M. Revnivtsev

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (274)571.93 Total impact

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    ABSTRACT: At present, there is a great worldwide interest in the development of technologies that allow information about the X-ray emission from pulsating cosmic sources to be used to obtain navigation solutions for deep-space spacecraft. In this paper, we illustrate the technique for determining the spatial position of a spacecraft based on the already existing data from the RXTE X-ray space observatory. We show that the spacecraft position toward the Crab pulsar can be determined using an X-ray detector with an effective area of about 0.6 sq.m in the energy range 3-15 keV with an accuracy up to 730 m in a signal integration time of 1000 s. Extending the energy range to 1 keV (the efficiency of the RXTE/PCA spectrometer decreases dramatically at energies below 3 keV) will allow a spacecraft position accuracy of 400-450 m to be achieved at the same effective area and up to 300-350 m when using detectors with an effective area of ~1 sq.m in the energy range 1-10 keV.
    Astronomy Letters 07/2015; 41(8). DOI:10.1134/S106377371508006X · 1.30 Impact Factor
  • Mikhail G. Revnivtsev · Sergey V. Molkov · Mikhail N. Pavlinsky
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    ABSTRACT: We report results of our search for fast oscillations in lightcurve of one of the brightest accretion powered pulsars on the sky V0332+53 with the help of data of the PCA spectrometer of the RXTE observatory. In course of this search we have carefully explored complications appearing if one uses only sub-bands of the total bandpass of the PCA spectrometer. We show that lightcurves collected in the soft sub-band of the PCA spectrometer contains an additional instrumental noise, lightcurves of harder sub-bands lack some fraction of the anticipated Poisson noise. We show that this noise is caused by a cross-talk of energy bands, which lasts up to ~200usec. One hypothesis is that these effects are caused by temporarily drop of the PCA detector gain after any occurred event due to slowly moving ions in the detector volume. In order to avoid this effect we searched for fast oscillations in flux of V0332+53 only in the total bandpass of the PCA spectrometer 2-60 keV. We have not detected any quasi-periodic oscillations in lightcurve of the source with an upper limit at the level of 0.5% in the Fourier frequency range 200-1500 Hz.
    Monthly Notices of the Royal Astronomical Society 06/2015; 451(4). DOI:10.1093/mnras/stv1263 · 5.23 Impact Factor
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    ABSTRACT: We present the first results of our search for cataclysmic variables among the point X-ray sources detected in a part of the sky survey with an area of 400 sq. deg. performed on the basis of data from the ROSAT telescope (400d), for which photometric data from the Sloan Digital Sky Survey are also available. The necessary optical observations of the candidates for cataclysmic variables have been carried out with the 1.5-m Russian-Turkish telescope (RTT-150). We show that one of the four investigated objects (400D J0019126+220733) is a cataclysmic variable, two objects are quasars at redshifts z ∼ 2, and the nature of one object remains unclarified; however, we can exclude it from the list of possible candidates for cataclysmic variables: its spectrum contains no characteristic emission features.
    Astronomy Letters 05/2015; 41(5):174-178. DOI:10.1134/S1063773715050084 · 1.30 Impact Factor
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    ABSTRACT: We present the results of the identification of six objects from the ASCA Galactic center and Galactic plane surveys: AXJ173548-3207, AXJ173628-3141, AXJ1739.5-2910, AXJ1740.4-2856, AXJ1740.5-2937, AXJ1743.9-2846. Chandra, XMM-Newton, and XRT/Swift X-ray data have been used to improve the positions of the optical counterparts to these sources. Thereafter, we have carried out a series of spectroscopic observations of the established optical counterparts at the RTT-150 telescope. Analysis of X-ray and optical spectra as well as photometric measurements in a wide wavelength range based on optical and infrared catalogs has allowed the nature of the program sources to be determined. Two X-ray objects have been detected in the error circle of AXJ173628-3141: one is a coronally active G star and the other may be a symbiotic star, a red giant with an accreting white dwarf. Three sources (AXJ1739.5-2910, AXJ1740.5-2937, AXJ1743.9-2846) have turned out to be active G-K stars, presumably RS CVn objects, one (AXJ1740.4-2856) is an M dwarf, and another one (AXJ173548-3207) may be a low-mass X-ray binary in its low state. The distances and corresponding luminosities of the sources in the soft X-ray band have been estimated; analysis of deep INTEGRAL Galactic Center observations has not revealed a statistically significant flux at energies higher 20 keV from any of them.
