Ilfan Bikmaev

INTEGRAL observations of SS433: Results of a coordinated campaign

Results of simultaneous INTEGRAL and optical observations of the galactic microquasar SS433 in May 2003 and INTEGRAL /RXTE observations in March 2004 are presented. Persistent precessional variability with a maximum to minimum uneclipsed hard X-ray flux ratio of ∼ 4 is discovered. The 18-60 keV X-ray eclipse is found to be in phase with optical and near infrared eclipses. The orbital eclipse observed by INTEGRAL in May 2003 is at least two times deeper and apparently wider than in the soft X-ray band. The broadband 2-100 keV X-ray spectrum simultaneously detected by RXTE/INTEGRAL in March 2004 can be explained by bremsstrahlung emission from optically thin thermal plasma with kT ∼ 30 keV. Optical spectroscopy with the 6-m SAO BTA telescope confirmed the optical companion to be an A5-A7 supergiant. For the first time, spectorscopic indications of a strong heating effect in the optical star atmosphere are found. The measurements of absorption lines which are presumably formed on the non-illuminated side of the supergiant yield its radial velocity semi-amplitude Kv = 132 ±9 km/s. The analysis of the observed hard X-ray light curve and the eclipse duration, combined with the spectroscopically determined optical star radial velocity corrected for the strong heating effect, allows us to model SS433 as a massive X-ray binary. Assuming that the hard X-ray source in SS433 is eclipsed by the donor star that exactly fills its Roche lobe, the masses of the optical and compact components in SS433 are suggested to be Mv ≈ 30M⊙ and Mx ≈ 9M⊙, respectively. This provides further evidence that SS433 is a massive binary system with supercritical accretion onto a black hole.

Around-the-Clock Observations of the Q0957+561A,B Gravitationally Lensed Quasar. II. Results for the Second Observing Season

We report on an observing campaign in 2001 March to monitor the brightness of the later arriving Q0957+561B image in order to compare with the previously published brightness observations of the (first-arriving) A image. The 12 participating observatories provided 3543 image frames, which we have analyzed for brightness fluctuations. From our classical methods for time-delay determination, we find a 417.09 ± 0.07 day time delay, which should be free of effects due to incomplete sampling. During the campaign period, the quasar brightness was relatively constant and only small fluctuations were found; we compare the structure function for the new data with structure function estimates for the 1995-1996 epoch and show that the structure function during our observing interval is unusually depressed. We also examine the data for any evidence of correlated fluctuations at zero lag. We discuss the limits of our ability to measure the cosmological time delay if the quasars emitting surface is time resolved, as seems likely.

Gamma Rays from Type Ia Supernova SN 2014J

The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 16-162 days after the explosion has being analyzed. For spectral fitting the data are split into early and late periods covering days 16-35 and 50-162, respectively, optimized for Ni and Co lines. As expected for the early period much of the gamma-ray signal is confined to energies below ∼200 keV, while for the late period it is most strong above 400 keV. In particular, in the late period Co lines at 847 and 1248 keV are detected at 4.7 and 4.3 σ respectively. The lightcurves in several representative energy bands are calculated for the entire period. The resulting spectra and lightcurves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical 1D models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass WD. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe lines profiles, suggesting that unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.The whole set of INTEGRAL observations of Type Ia supernova SN 2014J, covering the period 19–162 days after the explosion, has been analyzed. For spectral fitting the data are split into early and late periods covering days 19–35 and 50–162, respectively, optimized for 56 Ni and 56 Co lines. As expected for the early period, much of the gamma-ray signal is confined to energies below ∼200 keV, while for the late period it is strongest above 400 keV. In particular, in the late period, 56 Co lines at 847 and 1248 keV are detected at 4.7σ and 4.3σ, respectively. The light curves in several representative energy bands are calculated for the entire period. The resulting spectra and light curves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical one-dimensional models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass white dwarf. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe line profiles, suggesting that, unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.

Optical identifications of five INTEGRAL hard X-ray sources in the Galactic plane

The results of optical identifications of five hard X-ray sources in the Galactic plane from the INTEGRAL all-sky survey are presented. The X-ray data on one source (IGR J20216+4359) are published for the first time. The optical observations were performed with the 1.5-m RTT-150 telescope (Turkish National Observatory, Antalya, Turkey) and the 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.

The new pre-cataclysmic binary PG 2200+085

Aims. We present the results of spectroscopic- and orbit-sampled photometric observations of the faint UV-excess object PG 2200+085. Methods. The optical CCD photometry observations of this object were performed by the Russian-Turkish 1.5-m telescope RTT150 at the TUBITAK National Observatory (Turkey). The long-slit optical spectroscopy observations with 2.6 A resolution were carried out by 6-m telescope BTA at the Special Astrophysical Observatory (Russia). Results. The photometric variations over two nights are almost sinusoidal with an amplitude ∆mV = 0. m 04 and a period of P = 0.3186 d. Such a light curve is typical of a detached close binary with an illumination effect or the ellipsoidal deformation of a secondary star. The observed spectrum clearly displays a featureless blue continuum of a hot component and a rich absorption-line and molecular band K-star spectrum. The CaII line profiles with strong emission cores are remarkably similar to those of V471 Tau. Conclusions. We tentatively classify PG 2200+085 as a pre-cataclysmic binary of the V471 Tau type.

