111 research outputs found

    Optical counterparts of cosmological GRBs due to heating of ISM in the parent galaxy

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    We investigated influence of cosmological GRB on the surrounding interstellar medium. It was shown that \gamma-radiation from the burst heats interstellar gas to the temperatures > 10^4 K up to the distance \sim 10 pc. For high density ISM optical and UV radiation of the heated gas can be observed on the Eath several years as a GRB`s counterpartComment: 2 pages, 1 figure; presented at the Rome Conference on Gamma Ray Bursts in the Afterglow Ag

    The contribution of perennial fodder crops to the nitrogen balance of agroecosystems in Western Siberia

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    The article presents the results of experiments obtained in stationary experiments on the basis of grain-fallow and grain-grass crop rotations on meadow-chernozem soil in the Omsk region. The influence of spring wheat precursors (alfalfa of the 3rd year of life and fallow) on individual elements of soil fertility and crop yield has been established. It was revealed that when cultivating spring wheat by fallow in the grain-fallow crop rotation, the nitrogen balance (-28 kg/ha) is negative with an intensity of 66 %. When sowing wheat in grain-grass crop rotation on a layer of perennial grasses, the nitrogen balance is positive (+21.0 kg/ha) and the intensity is 119 %. The favorable effect of the legume component in the crop rotation on the nitrogen regime of the soil significantly increased the yield of spring wheat by 0.5 t/ha in comparison with wheat cultivated in the field crop rotation by bare fallow. Under similar conditions, studies were carried out on irrigated meadowchernozem soil in an eight-field stationary grain-grass crop rotation. The removal of nitrogen by the yield of various perennial grasses, as well as the responsiveness of alfalfa, bromus and sweet clover with productivity parameters to the level of nitrogenphosphorus nutrition, were studied. The current mobilization of nitrogen under these conditions under the vegetative brome without fertilizers was 76 kg/ha. When optimizing the phosphate regime of the soil, this indicator increased to 99 kg/ha.  The removal of nitrogen by alfalfa on similar agricultural backgrounds increases due to symbiotically fixed nitrogen, by 89 and 193 kg/ha, respectively, or 2.2 and 2.9 times. Alfalfa and sweet clover responded positively to the improvement of mineral fertilizing conditions (P60N60-160). In alfalfa of the 1-5 year of life the collection of green mass and fodder units increased to 40.56 and 7.00 t/ha, respectively, or by 86 and 54 % relative to the control without fertilizers, with 82.76 GJ of exchange energy per hectare. The productivity of sweet clover of the 2nd year of life increased up to 30.85 t/ha of green mass and 2.83 t/ha of fodder units or by 37 and 17 % relative to the control

    Spectroscopic diagnostics for ablation cloud of tracer-encapsulated solid pellet in LHD

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    In the Large Helical Device (LHD), various spectroscopic diagnostics have been applied to study the ablation process of an advanced impurity pellet, tracer-encapsulated solid pellet (TESPEL). The total light emission from the ablation cloud of TESPEL is measured by photomultipliers equipped with individual interference filters, which provide information about the TESPEL penetration depth. The spectra emitted from the TESPEL ablation cloud are measured with a 250 mm Czerny?Turner spectrometer equipped with an intensified charge coupled device detector, which is operated in the fast kinetic mode. This diagnostic allows us to evaluate the temporal evolution of the electron density in the TESPEL ablation cloud. In order to gain information about the spatial distribution of the cloud parameters, a nine image optical system that can simultaneously acquire nine images of the TESPEL ablation cloud has recently been developed. Several images of the TESPEL ablation cloud in different spectral domains will give us the spatial distribution of the TESPEL cloud density and temperature