    Astronomy Letters 04/2015; 41(5). DOI:10.1134/S1063773715050060 · 1.30 Impact Factor
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    ABSTRACT: We present the results of an all-sky survey, performed with data acquired by the Imager on-Board the INTEGRAL Satellite (IBIS) telescope on board the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observatory over 11 years of operation, at energies above 100 keV. The catalogue of detected sources includes 132 objects. The statistical sample detected on the time-averaged 100–150 keV map at a significance above 5σ contains 88 sources: 28 active galactic nuclei (AGNs), 38 low-mass X-ray binaries (LMXBs), 10 high-mass X-ray binaries (HMXBs) and 12 rotation-powered young X-ray pulsars. The catalogue also includes 15 persistent sources, which were registered at significance 4σ ≤ S/N < 5σ, where S/N is the signal-to-noise ratio, but at the same time were firmly detected (≥12σ) in the lower 17–60 keV energy band. All registered sources are known X-ray emitters, which means that the catalogue has 100 per cent purity in this respect. Additionally, 29 catalogued sources were detected significantly in different time slices of the survey. In the context of the survey, we present a hardness ratio for Galactic and extragalactic sources, an LMXB longitudinal asymmetry and a number–flux relation for non-blazar AGNs. At higher energies, in the 150–300 keV energy band, 25 sources have been detected with S/N ≥ 5σ, including seven AGNs, 13 LMXBs, three HMXBs and two rotation-powered pulsars. Among LMXBs and HMXBs, we identified 12 black hole candidates (BHCs) and four neutron star (NS) binaries.
    Monthly Notices of the Royal Astronomical Society 12/2014; 448(4). DOI:10.1093/mnras/stv150 · 5.23 Impact Factor
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    Mikhail Revnivtsev · Sandro Mereghetti
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    ABSTRACT: A substantial fraction of the known neutron stars resides in X-ray binaries -- systems in which one compact object accretes matter from a companion star. Neutron stars in X-ray binaries have magnetic fields among the highest found in the Universe, spanning at least the range from $\sim10^8$ to several 10$^{13}$ G. The magnetospheres around these neutron stars have a strong influence on the accretion process, which powers most of their emission. The magnetic field intensity and geometry, are among the main factors responsible for the large variety of spectral and timing properties observed in the X-ray energy range, making these objects unique laboratories to study the matter behavior and the radiation processes in magnetic fields unaccessible on Earth. In this paper we review the main observational aspects related to the presence of magnetic fields in neutron star X-ray binaries and some methods that are used to estimate their strength.
    Space Science Reviews 11/2014; DOI:10.1007/s11214-014-0123-x · 5.87 Impact Factor
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    Ivan Yu Zolotukhin · Mikhail G. Revnivtsev
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    ABSTRACT: We report on archival near-infrared and mid-infrared observations of seven persistent X-ray sources situated in the Galactic bulge, using data from the UK Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS), the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) and the Wide-field Infrared Survey Explorer (WISE) all-sky survey. We were able to successfully identify or provide upper flux limits for the systems SAX J1747.0−2853, IGR J17464−2811, AX J1754.2−2754, IGR J17597−2201, IGR J18134−1636, IGR J18256−1035 and Ser X−1 and constrain the nature of these systems. In the case of IGR J17597−2201, we present arguments that the source accretes matter from the stellar wind rather than via Roche-lobe overflow of the secondary. We suggest that, at its X-ray luminosity of 1034 − 35 erg s−1, we are probing the poorly known class of wind-fed low-mass X-ray binaries (LMXBs).
    Monthly Notices of the Royal Astronomical Society 10/2014; 446(3). DOI:10.1093/mnras/stu2212 · 5.23 Impact Factor
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    M. G. Revnivtsev
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    ABSTRACT: The paper describes previous studies of the cosmic X-ray background (CXB) of the Universe in the energy range 1-100 keV and outline prospects for its investigation with the help of 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 paper is devoted to the methods of CXB measurements, from the first pioneering rocket and balloon-borne experiments to the measurements made with latest-generation orbital X-ray observatories. Particular attention is given to the problems of allowance for the contribution of background events to the measurements with X-ray and hard X-ray instruments.
