Search Publications
Catalog of short gamma-ray transients detected in the SPI/INTEGRAL experiment
Minaev, P. Yu.; Pozanenko, A. S.; Grebenev, S. A. +1 more
We analyzed the data obtained by the SPI telescope onboard the INTEGRAL observatory to search for short transient events with a duration from 1 ms to a few tens of seconds. An algorithm for identifying gamma-ray events against the background of a large number of charged particle interactions with the detector has been developed. The classification…
Cutoff in the hard X-ray spectra of the ultraluminous X-ray sources HoIX X-1 and M82 X-1
Sazonov, S. Yu.; Lutovinov, A. A.; Krivonos, R. A.
Using data from the XMM-Newton and INTEGRAL observatories, we have detected a cutoff at energies above 10 keV in the X-ray spectra of the ultraluminous X-ray sources HoIX X-1 and M82 X-1. The spectra obtained can be described by amodel of Comptonization of radiation in a gas cloud of moderate temperature ( kT ∼ 2-3 keV) and high optical depth ( τ …
Stellar content of the metal-poor galaxy DDO 68
Tikhonov, N. A.; Galazutdinova, O. A.; Lebedev, V. S.
Based on archival Hubble Space Telescope ACS/WFC images, we have performed stellar photometry for the metal-poor galaxy DDO 68. The apparent distributions of stars of different ages and stellarmetallicity determinations indicate that DDO68 is a systemof two galaxies that have different stellar metallicities ( Z = 0.004 and 0.001) and are in the st…
Stellar content and distances to the isolated spiral galaxies NGC 6503 and NGC 6946
Tikhonov, N. A.
Based on archival Hubble Space Telescope images, we have performed stellar photometry of several fields in the isolated spiral galaxies NGC 6503 and NGC 6946 with high peculiar velocities. Based on the TRGB method, we have determined the distances to the galaxies: D = 6.30 ± 0.10 Mpc for NGC 6503 and D = 6.72 ± 0.15 Mpc for NGC 6946. The current s…
Dust evolution in the dwarf galaxy Holmberg II
Wiebe, D. S.; Lozinskaya, T. A.; Egorov, O. V. +1 more
A detailed photometric study of star-forming regions (SFRs) in the galaxy Holmberg II has been carried out using the archival observational data from the far infrared to the ultraviolet obtained with the GALEX, Spitzer, and Herschel telescopes. Spectroscopic observations with the 6-m BTA telescope (Special Astrophysical Observatory of the Russian …
Reverse-current effect in present-day models of solar flares: Theory and high-accuracy observations
Gritsyk, P. A.; Somov, B. V.
We propose an accurate analytical model for the source of hard X-ray emission from a flare in the form of a "thick target" with a reverse current to explain the results of present-day observations of solar flares onboard the GOES, Hinode, RHESSI, and TRACE satellites. The model, one-dimensional in coordinate space and two-dimensional in velocity s…
Measurements of the cosmic X-ray background of the Universe and the MVN experiment
Revnivtsev, M. G.
The paper is devoted to studying the cosmic X-ray background (CXB) of the Universe in the energy range 1-100 keV and to the prospects for its investigation by means of the projected MVN (Monitor Vsego Neba) experiment. The nature of the CXB and its use for studying the cosmological evolution of black holes are briefly discussed. The bulk of the pa…
Relation between the X-ray and optical luminosities in binary systems with accreting nonmagnetic white dwarfs
Revnivtsev, M. G.; Suleimanov, V. F.; Filippova, E. V.
We investigate the relation between the optical ( g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the …
Broadband spectrum of the total X-ray emission from the galaxy M31
Sunyaev, R. A.; Tsygankov, S. S.; Revnivtsev, M. G. +2 more
We present the results of measurements of the total X-ray flux from the Andromeda galaxy (M31) in the 3-100 keV band based on data from the RXTE/PCA, INTEGRAL/ISGRI, and SWIFT/BAT space experiments. We show that the total emission from the galaxy has a multicomponent spectrum whose main characteristics are specified by binaries emitting in the opt…
Kinematic analysis of stellar radial velocities by the spherical harmonics
Tsvetkov, A. S.; Vityazev, V. V.; Trofimov, D. A.
A method for a kinematic analysis of stellar radial velocities using spherical harmonics is proposed. This approach does not depend on the specific kinematic model and allows both low-frequency and high-frequency kinematic radial velocity components to be analyzed. The possible systematic variations of distances with coordinates on the celestial s…