arXiv subjects

M. N. Pavlinsky

Publications and source records attributed to M. N. Pavlinsky.

At least 19 recordsLinked to original sources

arXiv2024

SRG/ART-XC Galactic Plane Survey near Galactic Longitude $l\simeq20^\circ$: Catalog of Sources

We present a catalog of sources detected by the Mikhail Pavlinsky ART-XC telescope onboard the SRG space observatory during the observations of the Galactic plane region near a longitude $l\simeq20$ deg (L20 field) in October 2019. The L20 field was observed four times in the scanning mode, which provided a uniform coverage of the sky region with a total area of $\simeq24$ sq. deg with a median sensitivity of $8\times10^{-13}$ erg s$^{-1}$ cm$^{-2}$ (at 50% detection completeness) in the 4$-$12 keV. As a result, we have detected 29 X-ray sources at a statistically significant level, 11 of which have not been detected previously by other X-ray observatories. Preliminary estimates show that four of them can presumably be extragalactic in nature. We also show that the source SRGA J183220.1$-$103508 (CXOGSG J183220.8$-$103510), is most likely a galaxy cluster containing a bright radio galaxy at redshift $z\simeq0.121$.

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arXiv2020

Optical Identification of Four Hard X-ray Sources from the INTEGRAL Sky Surveys

We continue the study begun in Karasev et al. (2018) and present the results of our optical identifications of four hard X-ray sources from the INTEGRAL sky surveys. Having first improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory, we have identified their counterparts using optical and infrared sky survey data. Then, we have obtained optical spectra for the supposed counterparts with the RTT-150 Russian-Turkish telescope and the AZT-33IK telescope. This has allowed the nature of the objects under study to be established. The sources IGR J11079+7106 and IGR J12171+7047 have turned out to be extragalactic in nature and be Seyfert 1 and 2 galaxies, respectively, with the second object being characterized by a large absorption column density. The source IGR J18165-3912 is most likely an intermediate polar with a very high luminosity. The fourth source, IGR J20596+4303, is a chance superposition of two objects - a Seyfert 2 galaxy and a cataclysmic variable.

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arXiv2018

Optical Identification of X-ray Sources from the 14-Year INTEGRAL All-Sky Survey

We present the results of our optical identifications of several hard X-ray sources from the INTEGRAL all-sky survey obtained over 14 years of observations. Having improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory and the XMM-Newton observatory, we have identified their counterparts using optical and infrared sky survey data. We have obtained optical spectra for more than half of the objects from our sample with the RTT-150 and AZT-33IK telescopes, which have allowed us to establish the nature of the objects and to measure their redshifts. Six sources are shown to be extragalactic in origin and to belong to Seyfert 1 and 2 galaxies (IGR J01017+6519, IGR J08215-1320, IGR J08321-1808, IGR J16494-1740, IGR J17098-2344, IGR J17422-2108); we have failed to draw definitive conclusions about the nature of four more objects (IGR J11299-6557, IGR J14417-5533, IGR J18141-1823, IGR J18544+0839), but, judging by circumstantial evidence, they are most likely also extragalactic objects. For one more object (IGR J18044-1829) no unequivocal identification has been made.

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arXiv2017

Sample of Cataclysmic Variables from 400d X-ray Survey

We present a sample of cataclysmic variables (CVs) identified among the X-ray sources from the 400 square degree X-ray survey based on ROSAT pointing data (400d). The procedure of the CV selection among the X-ray sources using additional optical and infrared data from Sloan Digital Sky Survey and WISE survey is described. The results of the optical observations of the selected objects carried out mainly with the Russian-Turkish 1.5-m telescope (RTT-150) and the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (BTA) are presented. Some observations have also been performed with the Sayan Observatory 1.6-m AZT-33IK telescope. Currently we selected eight CVs, four of which were found for the first time in our work. Based on this sample, we have obtained preliminary constraints on the CV X-ray luminosity function in the solar neighborhood in the low luminosity range, L_X ~ 10^29-10^30 erg s^-1 (0.5-2 keV). We show that the logarithmic slope of the CV X-ray luminosity function in this luminosity range is less steep than at L_X > 10^31 erg s^-1. From our CV X-ray luminosity function estimates it follows that few thousand CVs will be detected in theSpectrum-Roentgen-Gamma (SRG) observatory all-sky X-ray survey at high Galactic latitudes, which will allow to obtain much more accurate measurements of CV X-ray luminosity function in the luminosity range L_X < 10^30-10^31 erg s^-1.

