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  • 1
    Electronic Resource
    Electronic Resource
    An apparently normal γ -ray burst with an unusually low luminosity (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 430 (2004), S. 646-648 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Much of the progress in understanding γ-ray bursts (GRBs) has come from studies of distant events (redshift z ≈ 1). In the brightest GRBs, the γ-rays are so highly collimated that the events can be seen across the Universe. It has long been suspected that the nearest and most ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02748
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  • 2
    Electronic Resource
    Electronic Resource
    Spectral variability of the X-ray pulsar Hercules X-1 (2000)
    Springer
    Astronomy letters 26 (2000), S. 691-698 
    Details
    ISSN: 1562-6873
    Keywords: pulsars ; neutron stars ; X-ray sources ; scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present the results of our comparative timing and spectral analysis of the high and low (off) states in the X-ray pulsar Her X-1 based on data from the ART-P telescope onboard the Granat observatory. A statistically significant (several mCrab) persistent flux with a simple power-law spectrum was detected during the low state. The spectral slope changed from observation to observation by almost a factor of 2. Pulsations were detected only during the high state of the source, when its flux was a factor of ∼25 larger than the low-state flux. The spectral shape of Her X-1 in its high state was complex, with the parameters depending on pulse phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1323276
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray variability of the pulsar Vela X-1 as observed with ART-P/Granat (2000)
    Springer
    Astronomy letters 26 (2000), S. 765-771 
    Details
    ISSN: 1562-6873
    Keywords: neutron stars ; pulsars ; X-ray sources
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the X-ray pulsar Vela X-1 with the ART-P telescope onboard the Granat Observatory are presented. Variability on a time scale of several thousand seconds was detected; intensity variations are shown to be accompanied by changes in the source’s spectrum. The hardness was also found to be highly variable on a scale of one pulsation period. The source’s spectrum exhibits an absorption feature at energy ∼7 keV, which is apparently attributable to cyclotron scattering/absorption in the neutron-star magnetic field. Weak persistent emission was detected during an X-ray eclipse, which probably resulted from the scattering of pulsar emission in the stellar wind from an optical star.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1331156
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  • 4
    Electronic Resource
    Electronic Resource
    ART-P/Granat observations of the X-ray pulsar 4U0115+634 during the outburst in February 1990 (2000)
    Springer
    Astronomy letters 26 (2000), S. 1-8 
    Details
    ISSN: 1562-6873
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the transient X-ray pulsar 4U0115+634 with the ART-P telescope aboard the Granat Observatory during the outburst in February 1990 are presented. The source exhibited a strong, regular and irregular variability, including X-ray bursts of duration 300–500 s. Two absorption features were detected in the source's photon spectrum at ∼12 and ∼22 keV, which were interpreted as the lines of resonance scattering of its emission at the first and second cyclotron harmonics. The magnetic-field strength B on the neutron-star surface that corresponds to these lines is ∼1.3 × 1012 G. The ratio of the line energies slightly differs from the harmonic ratio 1: 2. Moreover, this ratio and the line energies themselves vary appreciably with phase on a time scale of one pulsation period. The dependence of other spectral parameters for 4U0115+634 on pulse phase is investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.20363
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