142 research outputs found

    Scientific publishing in Armenia

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    Developing New Masters Program on Library and information science for the LIS faculties of Armenia, Georgia and Uzbekistan

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    Starting from January 2009 six organizations from Armenia, Georgia and Uzbekistan in partnership with the European Union universities are participating in a three year multi-national joint European project “Developing New Masters Programme in Library and Information Science”, funded and managed by the European Union “Tempus-Tacis” programme. LIS education in these three republics needs root-and-branch modernization, as the existing curricula are in their form, content and teaching approaches still based on the 1960s practices. The lectures are heavily overloaded with the Soviet library management traditions, which are already outdated. The curricula to be developed will be based on accepted best practice in European partner Universities’ LIS faculties, and it is anticipated that the subjects will meet the requirements of the Bologna and related agreements. Lifelong learning component and advanced skills courses will also be introduced. In the European Union, many library schools also teach archival studies. The discipline is increasingly sharing modules with library and information science in the electronic age so this has also been included in the project. Implementation of the new curricula will directly affect assist in building ‘Knowledge Societies’ in these three former Soviet republics

    International conference "Information technologies in education in the 21st century": Conference proceedings.

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    Proceedings of a conference which concluded TEMPUS project JEP 25008_200

    Constraints on the intergalactic magnetic field using Fermi-LAT and H.E.S.S. blazar observations

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    Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) the IGMF can be obtained from observations of high-energy gamma rays from distant blazars. Gamma rays interact with the extragalactic background light to produce electron-positron pairs, which can subsequently initiate electromagnetic cascades. The γ\gamma-ray signature of the cascade depends on the IGMF since it deflects the pairs. Here we report on a new search for this cascade emission using a combined data set from the Fermi Large Area Telescope and the High Energy Stereoscopic System. Using state-of-the-art Monte Carlo predictions for the cascade signal, our results place a lower limit on the IGMF of B>7.1×1016B > 7.1\times10^{-16} G for a coherence length of 1 Mpc even when blazar duty cycles as short as 10 yr are assumed. This improves on previous lower limits by a factor of 2. For longer duty cycles of 10410^4 (10710^7) yr, IGMF strengths below 1.8×10141.8\times10^{-14} G (3.9×10143.9\times10^{-14} G) are excluded, which rules out specific models for IGMF generation in the early universe.Comment: 20 pages, 7 figures, 4 tables. Accepted for publication in ApJ Letters. Auxiliary data is provided in electronic format at https://zenodo.org/record/801431

    HESS J1809-193: a halo of escaped electrons around a pulsar wind nebula?

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    Context. HESS J1809-193 is an unassociated very-high-energy γ\gamma-ray source located on the Galactic plane. While it has been connected to the nebula of the energetic pulsar PSR J1809-1917, supernova remnants and molecular clouds present in the vicinity also constitute possible associations. Recently, the detection of γ\gamma-ray emission up to energies of \sim100 TeV with the HAWC observatory has led to renewed interest in HESS J1809-193. Aims. We aim to understand the origin of the γ\gamma-ray emission of HESS J1809-193. Methods. We analysed 93.2 h of data taken on HESS J1809-193 above 0.27 TeV with the High Energy Stereoscopic System (H.E.S.S.), using a multi-component, three-dimensional likelihood analysis. In addition, we provide a new analysis of 12.5 yr of Fermi-LAT data above 1 GeV within the region of HESS J1809-193. The obtained results are interpreted in a time-dependent modelling framework. Results. For the first time, we were able to resolve the emission detected with H.E.S.S. into two components: an extended component that exhibits a spectral cut-off at \sim13 TeV, and a compact component that is located close to PSR J1809-1917 and shows no clear spectral cut-off. The Fermi-LAT analysis also revealed extended γ\gamma-ray emission, on scales similar to that of the extended H.E.S.S. component. Conclusions. Our modelling indicates that based on its spectrum and spatial extent, the extended H.E.S.S. component is likely caused by inverse Compton emission from old electrons that form a halo around the pulsar wind nebula. The compact component could be connected to either the pulsar wind nebula or the supernova remnant and molecular clouds. Due to its comparatively steep spectrum, modelling the Fermi-LAT emission together with the H.E.S.S. components is not straightforward. (abridged)Comment: 14 pages, 10 figures. Accepted for publication in A&A. Corresponding authors: Vikas Joshi, Lars Mohrman