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arXiv2015

On the Possibility of Improving the Orbits of Satellites Based on Observations of Isolated X-ray Pulsars

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.

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arXiv2015

Determining the Nature of Faint X-Ray Sources from the ASCA Galactic Center Survey

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.

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arXiv2013

Identification of Four X-ray Sources from the INTEGRAL and Swift Catalogs

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.

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arXiv2012

On the Change of the Inner Boundary of an Optically Thick Accretion Disk around White Dwarfs Using the Dwarf Nova SS Cyg as an Example

We present the results of our studies of the aperiodic optical flux variability for SS Cyg, an accreting binary systemwith a white dwarf. The main set of observational data presented here was obtained with the ANDOR/iXon DU-888 photometer mounted on the RTT-150 telescope, which allowed a record(for CCD photometers) time resolution up to 8 ms to be achieved. The power spectra of the source's flux variability have revealed that the aperiodic variability contains information about the inner boundary of the optically thick flow in the binary system. We show that the inner boundary of the optically thick accretion disk comes close to the white dwarf surface at the maximum of the source's bolometric light curve, i.e., at the peak of the instantaneous accretion rate onto the white dwarf, while the optically thick accretion disk is truncated at distances 8.5e9 cm ~10 R_{WD} in the low state. We suggest that the location of the inner boundary of the accretion disk in the binary can be traced by studying the parameters of the power spectra for accreting white dwarfs. In particular, this allows the mass of the accreting object to be estimated.

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arXiv2011

Fast optical variability of SS 433

We study the optical variability of the peculiar Galactic source SS 433 using the observations made with the Russian Turkish 1.5-m telescope (RTT150). A simple technique which allows to obtain high-quality photometric measurements with 0.3-1 s time resolution using ordinary CCD is described in detail. Using the test observations of nonvariable stars, we show that the atmospheric turbulence introduces no significant distortions into the measured light curves. Therefore, the data obtained in this way are well suited for studying the aperiodic variability of various objects. The large amount of SS 433 optical light curve measurements obtained in this way allowed us to obtain the power spectra of its flux variability with a record sensitivity up to frequencies of ~0.5 Hz and to detect its break at frequency =~2.4e-3 Hz. We suggest that this break in the power spectrum results from the smoothing of the optical flux variability due to a finite size of the emitting region. Based on our measurement of the break frequency in the power spectrum, we estimated the size of the accretion-disk photosphere as 2e12 cm. We show that the amplitude of the variability in SS 433 decreases sharply during accretion-disk eclipses, but it does not disappear completely. This suggests that the size of the variable optical emission source is comparable to that of the normal star whose size is therefore R_O \approx 2e12 cm \approx 30 R_sun. The decrease in flux variability amplitude during eclipses suggests the presence of a nonvariable optical emission component with a magnitude m_R=~13.2.

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arXiv2010

Photometry and spectroscopy of GRB 060526: A detailed study of the afterglow and host galaxy of a z=3.2 gamma-ray burst