    Astronomy Letters 10/2014; 40(11). DOI:10.1134/S106377371411005X · 1.30 Impact Factor
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    ABSTRACT: We study hard X-ray emission of the brightest accreting neutron star Sco X-1 with INTEGRAL observatory. Up to now INTEGRAL have collected ∼4 Ms of deadtime corrected exposure on this source. We show that hard X-ray tail in time average spectrum of Sco X-1 has a power-law shape without cutoff up to energies ∼200–300 keV. An absence of the high energy cutoff does not agree with the predictions of a model, in which the tail is formed as a result of Comptonization of soft seed photons on bulk motion of matter near the compact object. The amplitude of the tail varies with time with factor more than 10 with the faintest tail at the top of the so-called flaring branch of its colour–colour diagram. We show that the minimal amplitude of the power-law tail is recorded when the component, corresponding to the innermost part of optically thick accretion disc, disappears from the emission spectrum. Therefore, we show that the presence of the hard X-ray tail may be related with the existence of the inner part of the optically thick disc. We estimate cooling time for these energetic electrons and show that they cannot be thermal. We propose that the hard X-ray tail emission originates as a Compton upscattering of soft seed photons on electrons, which might have initial non-thermal distribution.
    Monthly Notices of the Royal Astronomical Society 09/2014; 445(2). DOI:10.1093/mnras/stu1831 · 5.23 Impact Factor
  • A. N. Semena · M. G. Revnivtsev
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    ABSTRACT: The goal of this paper is to determine the characteristic cooling time of the accretion flowmatter near the surface of the magnetic white dwarf in the binary system EX Hya. Most of the X-ray photons in such binary systems are produced in an optically thin hot plasma with a temperature above 10 keV heated when the matter passes through the shock near the white dwarf surface. The total X-ray luminosity is determined by the matter accumulated below the shock in its cooling time. Thus, the X-ray luminosity variability related to the variations in the accretion rate onto the white dwarf surface must be suppressed at frequencies higher than the inverse cooling time. If the optically thin plasma radiation dominates in the rate of energy losses by the heated matter, which is true for white dwarfs with moderately strong magnetic fields, less than 1–10 MG, then the matter cooling time can give an estimate of the matter density in the accretion column. Given the accretion rate and the matter density in the accretion column at the white dwarf surface, the area of the accretion channel can be estimated. We have analyzed all of the currently available observational data for one of the brightest intermediate polars in the X-ray sky, EX Hya, from the RXTE and XMM-Newton observatories. The power spectra of its aperiodic variability have given an upper limit on the cooling time of the hot plasma: <1.5–2 s. For the observed accretion rate, ×1015 g s−1, this corresponds to a matter density below the shock surface ≳1016 cm−3 and an area of the base of the accretion channel no more than <4.6 × 1015 cm2. Using the information about the maximum geometrical size of the accretion channel obtained by analyzing X-ray eclipses in the binary system EX Hya, we have derived an upper limit on the thickness of the flow over the surface of the magnetosphere near the white dwarf surface, ≲3 × 106 cm, and the plasma penetration depth at the magnetospheric boundary, Δr/r ≲ 6 × 10−3.
    Astronomy Letters 08/2014; 40(8):475-484. DOI:10.1134/S1063773714080088 · 1.30 Impact Factor
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    ABSTRACT: Neutron star (NS) masses and radii can be estimated from observations of photospheric radius-expansion X-ray bursts, provided the chemical composition of the photosphere, the spectral colour-correction factors in the observed luminosity range, and the emission area during the bursts are known. By analysing 246 X-ray bursts observed by the Rossi X-ray Timing Explorer from 11 low-mass X-ray binaries, we find a dependence between the persistent spectral properties and the time evolution of the blackbody normalization during the bursts. All NS atmosphere models predict that the colour-correction factor decreases in the early cooling phase when the luminosity first drops below the limiting Eddington value, leading to a characteristic pattern of variability in the measured blackbody normalization. However, the model predictions agree with the observations for most bursts occurring in hard, low-luminosity, island spectral states, but rarely during soft, high-luminosity, banana states. The observed behaviour may be attributed to the accretion flow, which influences cooling of the NS preferentially during the soft state bursts. This result implies that only the bursts occurring in the hard, low-luminosity spectral states can be reliably used for NS mass and radius determination.
