Related papers: Hydrodynamic Time Scales and Temporal Structure in…
We present a mathematical framework to produce a numerical estimation to the distribution of the lifetime of bubbles emerging from first order cosmological phase transitions. In a precedent work, we have implemented the Sound Shell model to…
Freeze-out of particles in relativistic hydrodynamics is considered across a 3-dimensional space-time hypersurface. The conservation laws for time-like parts of the freeze-out hypersurface require different values of temperature, baryonic…
Density fluctuations produced by supersonic turbulence are of great importance to astrophysical chemical models. A property of these density fluctuations is that the two point correlation function decreases with increasing scale separation.…
When two plasmas collide, their interaction can be mediated by collisionless plasma instabilities or binary collisions between particles of each shell. By comparing the maximum growth rate of the collisionless instabilities with the…
I review recent results derived from numerical simulations of the turbulent interstellar medium (ISM), in particular concerning the nature and formation of turbulent clouds, methods for comparing the structure in simulations and…
We solve numerically the equations of motion for the collapse of a shell of baryonic matter, made of galaxies and substructure of $ 10^{6} M_{\odot} \div 10^{9} M_{\odot}$, taking into account the dynamical friction and the parameters on…
We use a new method of analysis to determine parameters of cosmological gamma-ray bursts (GRBs), assuming that their distribution follows the star-formation history of the universe. Spectral evolution is calculated from an external shock…
Based on the study of temporal asymmetry of 631 gamma ray bursts from the BATSE 3B catalog by Link and Epstein [Ap J 466, 764 (1996)], we identify the population of bursts whose rising times are longer than their decays, thus showing…
We investigate the connection between the inertial range and the dissipation range statistics of rotating turbulence through detailed simulations of a helical shell model and a multifractal analysis. In particular, by using the latter, we…
We examine the hydrodynamics of a granular gas using numerical simulation. We demonstrate the appearance of shearing and clustering instabilities predicted by linear stability analysis, and show that their appearance is directly related to…
In three-dimensional turbulent flows, the flux of energy from large to small scales breaks time symmetry. We show here that this irreversibility can be quantified by following the relative motion of several Lagrangian tracers. We find by…
We study a cosmological scenario for gamma ray bursts (GRBs) where relativistic flows interact with dense radiation fields. It is shown that this scenario is plausible in very dense stellar regions which are known to exist in collapsed…
The turbulent dynamics of nearby and extragalactic gas structures can be studied with the column density power spectrum, which is often described by a broken power-law.In an extragalactic context, the breaks in the power spectra have been…
A turbulent flow is maintained by an external supply of kinetic energy, which is eventually dissipated into heat at steep velocity gradients. The scale at which energy is supplied greatly differs from the scale at which energy is…
We examine analytically and numerically the evolution of a relativistic fireball. We show that, after an early rearrangement phase, most of the matter and energy in the fireball is concentrated within a narrow shell. The shell propagates at…
A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. There are two shocks…
It has been widely accepted that relativistic effects have to be used for modelling the wide classes of events associated with active galactic nuclei and galactic superluminal sources. Here we propose a simple analytical model of…
Two tests for cosmological time dilation in $\gamma$-ray bursts -- the peak alignment and auto-correlation statistics -- involve averaging information near the times of peak intensity. Both tests require width corrections, assuming…
The spatial power spectrum of the HI 21 cm intensity in the Small Magellanic Cloud (Stanimirovic et al 1999) is a power law over scales as large as those of the SMC itself. It was interpreted as due to turbulence by Goldman (2000) and by…
The equations of relativistic hydrodynamics are transformed so that steps forward in time preserves local simultaneity. In these variables, the space-time coordinates of neighboring points on the mesh are simultaneous according to co-moving…