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Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor (GBM) find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emission component, but also includes a statistically highly significant thermal spectral contribution [14]. The simultaneous observation of the thermal and non-thermal components allows us to confidently identify the two emission components. The fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non-thermal emission occurs at larger radii. Our results imply either a very high efficiency for the non-thermal process, or a very small size of the region at the base of the flow, both quite challenging for the standard fireball model. These problems are resolved if the jet is initially highly magnetized and has a substantial Poynting flux. [ABSTRACT FROM AUTHOR]

We suggest that non-thermal emission can be produced by multiple scatterings of the photons between the supernova ejecta and pre-shock material in supernova shock breakout. Such bulk-Comptonization process may significantly change the original thermal photon spectrum, forming a power-law non-thermal component at higher energies. We then show that the luminous X-ray outburst XRO081009 associated with SN2008D is likely to be such shock breakout emission from an ordinary type Ib/c supernova. [ABSTRACT FROM AUTHOR]

The rapid follow-up of gamma-ray burst (GRB) afterglows made possible by the multi-wavelength satellite Swift, launched in November 2004, has put under a microscope the GRB early post-burst behavior, This is leading to a significant reappraisal and expansion of the standard view of the GRB early afterglow behavior, and its connection to the prompt gamma-ray emission. In addition to opening up the previously poorly known behavior on minutes to hours timescales, two other new pieces in the GRB puzzle being filled in are the the discovery and follow-up of short GRB afterglows, and the opening up of the z >= 6 redshift range. We review some of the current theoretical interpretations of these new phenomena. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Observations of gamma ray bursts (GRBs) with Swift produced the initially surprising result that many bursts have large X-ray flares superimposed on the underlying afterglow. These flares were sometimes intense, rapid, and late relative to the nominal prompt phase. The most intense of these flares was observed by XRT with a flux > 500× the afterglow. This burst then surprised observers by flaring again after > 10000 s. The intense flare can be most easily understood within the context of the standard fireball model, if the internal engine that powers the prompt GRB emission is still active at late times. Recent observations indicate that X-ray flares are detected in ∼1/3 of XRT detected afterglows. By studying the properties of the varieties of flares (such as rise/fall time, onset time, spectral variability, etc.) and relating them to overall burst properties, models of flare production and the GRB internal engine can be constrained. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Most current knowledge about GRBs is based on sub-MeV electromagnetic signals. However, some observations and recent theoretical work indicate that important clues may be gleaned from their GeV-TeV photon spectra. In addition, one expects GRB to be prominent in two other potentially important non-electromagnetic channels, gravitational waves and TeV or higher energy neutrinos. The former is a natural consequence of compact merger or collapse scenarios, while the latter is associated with a hadronic component in the outflow. The information in these channels and prospects for their detection are discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Detectability of high redshift GRB afterglows are carefully discussed. Using standard assumptions, we find that Chandra, XMM and Swift XRT can potentially detect GRBs in the X-ray band out to very high redshifts z>= 30. In the K and M bands, the JWST and ground-based telescopes are potentially able to detect GRBs even one day after the trigger out to z ∼ 16 and 33. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Significant gravitational wave emission is expected from gamma-ray bursts arising from compact stellar mergers, and possibly also from bursts associated with fast-rotating massive stellar core collapses. These models have in common a high angular rotation rate, and observations provide evidence for jet collimation of the photon emission, with properties depending on the polar angle. Here we consider the gravitational wave emission and its polarization as a function of angle which is expected from such sources. We discuss possible correlations between the burst photon luminosity, or the delay between gravitational wave bursts and X-ray flashes, and the polarization degree of the gravitational waves. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The intrinsic fluence and duration distributions of gamma-ray bursts are well represented by log-normal distributions. This allows a bivariate log-normal distribution fit to be made to the BATSE short and long bursts separately. A statistically significant difference between the long and short groups is found. We argue that the effect is probably real. Applying the Cramér's theorem these results lead to some predictions for models of long and short bursts. [ABSTRACT FROM AUTHOR]

The spectra of Gamma-Ray Burst (GRB) emission have been investigated theoretically by a number of authors (e.g., [1, 2, 3]) for different versions of a general fireball-shock scenario [4, 5]. However, the existing models give rather coarse predictions and suffer from many uncertainties. Here we present a refined analytical model of synchrotron-self-Compton (SSC) emission. We take an arbitrary injection spectrum of relativistic particles and let them cool self-consistently, taking into account both synchrotron and inverse Compton (IC) losses and making corrections for the Klein-Nishina cut-off. When two-photon absorption is negligible, the problem is reduced to the single integral equation for the ratio of synchrotron to total losses as a function of particle's energy. The spectra of synchrotron and IC components, as well as the electron distribution, can be derived from this function in a regular way. The low-energy portion of the composite synchrotron spectrum in the fast cooling regime may have spectral index varying from 1/2 to 1, and the spectrum of the IC component is nearly flat around its maximum. [ABSTRACT FROM AUTHOR]

The article discusses a study that examines the residual deformation of basalt fiber and graphene reinforced composites at various load levels with a simple cyclic test method. Other topics discussed include preparation of hybrid composites as a feasible solution to break up the aggregates of nanoparticles, tensile tests conducted on a Zwick Z020 universal testing device, and a chart that outlines the mechanical properties of polyamide 6 matrix hybrid composites.

The article discusses a study on the development of high-performance fiber-reinforced polymer composite with toughened matrix. Topics discussed include characterization of the bending properties according to International Standards Organization 14125:1999, the bending strength of the material with mixed resin, and a graph that shows abided cycle numbers of composites at bending fatigue load in case of 0.95 load factor.

The article looks at a study that examines the impact of basalt fiber reinforcement and the presence of a nanomaterial on the tensile elastic recovery of polyamide 6. Topics mentioned include the strain-stress curves for cyclic loading at increasing load levels, the use of a Zwick Z020 universal loading machine for cyclic tensile tests, and the residual strain estimated following the relaxation time or plastic deformation.