On Hadronic Models for the Anomalous γ\gamma-ray Emission Component in GRB 941017

Gonz\'alez et al. (2003) have reported the discovery of an anomalous radiation component from ~ 1 -- 200 MeV in GRB 941017. This component varies independently of and contains >~ 3 times the energy found in the prompt ~ 50 keV -- 1 MeV radiation component that is well described by the relativistic synchrotron-shock model. Acceleration of hadrons to very high energies by GRBs could give rise to a separate emission component. Two models, both involving acceleration of ultra-high energy cosmic rays with subsequent photomeson interactions, are considered. The first involves a pair-photon cascade initiated by photohadronic processes in the GRB blast wave. Calculations indicate that the cascade produces a spectrum that is too soft to explain the observations. A second model is proposed where photopion interactions in the GRB blast-wave shell give rise to an escaping collimated neutron beam. The outflowing neutrons undergo further photopion interactions to produce a beam of hyper-relativistic electrons that can lose most of their energy during a fraction of a gyroperiod in the Gauss-strength magnetic fields found in the circumburst medium. This secondary electron beam produces a hard synchrotron radiation spectrum that could explain the anomalous component in GRB 941017.Comment: 5 pages, 1 figure, in 2003 Santa Fe Conference on GRB

Beyond the crisis: revisiting emerging Europe’s growth model

Focusing on the nexus between economic growth and the buildup of external vulnerabilities, this paper provides a systematic account of different growth strategies followed in Central and Eastern Europe in 2000-08 and then uses this growth diagnostics to derive implications for a post-crisis recovery. The main findings point to three policy lessons for improving growth sustainability. First, greater reliance on tradable sectors should be the cornerstone of a future growth model. Second, enhancing domestic sources of bank credit funding would contribute to the mitigation of external vulnerabilities and make the domestic financial system more resilient to global financial shocks. Third, prudential and macroeconomic policies will have to be more proactive in managing capital inflows, including funneling these inflows into investment in export-oriented industries.sustainable economic growth, sources of growth, external vulnerabilities

Ultrahigh energy gamma rays: Carriers of cosmological information

Observational data being the basis of contemporary cosmological models are not numerous: Hubble law of redshift for galaxies, element abundances, and observation of cosmic microwave background radiation (MBR). The significance of MBR discovery predicted in the Big-Band model is particularly stressed. Radio astronomical measurements give an information on MBR only near the Earth. Experimental confirmation of evolution of MBR, i.e., its probing in remote epochs, might obviously present a direct verification of the hypothesis of hot expanding Universe. The carriers of similar cosmological information should be particles which, firstly, effectively interact with MBR, and secondly, make it possible to identify unambiguously the epoch of interaction. A possibility to verify a number of cosmological hypotheses by searching the cutoffs in spectra of ultrahigh energy gamma-rays (UHEGR) from extragalactic sources is discussed