    INTEGRAL discovery of non-thermal hard X-ray emission from the Ophiuchus cluster

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    We present the results of deep observations of the Ophiuchus cluster of galaxies with INTEGRAL in the 3-80 keV band. We analyse 3 Ms of INTEGRAL data on the Ophiuchus cluster with the IBIS/ISGRI hard X-ray imager and the JEM-X X-ray monitor. In the X-ray band using JEM-X, we show that the source is extended, and that the morphology is compatible with the results found by previous missions. Above 20 keV, we show that the size of the source is slightly larger than the PSF of the instrument, and is consistent with the soft X-ray morphology found with JEM-X and ASCA. Thanks to the constraints on the temperature provided by JEM-X, we show that the spectrum of the cluster is not well fitted by a single-temperature thermal Bremsstrahlung model, and that another spectral component is needed to explain the high energy data. We detect the high energy tail with a higher detection significance (6.4 sigma) than the BeppoSAX claim (2 sigma). Because of the imaging capabilities of JEM-X and ISGRI, we are able to exclude the possibility that the excess emission comes from very hot regions or absorbed AGN, which proves that the excess emission is indeed of non-thermal origin. Using the available radio data together with the non-thermal hard X-ray flux, we estimate a magnetic field B ~ 0.1-0.2 mu G.Comment: 8 pages, 9 figures, accepted by A&

    INTEGRAL Observations of SS433: Analysis of Precessional and Orbital X-ray Periodicities

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    Hard X-ray INT observations of SS 433 carried out during 2003-2005 years with an analysis of precessional and orbital variability is presented. The width of X-ray eclipse in the 25-50 keV range at the precessional phase ψ=0.1\psi=0.1 (accretion disk is open to observer) is higher than that in the Ginga 18.4-27.6 keV range. This fact suggests existance the presence of hot extended corona around the supercritical accretion disk. Spectrum of hard X-rays in the range 10-200 keV does not change with the precessional phase which also suggests that hard X-ray flux is generated in the hot extended corona around the accretion disk. The parameters of this hot corona are: kT=23-25 keV, \tau = 1.8-2.8. Mass ratio estimated from the analysis of the ingress part of the eclipse light curve is in the range q=m_x/m_v=0.3-0.5.Comment: 5 pages, 10 figure

    An annular gap acceleration model for γ\gamma-ray emission of pulsars

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    If the binding energy of the pulsar's surface is not so high (the case of a neutron star), both the negative and positive charges will flow out freely from the surface of the star. The annular free flow model for γ\gamma-ray emission of pulsars is suggested in this paper. It is emphasized that: (1). Two kinds of acceleration regions (annular and core) need to be taken into account. The annular acceleration region is defined by the magnetic field lines that cross the null charge surface within the light cylinder. (2). If the potential drop in the annular region of a pulsar is high enough (normally the cases of young pulsars), charges in both the annular and the core regions could be accelerated and produce primary gamma-rays. Secondary pairs are generated in both regions and stream outwards to power the broadband radiations. (3). The potential drop in the annular region grows more rapidly than that in the core region. The annular acceleration process is a key point to produce wide emission beams as observed. (4). The advantages of both the polar cap and outer gap models are retained in this model. The geometric properties of the γ\gamma-ray emission from the annular flow is analogous to that presented in a previous work by Qiao et al., which match the observations well. (5). Since charges with different signs leave the pulsar through the annular and the core regions, respectively, the current closure problem can be partially solved.Comment: 11 pages 2 figures, accepted by Chinese Journal of Astronomy and Astrophysic

    The theory of pulsar winds and nebulae

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    We review current theoretical ideas on pulsar winds and their surrounding nebulae. Relativistic MHD models of the wind of the aligned rotator, and of the striped wind, together with models of magnetic dissipation are discussed. It is shown that the observational signature of this dissipation is likely to be point-like, rather than extended, and that pulsed emission may be produced. The possible pulse shapes and polarisation properties are described. Particle acceleration at the termination shock of the wind is discussed, and it is argued that two distinct mechanisms must be operating, with the first-order Fermi mechanism producing the high-energy electrons (above 1 TeV) and either magnetic annihilation or resonant absorption of ion cyclotron waves responsible for the 100 MeV to 1 TeV electrons. Finally, MHD models of the morphology of the nebula are discussed and compared with observation.Comment: 33 pages, to appear in Springer Lecture Notes on "Neutron stars and pulsars, 40 years after the discovery", ed W.Becke
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