundle $Erightarrow M$, over a Riemannian manifold $M$, when $E$ is endowed with a metric connect
We use the 1+3 frame formalism to write down the evolution equations for spherically symmetric models as a well-posed system of first order PDEs in two variables, suitable for numerical and qualitative analysis.
Hermann Bondis 1952 paper On spherically symmetrical accretion is recognized as one of the foundations of accretion theory. Although Bondi later remarked that it was not much more than an examination exercise, his mathematical analysis of spherical a
In the macroscopic gravity approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically