New integrable extension of the Hubbard chain with variable range hopping

New integrable variant of the one-dimensional Hubbard model with variable-range correlated hopping is studied. The Hamiltonian is constructed by applying the quantum inverse scattering method on the infinite interval at zero density to the one-parameter deformation of the L-matrix of the Hubbard model. By construction, this model has Y(su(2))$\oplus$Y(su(2)) symmetry in the infinite chain limit. Multiparticle eigenstates of the model are investigated through this method.Comment: 25 pages, LaTeX, no figure

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 \alpha=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.Comment: Astronomy Letters, Vol. 29, No. 9, p. 573; 6 pages, 5 figures; pagination corrected; the original Russian version can be found at http://hea.iki.rssi.ru/~br/030329/pfh030329.pd

Transient events in the near-nuclear regions of AGNs and quasars as the sources of the proper motion imitations

We present a sample of SRG/eROSITA X-ray sources located in the eastern Galactic hemisphere (0<l<180 deg), with significant proper motions according to GAIA eDR3 measurements and whose extragalactic nature has been confirmed. The catalog consists of 248 extragalactic sources with spectroscopically measured redshifts. It includes all objects available in the Simbad database and matched to the identified optical component within a radius of 0.5 arcsec. Additionally, the catalog includes 18 sources with the spectral redshift measurements based on observations at the Russian-Turkish 1.5-m telescope RTT-150. The sources of the catalog are AGNs of various types (Sy1, Sy2, LINER), quasars, radio galaxies, and star-forming galaxies. The imitation of significant proper motions can be explained (previously known in astrometry as the VIM effect) by the presence of transient events on the line of sight in the field of view of AGN nuclei and quasars (within the GAIA resolution element). Such astrophysical phenomena may be the supernovae outbursts, tidal destruction events in AGNs with double nuclei, variability of large-mass supergiants, the presence of O-B associations in field of view of variable brightness AGN, etc. A model of flares with a fast rise and exponential decay profile allows to describe the variable positional parameters of most similar sources observed in GAIA. This cross-matching approach of the X-ray source catalogs of the SRG/eROSITA observatory and the optical catalog of the GAIA observatory can be used as an independent technique for detecting transient events in the neighborhood of AGN core (on scales of several hundred parsecs in the picture plane).Comment: 23 pages, 8 figures, 10 table

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 of the Sunyaev-Zeldovich sources, that have been mostly identified by means of the optical observations performed previously by our team (Planck Collaboration, 2015a). The 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. The measurements were done using the data from Russian-Turkish 1.5-m telescope (RTT-150), 2.2-m Calar Alto Observatory telescope, and 6-m SAO RAS telescope (Bolshoy Teleskop Azimutalnyi, BTA).Comment: published in Astronomy Letter

Measurement of the Orbital Period of the X-ray Burster GS 1826-238 Based on Observations of Its Optical Brightness Variations

The variability of the optical and X-ray fluxes from the binary GS 1826-238 is investigated. An epoch-folding analysis of the optical data obtained with the RTT-150 telescope in 2003-2004 has revealed periodic brightness variations in the source with a period Porb = 2.24940 ± 0.00015 h with a high statistical significance. When estimating the detection significance of the periodic signal, we have specially taken into account the presence of a powerful aperiodic component ("red noise") in the source's brightness variability. The source's power density spectra in the frequency range ~10-5-0.01 Hz have been obtained. We have detected a statistically significant break in the power density spectrum of GS 1826-238 at a frequency νbr ≈ (8.48 ± 0.14) × 10-5 Hz in both optical and X-ray energy bands. We have estimated the orbital period of the binary GS 1826-238 using the correlation between the break frequency in the power density spectrum and the orbital period of binaries, Porb ∝ 1/νbr, found by Gilfanov and Arefiev (2005): Porb = 3.7 ± 0.8 h and Porb = 11.3 ± 5.9 h when using Sco X-1 and 1H 16267-273, respectively, as reference sources. It seems to us that the method for estimating the orbital periods of low-mass X-ray binaries using the correlation Porb ∝ 1/νbr may turn out to be very promising, especially for persistent low-luminosity X-ray binaries. © 2010 Pleiades Publishing, Ltd

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 \delta t < 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 \delta t/t =~ 0.0055 at \Delta F_\nu/F_\nu =~ 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.Comment: 6 pages, 7 figures, Astronomy Letters, 2007, 33, 797, The on-line data tables and the original text in Russian can be found at http://hea.iki.rssi.ru/grb/060526/indexeng.htm

Optical observations of SBS1520+530 at TUG

We present the light curves of the components of gravitationally lensed source SBS1520+530 in Rc band, obtained during the interval 2001-2005 with the 1.5 m Russian-Turkish Telescope RTT150 at TÜBITAK National Observatory of Turkey. The time delay of brightness fluctuations between the two components of the gravitationally double-imaged quasar corresponding to 2001-2002 period of observations is determined. Using all the available data, at least two microlensing events, one of them with long-time linear behavior and second one with duration of a few hundred days, are detected. © 2008 Springer-Verlag Berlin Heidelberg

Photometry and spectroscopy of IGR J21247+5058 radiogalaxy with RTT150

We present the results of photometry and spectroscopy of IGR J21247+5058 made by using the 1.5-m optical telescope RTTl50 with Andor CCD and TFOSC instrument. R-band images obtained at 0.8 arcsec seeing conditions have allowed us to separate foreground star from point-like extragalactic source and estimate their brightness separately. Low-resolution but high S/N ratio spectra of this optically combined source confirm the presence of red-shifted H-alpha emission line of extragalactic nature. Physical properties of radio-galaxy are briefly discussed

Comparative analysis of photometric variability of TT ARI in the years 1994-1995 and 2001, 2004

We present the results of photometric observations of a bright cataclysmic variable TT Ari with an orbital period of 0. 13755 days. CCD observations were carried out with the Russian-Turkish RTT 150 telescope in 2001 and 2004 (13 nights). Multi-color photoelectric observations of the system were obtained with the Zeiss 600 telescope of SAO RAS in 1994-1995 (6 nights). In 1994-1995, the photometric period of the system was smaller than the orbital one (0. d132 and 0. d134), whereas it exceeded the latter (0. d150 and 0. d148) in 2001, 2004. An additional period exceeding the orbital one (0. d144) is detected in 1995 modulations. We interpret it as indicating the elliptic disc precession in the direction of the orbital motion. In 1994, the variability in colors shows periods close to the orbital one (0. d136, b-v), as well as to the period indicating the elliptic disk precession (0. d146, w-b). We confirm that during the epochs characterized by photometric periods shorter than the orbital one, the quasi-periodic variability of TT Ari at time scales about 20 min is stronger than during epochs with long photometric periods. In general, the variability of the system can be described as a "red" noise with increased amplitudes of modulations at characteristic time scales of 10-40 min. © 2013 Pleiades Publishing, Ltd