Spectral Lags Explained as Scattering from Accelerated Scatterers

A quantitative theory of spectral lags for $\gamma$-ray bursts (GRBs) is given. The underlying hypothesis is that GRB subpulses are photons that are scattered into our line of sight by local concentrations of baryons that are accelerated by radiation pressure. For primary spectra that are power laws with exponential cutoffs, the width of the pulse and its fast rise, slow decay asymmetry is found to increase with decreasing photon energy, and the width near the exponential cutoff scales approximately as $E_{ph}^{-\eta}$, with $\eta\sim 0.4$, as observed. The spectral lag time is naturally inversely proportional to luminosity, all else being equal, also as observed.Comment: 2 figure

How unusual is XRF 060218 ?

Light curves are calculated for an off-axis observer due the scattering of primary radiation by extended baryonic material. The unusually long duration and the chromaticity of the light curves above several KeV of XRF 060218 can be explained as a result of the acceleration of the baryonic scattering material by the primary radiation. The observed light curves by our model and detailed fits to the data are presented. The model predicts that $\sim 4\times 10^{48}$ ergs are put into accelerated, mildly relativistic baryons by the radiation pressure at large radii from the central engine. It is suggested that the emission below 3 KeV, which lies {\it below} the Amati relation, is a baryon contaminated fireball.Comment: 7 pages, 5 figures, Appeared in ApJL, Volume 713, Issue 1, pp. L55, 201

Waiting for the Big One: A New Class of SGR Outbursts?

It is suggested that magnetars eventually become unstable to a dynamic overturning instability that destroys most of their dipole moment in a single event. It is further suggested that such an instability would produce a supergiant version of the largest soft gamma ray bursts that have thus far been observed, and that they could be observed out to tens or even $10^2$ Mpc. Persistent emission and afterglows from the fireball might confirm positive identification with nearby galaxies and perhaps provide other distinguishing features as well.Comment: to appear in M.N.R.A.

Standard GRB, Dirty Fireballs, and the Excluded Middle

It is shown that the contribution of faint gamma-ray bursts (GRB) to the total allsky GRB energy flux is small. The allsky flux of GRB appears to be $5.3 \times 10^{-3}$ erg/$\rm cm^2 y$, with little additional component hidden within weak or otherwise undetectable GRB. This significantly constrains physical models of GRB and dirty fireballs, suggesting a rather sharp dichotomy between them should the latter exist.Comment: to appear in The Astrophysical Journa

First foot prints of chemistry on the shore of the Island of Superheavy Elements

Chemistry has arrived on the shore of the Island of Stability with the first chemical investigation of the superheavy elements Cn, 113, and 114. The results of three experimental series leading to first measured thermodynamic data and qualitatively evaluated chemical properties for these elements are described. An interesting volatile compound class has been observed in the on-line experiments for the elements Bi and Po. Hence, an exciting chemical study of their heavier transactinide homologues, elements 115 and 116 is suggested.Comment: Invited Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

indigenous perspectives on global norms

Ever since Evo Morales Ayma became Bolivia's first indigenous president in 2006 and the promulgation of a human-rights-enhancing Constitution (2009) thereafter, indigenous peoples’ rights were gradually recognised. Yet, with the increasing demand for natural resources, indigenous communities have been adversely affected by the state's neo-extractivist policies. While global indigenous rights norms protect their fundamental rights, legal-implementation processes in the country's lowlands reveal dilemmas in terms of the value of laws in practice as well as its reinterpretation on the ground. Namely, in the communities, different positions and camps have emerged in terms of the role and functions of participatory rights. Despite the potential of the latter in strengthening collective-rights regimes and self-determination, community leaders, advisers and other members report how such processes fracture and weaken decision-making mechanisms and human rights claims

Graphical modelling of multivariate time series

We introduce graphical time series models for the analysis of dynamic relationships among variables in multivariate time series. The modelling approach is based on the notion of strong Granger causality and can be applied to time series with non-linear dependencies. The models are derived from ordinary time series models by imposing constraints that are encoded by mixed graphs. In these graphs each component series is represented by a single vertex and directed edges indicate possible Granger-causal relationships between variables while undirected edges are used to map the contemporaneous dependence structure. We introduce various notions of Granger-causal Markov properties and discuss the relationships among them and to other Markov properties that can be applied in this context.Comment: 33 pages, 7 figures, to appear in Probability Theory and Related Field