Aims: With this paper we want to investigate the highly variable afterglow light curve and environment of gamma-ray burst (GRB) 060526 at $z=3.221$. Methods: We present one of the largest photometric datasets ever obtained for a GRB afterglow, consisting of multi-color photometric data from the ultraviolet to the near infrared. The data set contains 412 data points in total to which we add additional data from the literature. Furthermore, we present low-resolution high signal-to-noise spectra of the afterglow. The afterglow light curve is modeled with both an analytical model using broken power law fits and with a broad-band numerical model which includes energy injections. The absorption lines detected in the spectra are used to derive column densities using a multi-ion single-component curve-of-growth analysis from which we derive the metallicity of the host of GRB 060526. Results: The temporal behaviour of the afterglow follows a double broken power law with breaks at $t=0.090\pm0.005$ and $t=2.401\pm0.061$ days. It shows deviations from the smooth set of power laws that can be modeled by additional energy injections from the central engine, although some significant microvariability remains. The broadband spectral-energy distribution of the afterglow shows no significant extinction along the line of sight. The metallicity derived from \ion{S}{II} and \ion{Fe}{II} of [S/H] = --0.57 $\pm$0.25 and [Fe/H] = --1.09$\pm$0.24 is relatively high for a galaxy at that redshift but comparable to the metallicity of other GRB hosts at similar redshifts. At the position of the afterglow, no host is detected to F775W(AB) = 28.5 mag with the HST, implying an absolute magnitude of the host M(1500 Å)$>$--18.3 mag which is fainter than most long-duration hosts, although the GRB may be associated with a faint galaxy at a distance of 11 kpc.

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arXiv2008

Optical Identifications of Five INTEGRAL Hard X-ray Sources in the Galactic Plane Region

The results of optical identifications of five hard X-ray sources in the Galactic plane region from the INTEGRAL all-sky survey are presented. The X-ray data on one source (IGRJ20216+4359) are published for the first time. The optical observations were performed with 1.5-m RTT-150 telescope (TUBITAK National Observatory, Antalya, Turkey) and 6-m BTA telescope (Special Astrophysical Observatory, Nizhny Arkhyz, Russia). A blazar, three Seyfert galaxies, and a high-mass X-ray binary are among the identified sources.

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arXiv2008

Several New Active Galactic Nuclei Among X-ray Sources Detected by INTEGRAL and SWIFT Observatories

We present the results of the optical identifications of a set of X-ray sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray sources were identified as active galactic nuclei (AGNs). Two of them are hosted by nearby, nearly exactly edge-on, spiral galaxies MCG -01-05-047 and NGC 973. One source, IGR J16562-3301, is most probably BL Lac object (blazar). Other AGNs are observed as stellar-like nuclei of spiral galaxies, with broad emission lines in their spectra. For the majority of our hard X-ray selected AGNs, their hard X-ray luminosities are well-correlated with the luminosities in [OIII],5007 optical emission line. However, the luminosities of some AGNs deviate from this correlation. The fraction of these objects can be as high as 20%. In particular, the flux in [OIII] line turns to be lower in two nearby edge-on spiral galaxies, which can be explained by the extinction in their galactic disks.

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arXiv2008

Observations of GRB 060526 Optical Afterglow with Russian-Turkish 1.5-m Telescope

We present the results of the photometric multicolor observations of GRB 060526 optical afterglow obtained with Russian-Turkish 1.5-m Telescope (RTT150, Mt. Bakirlitepe, Turkey). The detailed measurements of afterglow light curve, starting from about 5 hours after the GRB and during 5 consecutive nights were done. In addition, upper limits on the fast variability of the afterglow during the first night of observations were obtained and the history of afterglow color variations was measured in detail. In the time interval from 6 to 16 hours after the burst, there is a gradual flux decay, which can be described approximately as a power law with an index of -1.14+-0.02. After that the variability on the time scale δt < t is observed and the afterglow started to decay faster. The color of the afterglow, V-R=~0.5, is approximately the same during all our observations. The variability is detected on time scales up to δt/t =~ 0.0055 at ΔF_ν/F_ν=~ 0.3, which violates some constraints on the variability of the observed emission from ultrarelativistic jet obtained by Ioka et al. (2005). We suggest to explain this variability by the fact that the motion of the emitting shell is no longer ultrarelativistic at this time.