    Monthly Notices of the Royal Astronomical Society 06/2014; 445(4). DOI:10.1093/mnras/stu2073 · 5.23 Impact Factor
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    ABSTRACT: We present results of a study of the fast timing variability of the magnetic cataclysmic variable (mCV) EX Hya. It was previously shown that one may expect the rapid flux variability of mCVs to be smeared out at timescales shorter than the cooling time of hot plasma in the post shock region of the accretion curtain near the WD surface. Estimates of the cooling time and the mass accretion rate, thus provide us with a tool to measure the density of the post-shock plasma and the cross-sectional area of the accretion funnel at the WD surface. We have probed the high frequencies in the aperiodic noise of one of the brightest mCV EX Hya with the help of optical telescopes, namely SALT and the SAAO 1.9m telescope. We place upper limits on the plasma cooling timescale $\tau<$0.3 sec, on the fractional area of the accretion curtain footprint $f<1.6\times10^{-4}$, and a lower limit on the specific mass accretion rate $\dot{M}/A \gtrsim $3 g/sec/cm$^{-2}$. We show that measurements of accretion column footprints via eclipse mapping highly overestimate their areas. We deduce a value of $\Delta r/r \lesssim 10^{-3}$ as an upper limit to the penetration depth of the accretion disc plasma at the boundary of the magnetosphere.
    Monthly Notices of the Royal Astronomical Society 05/2014; 442(2). DOI:10.1093/mnras/stu897 · 5.23 Impact Factor
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    M. G. Revnivtsev · E. V. Filippova · V. F. Suleimanov
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    ABSTRACT: 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 optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brightness does not drop below Mg~13-14. Using the latter fact, we show that in current and planned X-ray sky surveys, the family of accreting nonmagnetic white dwarfs can be completely identified to the distance determined by the sensitivity of an optical sky survey in this region. For the Sloan Digital Sky Survey (SDSS) with a limiting sensitivity m_g~22.5, this distance is ~400-600 pc
    Astronomy Letters 04/2014; 40(4). DOI:10.1134/S1063773714040057 · 1.30 Impact Factor
  • A. G. Kuranov · K. A. Postnov · M. G. Revnivtsev
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    ABSTRACT: The evolution of the family of binaries with a low-mass star and a compact neutron star companion (low-mass X-ray binaries (LMXBs) with neutron stars) ismodeled by the method of population synthesis. Continuous Roche-lobe filling by the optical star in LMXBs is assumed to be maintained by the removal of orbital angular momentum from the binary by a magnetic stellar wind from the optical star and the radiation of gravitational waves by the binary. The developed model of LMXB evolution has the following significant distinctions: (1) allowance for the effect of the rotational evolution of a magnetized compact remnant on themass transfer scenario in the binary, (2) amore accurate allowance for the response of the donor star to mass loss at the Roche-lobe filling stage. The results of theoretical calculations are shown to be in good agreement with the observed orbital period-X-ray luminosity diagrams for persistent Galactic LMXBs and their X-ray luminosity function. This suggests that the main elements of binary evolution, on the whole, are correctly reflected in the developed code. It is shown that most of the Galactic bulge LMXBs at luminosities L x > 1037 erg s-1 should have a post-main-sequence Roche-lobe-filling secondary component (low-mass giants). Almost all of the models considered predict a deficit of LMXBs at X-ray luminosities near ̃1036.5 erg s-1 due to the transition of the binary from the regime of angular momentum removal by a magnetic stellar wind to the regime of gravitational waves (analogous to the widely known period gap in cataclysmic variables, accreting white dwarfs). At low luminosities, the shape of the model luminosity function for LMXBs is affected significantly by their transient behavior-the accretion rate onto the compact companion is not always equal to the mass transfer rate due to instabilities in the accretion disk around the compact object. The best agreement with observed binaries is achieved in the models suggesting that heavy neutron stars with masses 1.4-1.9 M ☉ can be born.
