[en] Within an astrophysical context corresponding to high densities, a self-gravitating model is studied, which is the set of an extreme material medium of infinite conductivity and of a magnetic field. Corresponding shock waves generate necessarily, in general, gravitational shock waves

[en] Many extragalactic radio sources contain jets of plasma moving away from a central source at relativistic velocities. The stability of the jets is remarkable, as they can travel for hundreds or thousands of jet diameters without breaking up. A two-dimensional, cylindrically symmetric, relativistic hydrodynamics model was created to address the issue of jet stability. A complete description of the model is presented here. The description begins with the derivation of the relativistic fluid dynamics equations, in both conservative and characteristic forms, with specialization to the two dimensional, cylindrical problem. The grid and metric specification, the finite differencing, the time integration method, and linear stability theory are discussed in detail. The general problem of boundary condition specification for hyperbolic systems of differential equations, in a space-time with any number of spatial coordinates, is also analyzed. Boundary conditions for the relativistic fluid dynamics equations are given for the cylindrical case. Comparison of numerical and analytical solutions to test problems (including a relativistic shock tube problem) reveals that the numerical scheme represents shocks and smooth solutions properly, but allows excess diffusion at contact discontinuities

No abstract available

[en] In the light of recent results relating dynamic and thermodynamic stability of relativistic stars and black holes, we re-examine the relationship between ‘turning points’—i.e., extrema of thermodynamic variables along a 1-parameter family of solutions—and instabilities. We give a proof of Sorkin’s general result—showing the existence of a thermodynamic instability on one side of a turning point—that does not rely on heuristic arguments involving infinite-dimensional manifold structure. We use the turning point results to prove the existence of a dynamic instability of black rings in five spacetime dimensions in the region where c_J > 0, in agreement with a result of Figueras, Murata and Reall. Communicated by H Reall (paper)

[en] Nuclear structure studies for even–even nuclei in the mass region $\backsim <!--\; ???\; -->130$, have been performed, with a special focus around N or Z = 64. On the onset of deformation and lying between two closed shell, these nuclei have attracted attention in a number of studies. A revisit to these experimentally accessible nuclei has been made via the relativistic mean field. The role of pairing and density depletion in the interior has been specially investigated. Qualitative analysis between two versions of relativistic mean field suggests that there is no significant difference between the two approaches. Moreover, the role of the filling ${\mathrm{s}}_{1/2}$ orbital in density depletion towards the centre has been found to be consistent with our earlier work on the subject Shukla and Åberg (2014 Phys. Rev. C 89 014329). (paper)

[en] We generalize the derivation of electromagnetic fields of a charged particle moving with a constant acceleration Singal (2011 Am. J. Phys. 79 1036) to a variable acceleration (piecewise constants) over a small finite time interval using Coulomb's law, relativistic transformations of electromagnetic fields and Thomson's construction Thomson (1904 Electricity and Matter (New York: Charles Scribners) ch 3). We derive the average Lorentz self-force for a charged particle in arbitrary non-relativistic motion via averaging the fields at retarded time. (paper)

[en] Published in summary form only

[en] We identify the reflected component in the GINGA spectra of Nova Muscae, a Black Hole transient system which has been used as the prototype for the recent advection dominated disk models. We see that the reflected spectrum is generally significantly relativistically smeared, and use this and the amount of reflection to track the innermost extent of the accretion disk. We see that the optically thick disk does retreat during the decline, but more slowly than predicted by the advective models, posing problems for this description of the accretion flow

[en] In this paper, we analyse a number of paradoxical teaching problems of classical electrodynamics, dealing with the relativistic transformation of force for complex macro systems, consisting of a number of subsystems with nonzero relative velocities such as electric circuits that change their shape in the course of time

[en] Visualizations that adopt a first-person point of view allow observation and, in the case of interactive simulations, experimentation with relativistic scenes. This paper gives examples of three types of first-person visualizations: watching objects that move at nearly the speed of light, being a high-speed observer looking at a static environment and having a look-around near a compact object. I illustrate and explain the main aspects of the visual observations, outline their use in teaching relativity and report on teaching experiences. For teaching purposes, our visualization work is available on the website www.spacetimetravel.org and its German counterpart www.tempolimit-lichtgeschwindigkeit.de. This paper assumes some basic knowledge about relativity on the part of the reader. It addresses instructors of physics at the undergraduate and advanced secondary school level as well as their students