Cyclic brightening in the short-period WZ Sge-type cataclysmic variable SDSS J080434.20+510349.2

Aims. We observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 to study the origin of long-term variability found in its light curve. Methods. Multi-longitude, time-resolved, photometric observations were acquired to analyze this uncommon behavior, which has been found in two newly discovered CVs. Results. This study of SDSS J080434.20+510349.2 concerns primarily the understanding of the nature of the observed, doublehumped, light curve and its relation to a cyclic brightening that occurs during quiescence. The observations were obtained early in 2007, when the object was at about V ∼ 17.1, about 0.4 mag brighter than the pre-outburst magnitude. The light curve shows a sinusoidal variability with an amplitude of about 0.07 mag and a periodicity of 42.48 min, which is half of the orbital period of the system. We observed in addition two “mini-outbursts” of the system of up to 0.6 mag, which have a duration of about 4 days each. The “mini-outburst” has a symmetric profile and is repeated in approximately every 32 days. Subsequent monitoring of the system shows a cyclical behavior of such “mini-outbursts” with a similar recurrence period. The origin of the double-humped light curve and the periodic brightening is discussed in the light of the evolutionary state of SDSS J080434.20+510349.2.

New nearby active galactic nuclei among INTEGRAL and RXTE X-ray sources

We present the first results of a campaign to optically identify X-ray sources discovered in the all-sky surveys of the RXTE and INTEGRAL observatories. Six newly discovered sources proved to be hitherto unknown nearby active galactic nuclei (z < 0.1). Spectrophotometric studies of these sources were performed with the Russian-Turkish 1.5-m telescope (RTT150). We measured their redshifts and parameters of the strongest emission lines.We present first results of a campaign of optical identifications of X-ray sources discovered by RXTE and INTEGRAL observatories during their sky surveys. In this work we study six newly discovered nearby active galactic nuclei at z<0.1. The optical spectrophotometric data were obtained with Russian-Turkish 1.5-m telescope (RTT150). We present their redshifts and main parameters of brightest emission lines.

Extensive multiband study of the X-ray rich GRB 050408: a likely off-axis event with an intense energy injection

Aims. Understand the shape and implications of the multiband ligth curve of GRB 050408, an X-ray rich (XRR) burst. Methods. We present a multiband optical light curve, covering the time from the onset of the γ-ray event to several months after, when we only detect the host galaxy. Together with X-ray, millimetre and radio observations we compile what, to our knowledge, is the most complete multiband coverage of an XRR burst afterglow to date. Results. The optical and X-ray light curve is characterised by an early flattening and an intense bump peaking around 6 days after the burst onset. We explain the former by an off-axis viewed jet, in agreement with the predictions made for XRR by some models, and the latter with an energy injection equivalent in intensity to the initial shock. The analysis of the spectral flux distribution reveals an extinction compatible with a low chemical enrichment surrounding the burst. Together with the detection of an underlying starburst host galaxy we can strengthen the link between XRR and classical long-duration bursts.

XSS J00564+4548 and IGR J00234+6141: New cataclysmic variables from the RXTE and INTEGRAL all-sky surveys

We present the results of our optical identification of two X-ray sources from the RXTE and INTEGRAL all-sky surveys: XSS J00564+4548 and IGR J00234+6141. Using optical observations with the 1.5-m Russian-Turkish Telescope (RTT150) and publicly accessible X-ray data from the SWIFT Orbital Observatory, we show that these sources are most likely intermediate polars, i.e., binary systems with accreting white dwarfs that possess a moderately strong magnetic field (≲10 MG). We have found periodic optical oscillations with periods of ≈480 and ≈570 s. These periods most likely correspond to the rotation periods of the white dwarfs in these systems. Further optical RTT150 observations of these systems will allow their parameters to be studied in more detail.

New active galactic nuclei among the INTEGRAL and SWIFT X-ray sources

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 NGC973. One source, IGRJ16562−3301, 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.We present the results of our optical identifications of a set of X-ray sources from the INTEGRAL and SWIFT all-sky surveys. The optical data have been obtained with the 1.5-m Russian-Turkish Telescope (RTT-150). Nine X-ray sources have been identified with active galactic nuclei (AGNs). Two of them are located in the nearby spiral galaxies MCG-01-05-047 and NGC 973 seen almost edge-on. One source, IGR J16562-3301, is probably a BL Lac object (blazar). The remaining AGNs are observed as the starlike nuclei of spiral galaxies whose spectra exhibit broad emission lines. The relation between the hard X-ray (17–60 keV) luminosity and the [O III] 5007 line luminosity, log Lx/L[O III] ≈ 2.1, holds good for most of the AGNs detected in hard X rays. However, the luminosities of some AGNs deviate from this relation. The fraction of such objects can reach ∼20%. In particular, the [O III] line flux is lower for two nearby edge-on spiral galaxies. This can be explained by the effect of absorption in the galactic disks.