    Astronomy Letters 12/2013; 40(1). DOI:10.1134/S1063773714010034 · 1.30 Impact Factor
  • E. Filippova · M. Revnivtsev · E. R. Parkin
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    ABSTRACT: We consider modulations of mass captured by the compact object from the companion star's stellar wind in Low Mass X-ray Binaries with late type giants. Based on 3D simulations with two different hydrodynamic codes used Lagrangian and Eulerian approaches - the SPH code GADGET and the Eulerian code PLUTO, we conclude that a hydrodynamical interaction of the wind matter within a binary system even without eccentricity results in variability of the mass accretion rate with characteristic time-scales close to the orbital period. Observational appearances of this wind might be similar to that of an accretion disc corona/wind.
    The European Physical Journal Conferences 12/2013; 64. DOI:10.1051/epjconf/20136402008
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    ABSTRACT: 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 optically thick and optically thin regimes. The galaxy's luminosity at energies 20-100 keV gives about 6% of its total luminosity in the 3-100 keV band. The emissivity of the stellar population in M31 is L 2-20 keV ̃ 1.1 × 1029 erg s-1 M {☉/-1} in the 2-20 keV band and L 20-100 keV ̃ 8 × 1027 erg s-1 M {☉/-1} in the 20-100 keV band. Since low-mass X-ray binaries at high luminosities pass into a soft state with a small fraction of hard X-ray emission, the detection of individual hard X-ray sources in M31 requires a sensitivity that is tens of times better (up to 10-13 erg s-1 cm-2) than is needed to detect the total hard X-ray emission from the entire galaxy. Allowance for the contribution from the hard spectral component of the galaxy changes the galaxy's effective Compton temperature approximately by a factor of 2, from ̃1.1 to ̃2.1 keV.
    Astronomy Letters 12/2013; 40(1). DOI:10.1134/S1063773714010046 · 1.30 Impact Factor
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    E. Filippova · M. Revnivtsev · E. R. Parkin
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    ABSTRACT: In this paper we propose and examine a physical mechanism which can lead to the generation of noise in the mass accretion rate of low mass X-ray binaries on time-scales comparable to the orbital period of the system. We consider modulations of mass captured by the compact object from the companion star's stellar wind in binaries with late type giants, systems which usually have long orbital periods. We show that a hydrodynamical interaction of the wind matter within a binary system even without eccentricity results in variability of the mass accretion rate with characteristic time-scales close to the orbital period. The cause of the variability is an undeveloped turbulent motion (perturbed motion without significant vorticity) of wind matter near the compact object. Our conclusions are supported by 3D simulations with two different hydrodynamic codes based on Lagrangian and Eulerian approaches -- the SPH code GADGET and the Eulerian code PLUTO. In this work we assume that the wind mass loss rate of the secondary is at the level of $(0.5-1)\times10^{-7} M_\odot$/year, required to produce observable variations of the mass accretion rate on the primary. This value is higher than that, estimated for single giant stars of this type, but examples of even higher mass loss rate of late type giants in binaries do exist. Our simulations show that the stellar wind matter intercepted by the compact object might create observational appearances similar to that of an accretion disc corona/wind and could be detected via high energy resolution observations of X-ray absorption lines, in particular, highly ionized ions of heavy elements.
    Monthly Notices of the Royal Astronomical Society 10/2013; 437(1). DOI:10.1093/mnras/stt1870 · 5.23 Impact Factor
  • M. G. Revnivtsev · A. Kniazev · D. I. Karasev · L. Berdnikov · S. Barway
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    ABSTRACT: Increasing the identification completeness of sources from new X-ray sky surveys is a necessary condition for further works on analyzing the formation and long-term evolution of star systems in our Galaxy. Infrared observations of several sources selected from Galactic plane surveys as candidates for low-mass X-ray binaries with the IRSF telescope at the South African Astronomical Observatory are presented. The infrared fluxes have been reliably measured from five of the eight sources (4U 1556-60, 4U 1708-40, AX J165901-4208, IGR J16287-5021, IGR J17350-2045, AX J171922-3703, SAX J1712.6-3739, 4U 1705-32). One of the objects (AX J165901-4208) may be a candidate for symbiotic X-ray binaries, i.e., binaries in which the companion of a relativistic object is a giant star. The distances have been estimated for three sources and the orbital periods have been estimated for two.