    A deep spectromorphological study of the γ\gamma-ray emission surrounding the young massive stellar cluster Westerlund 1

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    Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy is a prime candidate for studying this hypothesis. While the very-high-energy γ\gamma-ray source HESS J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. We aim to identify the physical processes responsible for the γ\gamma-ray emission around Westerlund 1 and thus to better understand the role of massive stellar clusters in the acceleration of Galactic CRs. Using 164 hours of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the γ\gamma-ray emission of HESS J1646-458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. We detected large-scale (2\sim 2^\circ diameter) γ\gamma-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with γ\gamma-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and is uniform across the entire source region. We did not find a clear correlation of the γ\gamma-ray emission with gas clouds as identified through H I and CO observations. We conclude that, of the known objects within the region, only Westerlund 1 can explain the bulk of the γ\gamma-ray emission. Several CR acceleration sites and mechanisms are conceivable, and discussed in detail. (abridged)Comment: 15 pages, 9 figures. Corresponding authors: L. Mohrmann, S. Ohm, R. Rauth, A. Specoviu

    A MeerKAT, e-MERLIN, H.E.S.S. and Swift search for persistent and transient emission associated with three localised FRBs

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    H.E.S.S. follow-up observations of GRB221009A

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    GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, >>\!100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nights after the initial GRB detection, after applying atmospheric corrections. The combined observations yield an integral energy flux upper limit of ΦUL95%=9.7×1012 ergcm2s1\Phi_\mathrm{UL}^{95\%} = 9.7 \times 10^{-12}~\mathrm{erg\,cm^{-2}\,s^{-1}} above Ethr=650E_\mathrm{thr} = 650 GeV. The constraints derived from the H.E.S.S. observations complement the available multiwavelength data. The radio to X-ray data are consistent with synchrotron emission from a single electron population, with the peak in the SED occurring above the X-ray band. Compared to the VHE-bright GRB190829A, the upper limits for GRB221009A imply a smaller gamma-ray to X-ray flux ratio in the afterglow. Even in the absence of a detection, the H.E.S.S. upper limits thus contribute to the multiwavelength picture of GRB221009A, effectively ruling out an IC dominated scenario.Comment: 10 pages, 4 figures. Accepted for publication in APJL. Corresponding authors: J. Damascene Mbarubucyeye, H. Ashkar, S. J. Zhu, B. Reville, F. Sch\"ussle

    Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S

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    Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of gamma-ray emission on angular scales > 2 deg poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended gamma-ray emission around the Geminga pulsar with a radius of at least 3 deg in the energy range 0.5-40 TeV. We find no indications for statistically significant asymmetries or energy-dependent morphology. A flux normalisation of (2.8±0.7)×1012(2.8\pm0.7)\times10^{-12} cm2^{-2}s1^{-1}TeV1^{-1} at 1 TeV is obtained within a 1 deg radius region around the pulsar. To investigate the particle transport within the halo of energetic leptons around the pulsar, we fitted an electron diffusion model to the data. The normalisation of the diffusion coefficient obtained of D0=7.61.2+1.5×1027D_0 = 7.6^{+1.5}_{-1.2} \times 10^{27} cm2^2s1^{-1}, at an electron energy of 100 TeV, is compatible with values previously reported for the pulsar halo around Geminga, which is considerably below the Galactic average.Comment: 16 pages, 15 figures, 7 tables. Accepted for publication in Astronomy & Astrophysic
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