Mikhail G. Revnivtsev

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We report the results of identification of 8 hard X-ray sources discovered by the INTEGRAL observatory during the ongoing all-sky survey. These sources have been observed by Chandra. In 6 cases a bright X-ray source was found within the INTEGRAL localization region, which enabled us to unambigously identify 5 of the objects with nearby galaxies, implying(More)
Two component X–ray spectra (soft multicolor black body plus harder power law) are frequently observed from accreting black holes. These components are presumably associated with the different parts of the accretion flow (optically thick and optically thin respectively) in the vicinity of the compact source. Timing analysis further suggests that most of the(More)
Using the RXTE/PCA data we study the fast variability of the reflected emission in the soft spectral state of Cyg X-1 by means of Fourier frequency resolved spectroscopy. We find that the rms amplitude of variations of the reflected emission has the same frequency dependence as the primary radiation down to time scales of < ∼ 30−50 msec. This might indicate(More)
We analyzed RXTE/PCA observations of Cyg X–1 from 1996–1998.We found a tight correlation between the characteristic noise frequencies (e.g. the break frequency νbr) and the spectral parameters in the low spectral state. The amplitude of reflection increases and the spectrum of primary radiation steepens as the noise frequency increases (νbr changes by a(More)
Based on the analysis of a large sample of RXTE/PCA observations of several black hole binaries in the low spectral state we show that a correlation exists between the spectral parameters and characteristic noise frequency. In particular, the amplitude of reflection increases and the slope of Comptonized radiation steepens as the noise frequency increases.(More)
An unresolved X-ray glow (at energies above a few kiloelectronvolts) was discovered about 25 years ago and found to be coincident with the Galactic disk-the Galactic ridge X-ray emission. This emission has a spectrum characteristic of a approximately 10(8) K optically thin thermal plasma, with a prominent iron emission line at 6.7 keV. The gravitational(More)
X–ray transients provide unique opportunity to probe accretion regimes of at a vastly different accretion rates. We analyze a collection of the RXTE observations (Galactic Center scans, ASM monitoring and a pointed observation) of enigmatic transient source high mass X-ray binary V4641 Sgr and argue that they broadly support the hypothesis that giant(More)
Aims. We study the spectrum of the cosmic X-ray background (CXB) in energy range ∼5-100 keV. Methods. Early in 2006 the INTEGRAL observatory performed a series of four 30ksec observations with the Earth disk crossing the field of view of the instruments. The modulation of the aperture flux due to occultation of extragalactic objects by the Earth disk was(More)
The electron-positron annihilation spectrum observed by SPI/INTEGRAL during deep Galactic Center region exposure is reported. The line energy (510.954±0.075 keV) is consistent with the unshifted annihilation line. The width of the annihilation line is 2.37±0.25 keV (FWHM), while the strength of the ortho-positronium continuum suggests that the dominant(More)
We report the association of the recently discovered hard X-ray source IGR J17475−2822 with the giant molecular cloud Sgr B2 in the Galactic Center region. The broad band (3–200 keV) spectrum of the source constructed from data of different observatories strongly supports the idea that the X-ray emission of Sgr B2 is Compton scattered and reprocessed(More)