    Astronomy Letters 08/2013; 39(8):523-531. DOI:10.1134/S1063773713080082 · 1.30 Impact Factor
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    ABSTRACT: Four hard X-ray sources from the INTEGRAL and Swift catalogs have been identified. X-ray and optical spectra have been obtained for each of the objects being studied by using data from the INTEGRAL, Swift, ROSAT, and Chandra X-ray observatories as well as observations with the RTT-150 and AZT-33IK optical telescopes. Two sources (SWIFT J1553.6+2606 and SWIFT J1852.2+8424) are shown to be extragalactic in nature: the first is a quasar, while the registered X-ray flux from the second is the total emission from two Seyfert 1 galaxies at redshifts 0.1828 and 0.2249. The source IGR J22534+6243 resides in our Galaxy and is an X-ray pulsar with a period of ~46.674 s that is a member of a high-mass X-ray binary, probably with a Be star. The nature of yet another Galactic source, SWIFT J1852.8+3002, is not completely clear and infrared spectroscopy is needed to establish it.
    Astronomy Letters 07/2013; 39(8). DOI:10.1134/S1063773713080069 · 1.30 Impact Factor
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    Mikhail G. Revnivtsev · Valery F. Suleimanov · Juri Poutanen
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    ABSTRACT: Emission of the neutron star surface potentially contains information about its size and thus of vital importance for high energy astrophysics. In spite of the wealth of data on the emission of luminous accreting neutron stars, the emission of their surfaces is hard to disentangle from their time averaged spectra. A recent X-ray transient source XTE J1701-462 has provided a unique dataset covering the largest ever observed luminosity range for a single source. In this paper, we extract the spectrum of the boundary layer between the inner part of the accretion disc and the neutron star surface with the help of maximally spectral model-independent method. We show compelling evidences that the energy spectrum of the boundary layer stays virtually the same over factor of 20 variations of the source luminosity. It is rather wide and cannot be described by a single temperature blackbody spectrum, probably because of the inhomogeneity of the boundary layer and a spread in the colour temperature. The observed maximum colour temperature of the boundary/spreading layer emission of kT~2.4-2.6 keV is very close to the maximum observed colour temperature in the photospheric radius expansion X-ray bursts, which is set by the limiting Eddington flux at the neutron star surface. Observed stability of the boundary layer spectrum and its maximum colour temperature strongly supports theoretical models of the boundary/spreading layers on surfaces of luminous accreting neutron stars, which assume the presence of a region emitting at the local Eddington limit. Variations in the luminosity in that case lead to changes in the size of this region, but affect less the spectral shape. Elaboration of this model will provide solid theoretical grounds for measurements of the neutron star sizes using the emission of the boundary/spreading layers of luminous accreting neutron stars.
    Monthly Notices of the Royal Astronomical Society 06/2013; 434(3). DOI:10.1093/mnras/stt1179 · 5.23 Impact Factor

Publication Stats

3k Citations
571.93 Total Impact Points

Institutions

  • 1998–2014
    • Russian Academy of Sciences
      • Space Research Institute
      Moskva, Moscow, Russia
  • 1997–2014
    • Space Research Institute
      Moskva, Moscow, Russia
  • 2008–2010
    • Technische Universität München
      München, Bavaria, Germany
  • 2005–2010
    • Harvard-Smithsonian Center for Astrophysics
      • Smithsonian Astrophysical Observatory
      Cambridge, Massachusetts, United States
  • 2006
    • University of California, Riverside
      Riverside, California, United States
  • 2004–2006
    • Max Planck Institute for Astrophysics
      Arching, Bavaria, Germany
    • NASA
      Вашингтон, West Virginia, United States
    • Akdeniz University
      • Department of Physics
      Satalia, Antalya, Turkey