102 citations · 244 across the 20 of their papers we have counts for
16 papers · 1 filter
X-ray and gamma-ray timing of GRB 180720B, GRB 181222B, GRB 211211A and GRB 220910A observed with Fermi and ASIM
M. D. Caballero-Garcia, E. Gogus, J. Navarro-Gonzalez +20
We present a timing study of the gamma and X-ray observations and analysis of a sample of bright gamma-ray bursts (GRBs; i.e. GRB 180720B, GRB 181222B, GRB 211211A and GRB 220910A)…
The Nature of the Emission Spectrum of NGC 7793 P13: modeling the atmosphere of the donor star
A. S. Vinokurov, A. E. Kostenkov, K. E. Atapin +1
We continue to study the ultra-luminous X-ray source NGC 7793 P13 in the optical range. In this work, we are testing the model of a spherically symmetric wind atmosphere of the don…
I-band photometry of the quiescent black hole X-ray nova GROJ0422+32=V518 Per: modelling of the orbital light curve and estimation of the black hole mass
A. Cherepashchuk, T. Khruzina, K. Atapin
We present new photometric observations of the X-ray nova GROJ0422+32 (V518 Per) carried out in the I band over 14 nights in 2020 -- 2023. We had to revise the orbital period o…
Simultaneous X-ray/UV observations of ultraluminous X-ray source Holmberg II X-1 with Indian space mission AstroSat
A. Vinokurov, K. Atapin, O. P. Bordoloi +11
We present the results of 8 epochs of simultaneous UV and X-ray observations of the highly variable ultraluminous X-ray source (ULX) Holmberg II X-1 with AstroSat -- Indian multiwa…
Optical Counterparts of ULXs in Two Dwarf Galaxies: NGC 4861 and NGC 4449
M. Ozdogan Ela, A. Akyuz, N. Aksaker +7
We present the results of a search for optical candidates of Ultraluminous X-ray sources (ULXs) in two dwarf galaxies: NGC 4861 and NGC 4449 using Hubble Space Telescope {\it HST}…
NGC 5474 X-1: a neutron star ULX in an old stellar cluster?
Kirill Atapin, Alexander Vinokurov, Arkadiy Sarkisyan +4
We present the optical and X-ray study of the ultraluminous X-ray source (ULX) NGC 5474 X-1. The X-ray spectrum taken during the bright state of the source ($L_X \sim 2\times10^{40…
Observations of ultraluminous X-ray sources with the 6-m telescope of the SAO RAS
A. Vinokurov, K. Atapin, Y. Solovyeva +2
The nature of ultraluminous X-ray sources (ULXs) is not yet fully understood but it can be done in the most efficient way by analyzing its optical emission and environment. We pres…
Optical Counterpart to the Ultraluminous X-Ray Source in the UGC6456 Galaxy
Alexander Vinokurov, Kirill Atapin, Yulia Solovyeva
We report the identification of the optical counterpart to the transient ultraluminuos X-ray source in the blue dwarf galaxy UGC6456 (VII Zw 403). The source is highly variable in…
Ultraluminous X-ray sources with flat-topped noise and QPO
K. Atapin, S. Fabrika, M. D. Caballero-Garcia
We analyzed the X-ray power density spectra of five ultraluminous X-ray sources (ULXs) NGC5408 X-1, NGC6946 X-1, M82 X-1, NGC1313 X-1 and IC342 X-1 that are the only ULXs which dis…
Ultraluminous X-ray sources
Kirill Atapin
Ultraluminous X-ray sources (ULXs) represent a class of binary systems that are more luminous than any black hole in our Galaxy. The nature of these objects remained unclear for a…
X-ray Variability of SS 433: Evidence for Supercritical Accretion
Kirill Atapin, Sergei Fabrika
We study the X-ray variability of SS433 based on data from the ASCA observatory and the MAXI and RXTE/ASM monitoring missions. Based on the ASCA data, we have constructed the power…
Optical counterparts of two ultraluminous X-ray sources NGC4559 X-10 and NGC4395 ULX-1
A. Vinokurov, S. Fabrika, K. Atapin
We study the optical counterparts of ultraluminous X-ray sources NGC4559 X-10 and NGC4395 ULX-1. Their absolute magnitudes, after taking the reddening into account, are $M_V \appro…
Ultraluminous X-ray sources as super-Eddington accretion disks
Sergei Fabrika, Alexander Vinokurov, Kirill Atapin
The origin of Ultraluminous X-ray sources (ULXs) in external galaxies whose X-ray luminosities exceed those of the brightest black holes in our Galaxy by hundreds and thousands of…
Optical counterparts of two ULXs in NGC5474 and NGC3627 (M66)
S. Avdan, A. Vinokurov, S. Fabrika +6
We identified two optical counterparts of brightest ultraluminous X-ray Sources (ULXs) in galaxies NGC5474 and NGC3627 (M66). The counterparts in Hubble Space Telescope images are…
X-ray variability of SS433: effects of the supercritical accretion disc
Kirill Atapin, Sergei Fabrika, Aleksei Medvedev +1
We study a stochastic variability of SS433 in the Hz frequency range based on RXTE data, and on simultaneous observations with RXTE and optical telescop…
Ultra-luminous X-ray Sources as Supercritical Accretion Disks: Spectral Energy Distributions
A. Vinokurov, S. Fabrika, K. Atapin
We describe a model of spectral energy distribution in supercritical accretion disks (SCAD) based on the conception by Shakura and Sunyaev. We apply this model to five ultra-lumino…