Related papers: A Photon Splitting Cascade Model of Soft Gamma-Ray…
We examine an external trigger mechanism that gives rise to the intense soft gamma-ray repeater (SGR) giant flares. Out of the three giant flares, two showcased the existence of a precursor, which we show to have had initiated the main…
We present the results of an analysis of the quiescent X-ray emission from the Soft Gamma-Ray Repeater SGR1806-20, taken during an INTEGRAL ultra-deep survey of the Galactic Center region in autumn 2003. The total effective exposure time…
The energy source powering the X-ray emission from anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) is still uncertain. In one scenario, the presence of an ultramagnetized neutron star, or ``magnetar'', with B on the order…
Among the variety of correlated states exhibited by twisted bilayer graphene, cascades in the spectroscopic properties and in the electronic compressibility occur over larger ranges of energy, twist angle and temperature compared to other…
The role of a photospheric component and of pair breakdown is examined in the internal shock model of gamma-ray bursts. We discuss some of the mechanisms by which they would produce anomalously steep low energy slopes, X-ray excesses and…
Building on a general relativistic magnetohydrodynamic simulation of a short gamma-ray burst (sGRB) jet with initial magnetization $\sigma_0=150$, propagating through the dynamical ejecta from a binary neutron star merger, we identify…
Sub-photospheric shock dissipation is one of the main proposed mechanisms for producing the prompt gamma-ray burst (GRB) emission. Such shocks are mediated by scattering of radiation. We introduce a time dependent, special relativistic code…
Gamma-Ray Burst (GRB) afterglows are well described by synchrotron emission from relativistic blast waves expanding into an external medium. The blast wave is believed to amplify the magnetic field and accelerate the electrons into a power…
Synchrotron emission is believed to be a major radiation mechanism during gamma-ray bursts' (GRBs) prompt emission phase. A significant drawback of this assumption is that the theoretical predicted spectrum, calculated within the framework…
It was suggested that some of the short-duration Gamma-Ray Bursts (GRB) are giant flares of Soft Gamma-ray Repeaters (SGR) in nearby galaxies. To test this hypothesis, I have constructed a sample of 47 short GRBs, detected by the…
A leading mechanism for producing cosmological gamma-ray bursts (GRBs) is via ultra-relativistic particles in an expanding fireball. The kinetic energy of the particles is converted into thermal energy in a forward shock and a reverse…
We present a systematic analysis of all archival Chandra observations of the soft-gamma repeater SGR 0526-66. Our results show that the X-ray flux of SGR 0526-66 decayed by about 20% between 2000 and 2009. We employ physically motivated…
We present Monte Carlo simulations of radiative transfer in magnetar atmospheres. We include the effects of vacuum polarization, electron and proton scattering, and free-free absorption. Simulations are performed for the atmosphere model…
We present the results of the GRANAT/SIGMA hard X-/soft gamma-ray long-term monitoring of the Galactic Center (GC) region concerning the source GRO J1744-28, discovered on 1995 Dec. 2 by CGRO/BATSE. SIGMA observed the region containing the…
Non-thermal quiescent X-ray emission extending between 10 keV and around 150 keV has been seen in about 10 magnetars by RXTE, INTEGRAL, Suzaku, NuSTAR and Fermi-GBM. For inner magnetospheric models of such hard X-ray signals, inverse…
Radio waves undergo scattering by small-scale density fluctuations during propagation through the solar-terrestrial environment, substantially affecting the observed characteristics of solar radio bursts. This scattering process can be…
We discuss observations of the quiescent emission from the soft gamma repeater SGR 1806-20 by the Rossi X-ray Timing Explorer. We find that the 2-20 keV RXTE data is consistent with a constant spectral shape during both active bursting…
We study the light scattered from randomly rough, one-dimensional self-affine fractal silver surfaces with nanoscale lower cutoff, illuminated by s- or p-polarized Gaussian beams a few microns wide. By means of rigorous numerical…
The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst…
Radiation-mediated shocks (RMSs) occurring below the photosphere in a gamma-ray burst (GRB) jet could play a crucial role in shaping the prompt emission. In this paper, we study the time-resolved signal expected from such early shocks. We…