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arXiv2004

Broadband Observations of the Transient X-ray Pulsar SAX J2103.5+4545

We investigated the optical, X-ray, and gamma-ray variability of the pulsar SAX J2103.5+4545. Our timing and spectral analyses of the X-ray and gamma-ray emissions from the source using RXTE and INTEGRAL data show that the shape of its spectrum in the energy range 3 -- 100 keV is virtually independent of its intensity and the orbital phase. Based on XMM-Newton data, we accurately (5 arcsec) localized the object and determined the optical counterpart in the binary. We placed upper limits on the variability of the latter in the R band and the H-alpha line on time scales of the orbital and pulse periods, respectively.

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arXiv2004

Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror

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 radiation emitted in the past by the Sgr A* source. We conclude that 300-400 years ago Sgr A* was a low luminosity (L ~ 1.5e39 erg/s at 2-200 keV) AGN with a characteristic hard X-ray spectrum (photon index Gamma ~ 1.8). We estimate the mass and iron abundance of the Sgr B2 scattering gas at 2e6 Msun (r/10pc)^2 and 1.9 solar, respectively (where r is the radius of the cloud).

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arXiv2004

Two Years of Observations of the X-ray Pulsar SMC X-1 with the ART-P Telescope onboard the Granat Observatory

We present the observations of the pulsar SMC X-1 with the ART-P telescope onboard the Granat observatory. We investigate the variability of the flux from the source on time scales of several tens of days. The intensity variation of the pulsar are shown to be consistent with the presence of a periodicity in the system with a characteristic time scale of $\sim61$ days. The precession of an inclined accretion disk, as indirectly confirmed by the absence of low-state pulsations, may be responsible for the observed variability. The spectrum of the source is well described by a power-law energy dependence of the photon flux density with a slope of $\sim1.5$ and an exponential cutoff at energies above $\sim14-18$ keV. We estimated the inclinations between the planes of the orbit and the accretion disk and the magnetic field of the neutron star.

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arXiv2003

First hours of the GRB 030329 optical afterglow

We present the first results of the observations of the extremely bright optical afterglow of gamma-ray burst (GRB) 030329 with the 1.5m Russian-Turkish telescope RTT150 (TUBITAK National Observatory, Bakyrlytepe, Turkey). RTT150 was one of the first 1.5m-class telescopes pointed to the afterglow. Observations were started approximately 6 hours after the burst. During the first 5 hours of our observations the afterglow faded exactly as a power law with index -1.19+-0.01 in each of the BVRI Bessel filters. After that, in all BVRI filters simultaneously we observe a steepening of the power law light curve. The power law decay index smoothly approaches the value ~= -1.9, observed by other observatories later. This power law break occurs at t-t_0 =0.57 days and lasts for +-0.1 days. We observe no variability above the gradual fading with the upper limits 10--1% on time scales 0.1--1000s. Spectral flux distribution in four BVRI filters corresponds to the power law spectrum with spectral index α=0.66+-0.01. The change of the power law decay index in the end of our observations can be interpreted as a signature of collimated ultrarelativistic jet. The afterglow flux distribution in radio, optical and x-rays is consistent with synchrotron spectrum. We continue our observations of this unique object with RTT150.

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arXiv2002

Review of X-Ray Bursters in the Galactic Center Region

Results of observations of X-ray bursters in the Galactic Center region carried out with the RXTE observatory and the ART-P telescope on board GRANAT are presented. Eight X-ray bursters (A1742-294, SLX1744-299/300, GX3+1, GX354-0, SLX1732-304, 4U1724-307, KS1731-260) were revealed in this region during five series of observations which were performed with the ART-P telescope in 1990-1992 and more than 100 type I X-ray bursts from these sources were observed. For each of the sources we investigated in detail the recurrence times between bursts, the bursts time profiles and their dependence on the bursts flux, the spectral evolution of sources emission in the persistent state and during the bursts. Two bursters (SLX1732-304, 4U1724-307) located in the globular clusters Terzan 1 and 2, were investigated using the RXTE data as well.

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