Exploring Particle Acceleration in Gamma-Ray Binaries

Binary systems can be powerful sources of non-thermal emission from radio to gamma rays. When the latter are detected, then these objects are known as gamma-ray binaries. In this work, we explore, in the context of gamma-ray binaries, different acceleration processes to estimate their efficiency: Fermi I, Fermi II, shear acceleration, the converter mechanism, and magnetic reconnection. We find that Fermi I acceleration in a mildly relativistic shock can provide, although marginally, the multi-10 TeV particles required to explain observations. Shear acceleration may be a complementary mechanism, giving particles the final boost to reach such a high energies. Fermi II acceleration may be too slow to account for the observed very high energy photons, but may be suitable to explain extended low-energy emission. The converter mechanism seems to require rather high Lorentz factors but cannot be discarded a priori. Standard relativistic shock acceleration requires a highly turbulent, weakly magnetized downstream medium; magnetic reconnection, by itself possibly insufficient to reach very high energies, could perhaps facilitate such a conditions. Further theoretical developments, and a better source characterization, are needed to pinpoint the dominant acceleration mechanism, which need not be one and the same in all sources.Comment: 7 pages, 1 figure, proceedings of the 13th ICATPP Conference on Astroparticle, Particle, Space Physics and Detectors for Physics Applications (Villa Olmo, Como 3-7 October 2011

Electromagnetic radiation initiated by hadronic jets from microquasars in the ISM

Microquasars are potential candidates to produce a non-negligible fraction of the observed galactic cosmic rays. The protons accelerated at the jet termination shock interact with the interstellar medium and may produce detectable fluxes of extended emission at different energy bands: high-energy and very high-energy gamma-rays produced by neutral pion-decay, synchrotron and bremsstrahlung emission in a wide energy range generated by the secondary electrons produced by charged pion-decay. We discuss the association between this scenario and some of the unidentified EGRET sources in the galactic plane.Comment: (1)Universitat de Barcelona (2)Max Planck institute fur kernphysik, 11 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

Broad-band electromagnetic radiation from microquasars interacting with ISM

Microquasars (MQs) are galactic objects with relativistic jets that constitute a source population which can be responsible for production of a non-negligible fraction of the observed galactic cosmic rays. These relativistic protons, associated with the termination of the jet, interact with the interstellar medium and, at certain surrounding conditions, may lead to production of detectable fluxes of high-energy and very high-energy gamma-rays. This radiation is accompanied by the broad-band emission of secondary electrons from decays of $\pi^\pm$-mesons produced through synchrotron, bremstrahlung and inverse Compton process. The features of broad-band emission initiated by proton-proton (pp) interactions in such a scenario is discussed in the context of the strategy of search for counterparts of high-energy and very high-energy gamma-ray sources in the galactic plane.Comment: High Energy Gamma-Ray Astronomy: 2nd International Symposium, Proceedings of the conference held 26-30 July 2004 in Heidelberg (Germany). Edited by Felix A. Aharonian, Heinz J. Volk, and Dieter Horns. AIP Conference Proceedings, Volume 745. New York: American Institute of Physics, 2005., p.317-32

Patenting and research and development : a global view

Using a new global data base on patents and innovation inputs, the authors examine the process of knowledge creation measured by the dynamic relationship between research and development and U.S. patents granted. They confirm at the country level the recurrent micro-level finding of a strong relationship between the two and estimate the OECD elasticity to be effectively equal to one. This conflicts with the frequent micro-level finding of strongly diminishing returns in knowledge generation and suggests the importance of knowledge spillover effects measurable only at the aggregate level. Developing countries, however, do show diminishing returns. The authors then explain the differences in spillovers between the OECD and developing countries by testing for the impact of measures of the functioning of the national innovation system-the set of institutions and agents that create and disseminate knowledge. Across the entire sample education, security of intellectual property rights, and in some specifications, the quality of research institutions and their interaction with the private sector, affect the transformation of research and development into patents.Scientific Research&Science Parks,Science Education,Economic Theory&Research,Real&Intellectual Property Law,Technology Industry

Spatial dimensions of trade liberalization and economic convergence : Mexico 1985-2002

This paper studies the spatial dimension of growth in Mexico over the past three decades. The literature on regional economic growth shows a decrease in regional dispersion from 1970 to 1985, and a sharp increase afterward coinciding with the trade liberalization of the Mexican economy. Using spatial econometric, tools the authors analyze how the process of convergence/divergence has mapped spatially and whether it makes sense to talk about spatial regions in Mexico. Although the rich North-poor South dichotomy has dominated this phenomenon, interesting patterns emerge. Namely the distribution of growth after Mexico's post-liberalization seems to be much less associated with distance to the United States than the authors had initially expected.Economic Theory&Research,Urban Governance and Management,Regional Governance,Inequality,Economic Conditions and Volatility