We present analysis and modeling of X-ray spectra from the blast wave shock of DEM L71 in the Large Magellanic Cloud. This remnant exhibits widespread Balmer-dominated emission characteristic of nonradiative shocks in partially neutral gas. We have used both Chandra ACISS data and optical Fabry-Perot spectra of the blast wave to measure the electron and proton temperatures, respectively. In pri...

The standard afterglow model neglects the presence of the GRB prompt radiation ahead of the blast wave. In fact, the blast wave is dramatically influenced by the leading gamma-ray front which preaccelerates the ambient medium and loads it with electron-positron pairs. The front sweeps the medium outward with a high Lorentz factor and results in a spectacular effect: the GRB ejecta moves freely ...

There has been increasing evidence that at least some GRBs are emission beamed. The beamed GRB afterglow evolution has been discussed by several authors in the ultra-relativistic case. It has been shown that the dynamics of the blast wave will be significantly modified by the sideways expansion, and there may be a sharp break in the afterglow light curves under certain circumstances. However, t...

In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent e...

In this study, a sandwich beam with periodic multiple dissipative resonators in the sandwich core material is investigated for broadband wave mitigation and/or absorption. An analytical approach based on the transfer matrix method and Bloch theorem is developed for both infinite and finite sandwich structures. Wave attenuation constants are theoretically obtained to examine the effects of vario...

We show that the spectral shape of the low energy tails found for the time-integrated spectra of gamma-ray bursts, even in the absence of strong synchrotron cooling, can be significantly softer than the νFν ∝ ν4/3 asymptote predicted by synchrotron shock models. As we have noted in a previous work, blast wave deceleration via interaction with ambient material causes the characteristic electron ...

The time and angle dependent line and continuum emission from a dense torus around a cosmological gamma-ray burst source is simulated, taking into account photoionization, collisional ionization, recombination, and electron heating and cooling due to various processes. The importance of the hydrodynamical interaction between the torus and the expanding blast wave is stressed. Due to the rapid d...

We present observations of the young, oxygen-rich supernova remnant 1E 0102.2-7219 taken by the Chandra X-Ray Observatory during its orbital activation and checkout phase. The boundary of the blast-wave shock is clearly seen for the first time, allowing the diameter of the remnant and the mean blast-wave velocity to be determined accurately. The prominent X-ray bright ring of material may be th...

We treat the problem of adiabatic losses and stochastic particle acceleration in gamma-ray burst (GRB) blast waves that decelerate by sweeping up matter from an external medium. The shocked fluid is treated as a homogeneous expanding shell. The energy lost by nonthermal particles through adiabatic expansion is converted to the bulk kinetic energy of the outflow, permitting the evolution of the ...

Compressed-gas-driven shock tubes have become popular as a laboratory-scale replacement for field blast tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure thought to resemble a Friedlander wave, although this remains to be demonstrated theoretically. In this paper, we develop a semi-analytical model to predict the key characteristics of pseu...