A. Yu. Tkachenko

Masses and accretion rates of supermassive black holes in active galactic nuclei from the INTEGRAL survey

The masses of 68 supermassive black holes (SMBHs) in nearby (z < 0.15) active galactic nuclei (AGNs) detected by the INTEGRAL observatory in the hard X-ray energy band (17–60 keV) outside the Galactic plane (|b| 5°) have been estimated. Well-known relations between the SMBHmass and (1) the infrared luminosity of the stellar bulge (from 2MASS data) and (2) the characteristics of broad emission lines (from RTT-150 data) have been used. A comparison with the more accurate SMBH mass estimates obtained by the reverberation-mapping technique and from direct dynamical measurements is also made for several objects. The SMBH masses derived from the correlation with the bulge luminosity turn out to be systematically higher than the estimates made by other methods. The ratio of the bolometric luminosity to the critical Eddington luminosity has been found for all AGNs. It ranges from 1 to 100% for the overwhelming majority of objects.

Observational capabilities of the new medium- and low-resolution spectrograph at the 1.6-m telescope of the Sayan Observatory

The capabilities of the new medium- and low-resolution spectrograph installed recently on the 1.6-m AZT-33IK telescope at the Sayan Observatory of the Institute of Solar–Terrestrial Physics to solve the problems of ground-based optical support for the future all-skyX-ray survey of the SRGobservatory are discussed. Results of the test observations of galaxy clusters, active galactic nuclei (AGNs) and quasars, and cataclysmic variables performed immediately after the installation of the spectrograph on the telescope are presented. The results of these observations show that the AZT-33IK telescope equipped with the new medium- and low-resolution spectrograph can provide a substantial fraction of the necessary optical observations in the program of ground-based optical support for the all-sky survey of the SRG observatory.

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 8.5 × 109 cm ∼10RWD 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.

The first hours of the optical afterglow from the cosmic gamma-ray burst 030329

We describe the first results of our observations of the exceptionally bright optical afterglow from the cosmic gamma-ray burst (GRB) of March 29, 2003 (030329), with the 1.5-m Russian-Turkish telescope (RTT150) installed at the TUBITAK National Observatory (Turkey) at Mount Bakyrlytepe. RTT150 was one of the first medium-class telescopes pointed at the afterglow. The observations began as early as about six hours after the GRB. During the first five hours of our observations, the BV RI flux fell off exactly as a power law with the same slope −1.19±0.01. Subsequently, in all of the BV RI bands, we observed the same increase in the power-law slope of the light curve to a value that was later recorded during the observations at observatories in the western hemisphere. The break in the power-law light curve occurs at t − t0 ≈ 0.57 days (13.5 h) and lasts for about 0.2 days. Apart from this smooth decrease in the flux, the afterglow exhibited no flux variability. The upper limits on the variability are 10–1% on time scales of 0.1–1000 s, respectively. The BV RI spectral flux distribution during the first night of our observations closely corresponds to a power-law spectrum with a spectral index α=0.66±0.01. The change in the power-law slope of the light curve at the end of our observations is probably attributable to the deceleration of the ultrarelativistic jet to a gamma factor when its structural features begin to show up in the light curve. The radio, optical, and X-ray broadband spectrum is consistent with the assumption about the synchrotron radiation of the ultrarelativistic jet. This unique object continues to be observed with RTT150.We present the first results of the observations of the extrem ely bright optical afterglow of gamma-ray burst (GRB) 030329 with the 1.5m Russian-Turkish telescope RTT150 (T ¨ UBITAK National Observatory, Bakyrlytepe, Turkey). RTT150 was one of the first 1.5m-class telescopes pointed to the aftergl ow. Observations were started approximately 6 hours after the burst. During the first 5 hours of our observations the afterg low 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 − t0 ≈ 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 0.1‐1000 s. Spectral flux distribution in four BVRI filters corr esponds 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 coll imated ultrarelativistic jet. The afterglow flux distribut ion in radio, optical and x-rays is consistent with synchrotron sp ectrum. We continue our observations of this unique object with RTT150.

IGR J16547-1916/1RXS J165443.5-191620—a new intermediate polar from the INTEGRAL galactic survey

We present the results of our optical identification of the X-ray source IGR J16547-1916 detected by the INTEGRAL observatory during a deep all-sky survey. Analysis of the spectroscopic data from the SWIFT and INTEGRAL observatories in the X-ray energy band and from the BTA (Special Astrophysical Observatory) telescope in the optical band has shown that the source is most likely an intermediate polar—an accreting white dwarf with the mass ofMWD μ 0.85M⊙ binary system. Subsequent studies of the object’s rapid variability with the RTT-150 telescope have confirmed this conclusion by revealing periodic pulsations of its optical emission with a period of ≈550 s.

Additional spectroscopic redshift measurements for galaxy clusters from the first Planck catalogue

We present the results of spectroscopic redshift measurements for the galaxy clusters from the first all-sky Planck catalogue that have been mostly identified based on the optical observations performed previously by our team (Planck Collaboration 2015a). Data on 13 galaxy clusters at redshifts from z ≈ 0.2 to z ≈ 0.8, including the improved identification and redshift measurement for the cluster PSZ1 G141.73+14.22 at z = 0.828, are provided. We have performed the measurements based on data from the Russian–Turkish 1.5-m telescope (RTT-150), the 2.2-m Calar Alto Observatory telescope, and the 6-m SAO RAS telescope (Bolshoy Teleskop Azimutalnyi, BTA).

Sample of cataclysmic variables detected in the 400d X-ray survey

A sample of cataclysmic variables (CVs) detected among the X-ray sources of the 400 square degree (400d) survey performed based on ROSAT pointings is presented. A technique for selecting CVs among the X-ray sources using additional optical and infrared data, based on Sloan Digital Sky Survey andWISE data, is described. We present 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). Some observations have also been performed with the 1.6-m AZT-33IK telescope of the Institute of Solar–Terrestrial Physics, the Siberian branch of the Russian Academy of Sciences. Eight CVs, four of which were detected in our work, have been selected by now. Based on this sample, we have obtained preliminary constraints on the X-ray luminosity function of CVs in the solar neighborhood in the range of low luminosities, LX ~ 1029–1030 erg s−1 (0.5–2 keV). The logarithmic slope of the CV luminosity function in this luminosity range is shown to become gentler than that at LX > 1031 erg s−1. It follows from our estimates of the CV luminosity function that several thousand CVs will be detected in the SRG all-sky survey at high Galactic latitudes, which will allow much more accurate measurements of their X-ray luminosity function to be obtained.

Search for cataclysmic variables based on the 400d X-ray sky survey

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.

New cataclysmic variable 1RXS J073346.0+261933 in Gemini

In the course of our search for the optical identifications of ROSAT X-ray sources, we have found a highly variable object with a very unusual behavior on long time scales, rare color indices, and a high X-ray-to-optical flux ratio. We present the archival light curve from the Catalina Sky Survey, optical spectroscopy from RTT150, and time-resolved photometry from the Astrotel-Caucasus telescope. The object appears to be a magnetic cataclysmic variable (a polar) with an orbital period P = 3.20 h.

The Influence of the Thermal Conditions of a Grazing-Incidence Mirror on Its Characteristics

This article presents the findings of experimental research on the thermal conditions of the grazing-incidence mirrors used in the first Russian X-ray mirror telescope and theoretical studies of the influence of the temperature gradients on the characteristics of the X-ray mirrors.