233 research outputs found
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
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))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
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
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
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
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
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
Observations of the optical afterglow from GRB 060526 with the RTT-150 telescope
Multicolor photometric observations of the optical afterglow from GRB 060526 with the Russian-Turkish 1.5-m RTT-150 telescope (Mount Bakyrlytepe, Turkey) are presented. The afterglow light curve was measured in detail starting from about 5 h after the GRB and over five ensuing nights. In addition, upper limits were obtained on the rapid variability of the afterglow on the first night of observations and the history of afterglow color variations was measured in detail. In the time interval from 6 to 16 h after the burst, the flux gradually decreased approximately as a power law with a slope of -1.14 ± 0.02. Subsequently, variability was observed on a time scale δt < t and the afterglow began to decay much faster. The afterglow color was approximately constant (V-R ≈ 0.5) throughout the observations, despite the flux variability. Variability time scales up to δt/t ≈ 0.0055 were observed at ΔF ν/F ν ≈ 0.3, which violates many constraints on the variability of the observed emission from an ultrarelativistic jet obtained by Ioka et al. (2005). We suggest explaining this variability by the fact that the shell motion is no longer ultrarelativistic at this time. © 2007 Pleiades Publishing, Inc
First simultanous X-ray and optical observations of rapid variability of supercritical accretor SS433
We present results of first simultaneous optical and X-ray observations of peculiar binary system SS433. For the first time, chaotic variability of SS433 in the optical spectral band (R band) on time scales as small as tens of seconds was detected. We find that the X-ray flux of SS433 is delayed with respect to the optical emission by approximately 80 s. Such a delay can be interpreted as the travel time of mass accretion rate perturbations from the jet base to the observed X-ray emitting region. In this model, the length of the supercritical accretion disk funnel in SS433 is ∼1012 cm
- …