Search Results - (Author, Cooperation:S. A. Grebenev)
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1Latest Papers from Table of Contents or Articles in PressS. A. Grebenev ; A. A. Lutovinov ; S. S. Tsygankov ; C. Winkler
Nature Publishing Group (NPG)
Published 2012Staff ViewPublication Date: 2012-10-19Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsPublished by: -
2Latest Papers from Table of Contents or Articles in PressR. Diehl ; T. Siegert ; W. Hillebrandt ; S. A. Grebenev ; J. Greiner ; M. Krause ; M. Kromer ; K. Maeda ; F. Ropke ; S. Taubenberger
American Association for the Advancement of Science (AAAS)
Published 2014Staff ViewPublication Date: 2014-08-02Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsPublished by: -
3Articles: DFG German National LicensesStaff View
ISSN: 1562-6873Keywords: pulsars ; neutron stars ; X-ray sources ; scatteringSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: 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 ResourceURL: -
4Articles: DFG German National LicensesStaff View
ISSN: 1562-6873Keywords: neutron stars ; pulsars ; X-ray sourcesSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: 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 ResourceURL: -
5Articles: DFG German National LicensesPavlinsky, M. N. ; Grebenev, S. A. ; Mazov, P. A. ; Dekhanov, I. A. ; Ryvkin, D. B. ; Sunyaev, R. A. ; Surtaev, V. I. ; Mokrousov, N. V. ; Glushenko, A. G. ; Yampol’skii, S. I. ; Novikov, A. D.
Springer
Published 2000Staff ViewISSN: 1562-6873Keywords: X-ray monitor ; gamma-ray bursts ; bursters ; Galactic center ; coded apertureSource: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: Abstract The Spin-X wide-field X-ray monitor of the Spectrum-X-Gamma astrophysical observatory, which is based on the principle of a coded-aperture telescope, is designed to detect and localize cosmic gammaray-burst (GRB) sources; to survey large areas of the sky in search of new transients; and to carry out long-term observations of bright Galactic sources, including X-ray bursters. The monitor consists of two noncoaxial identical modules, Spin-X1 and Spin-X2, which together cover 6.8% of the sky. The high-apogee, four-day orbit of the Spectrum-XG satellite allows the instrument to be in observing mode more than 50% of the time. Having simulated the rate of GRB detection by Spin-X, we show that extrapolating BATSE 50–300-keV average data on the number of GRBs, their duration, and their mean energy spectrum to the X-ray energy band leads to disagreement with the observed detection rate of GRBs in the X-ray band. The number of GRBs that can be detected and localized with an accuracy r≤3′ (3σ) (the error-circle radius) by Spin-X is estimated to be ten bursts per year. We present data on the Spin-X sensitivity achievable during long-term observations of persistent and transient sources and on its sensitivity to X-ray bursts from Galactic sources in the 2–30-keV energy band.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1562-6873Source: Springer Online Journal Archives 1860-2000Topics: PhysicsNotes: 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 ResourceURL: