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51.
S. Karakula W. Tkaczyk F. Giovannelli 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
In the spherical accretion onto massive objects, the matter may be heated up to temperatures as high as 1012 °K. In such a hot plasma, the thermal bremsstrahlung (e-e and e-p) and π° decay from inelastic collisions of protons are the main γ-ray sources. We determined the γ -ray production spectra from the π° decay and from bremsstrahlung for different temperatures. The expected γ-ray spectra were evaluated too in order to fit experimental data. We have fitted COS B data from 3C 273 using a two temperatures plasma model. The best fit is for
(M8 is the black hole mass in 108 M) which gives
. The hard X-ray measurements do not contradict the bremsstrahlung spectrum. 相似文献
Full-size image (1K)
52.
D.L. Bertsch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
The Gamma Ray Observatory (GRO) is an approved NASA mission, programmed for launch in 1988. Its complement of four detectors has established goals: 1) to study the nature of compact γ-ray sources such as neutron stars and black holes, or objects whose nature is yet to be understood; 2) to search for evidence of nucleosynthesis especially in the regions of supernovae; 3) to study structural features and dynamical properties of our galaxy; 4) to explore other galaxies, especially the extraordinary types such as radio, Seyferts, and quasars; and 5) to study cosmological effects by examining the diffuse radiation in detail. This paper discusses the design, objectives, and expected scientific results of each of the GRO instruments in view of the GRO mission goals. 相似文献
53.
A. T. Altyntsev V. V. Grechnev G. N. Zubkova N. N. Kardapolova S. V. Lesovoi Y. M. Rosenraukh T. A. Treskov 《Space Science Reviews》1994,68(1-4):251-252
We present the results of the first observations of spike-like phenomena with the Siberian Solar Radio Telescope (SSRT) in the one-dimensional mode at the frequency of 5.7 GHz with high spatial and temporal resolutions. 相似文献
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Owing to its outstanding mechanical properties, γ-TiAl is desirable materials for crossgeneration aero-engines. Nearly 70 years of exploration have made it into the initial application.However, the intrinsic brittleness of γ-TiAl is still a critical obstacle to its large-scale applications.In this context, researchers have made many attempts to study the machinability of γ-TiAl. At present, existing relevant reviews have mostly discussed the processing methods of γ-TiAl. Hence, there is still a ... 相似文献
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W.J. Azzam M.J. Alothman N. Guessoum 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,44(11):1354-1358
Several luminosity relations currently exist for long gamma-ray bursts (GRBs). Some were derived from the light curves; others were obtained from the spectra. In this study, we consider two of these luminosity relations: the time-lag, τlag, relation and the variability, V, relation and investigate their possible dependence on (or “evolution” with) the redshift, z. 相似文献
58.
M.S. Skidmore R.M. Ambrosi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,44(9):1019-1029
Understanding the evolution of Mars requires determining the composition of the surface and atmosphere of the planet. The European Space Agency’s ExoMars rover mission, which is expected to launch in 2016, is part of the Aurora programme. The instruments on the rover will search for evidence of life on Mars and will map a sub-section of the Martian surface, extracting compositional information. Currently our understanding of the bulk composition (and mineralogy) of Mars relies on orbital data from instruments on-board satellites such as 2001 Mars Odyssey, Mars Reconnaissance Orbiter and Mars Express, in addition to in-situ instrumentation on rovers such as Spirit and Opportunity. γ-ray spectroscopy can be used to determine the composition of Mars, but it has yet to be successfully carried out in-situ on Mars. This study describes some of the results obtained from the γ-ray spectrometer on 2001 Mars Odyssey during solar proton events and discusses whether the increased emissions are useful in γ-ray spectroscopy. The study shows that although increased γ-ray emissions were expected from the Martian surface during a solar proton event, they were not detected from orbit probably due to insufficient signal-to-background. However, this does not preclude the possibility of measuring changes in γ-ray flux corresponding to changes in solar activity on the surface of the planet. 相似文献
59.
K. Watanabe R.P. Lin S. Krucker R.J. Murphy G.H. Share M.J. Harris M. Gros Y. Muraki T. Sako Y. Matsubara T. Sakai S. Shibata J.F. Valds-Galicia L.X. Gonzlez A. Hurtado O. Musalem P. Miranda N. Martinic R. Ticona A. Velarde F. Kakimoto Y. Tsunesada H. Tokuno S. Ogio 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,44(7):789-793
Relativistic neutrons were observed by the neutron monitors at Mt. Chacaltaya and Mexico City and by the solar neutron telescopes at Chacaltaya and Mt. Sierra Negra in association with an X17.0 flare on 2005 September 7. The neutron signal continued for more than 20 min with high statistical significance. Intense emissions of γ-rays were also registered by INTEGRAL, and during the decay phase by RHESSI. We analyzed these data using the solar-flare magnetic-loop transport and interaction model of Hua et al. [Hua, X.-M., Kozlovsky, B., Lingenfelter, R.E. et al. Angular and energy-dependent neutron emission from solar flare magnetic loops, Astrophys. J. Suppl. Ser. 140, 563–579, 2002], and found that the model could successfully fit the data with intermediate values of loop magnetic convergence and pitch-angle scattering parameters. These results indicate that solar neutrons were produced at the same time as the γ-ray line emission and that ions were continuously accelerated at the emission site. 相似文献
60.
P.A. Caraveo G.F. Bignami L. Vigroux J.A. Paul R.C. Lamb 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
Dedicated X-ray, optical and radio observations aimed at the identification of the bright γ-ray source 2CG195+04 (GEMINGA) are presented. A very promising candidate is found and its properties are discussed in the context of possible astrophysical scenarios. 相似文献