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1.
We present the results of twenty-year observations of a complete sample of 68 flat-spectrum radio sources with flux densities S 3.9 GHz > 200 mJy carried out at centimeter wavelengths with the RATAN-600 radio telescope. Since 1995, we have observed simultaneously at six frequencies between 0.97 and 21.7 GHz. Of the 56 sources identified with optical objects, 41 are quasars with redshifts between 0.293 and 3.263. Based on our analysis of the spectral shapes, we divide the sources into four classes. Changes of spectral class for individual sources are fairly rare. Based on the light curves and spectra, in most cases, a flare’s evolution is in accordance with a model in which the variations result from the evolution of a shock in the radio jet. The main result of our study is that there is no redshift dependence for the true linear sizes of the radiating regions, the variability indices derived for all 20 years of data or for individual flares, or the peak frequencies of the spectra of the compact radio emission. We suggest that this testifies to an absence of cosmological evolution of the sample quasars, at least to z ≈ 3. 相似文献
2.
V. L. Afanas’ev S. N. Dodonov A. V. Moiseev A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Reports》2006,50(4):255-272
We present classifications, optical identifications, and radio spectra for 19 radio sources from three complete samples, with declinations 4°–6° (B1950, S 3.9 GHz > 200 mJy), 10°–12°30′ (J2000, S 4.85 GHz > 200 mJy), and 74°–75° (J2000, S 4.85 GHz > 100 mJy). We also present corresponding information for the radio source J0527+0331. The right ascensions are 0–24h and the Galactic latitudes |b| > 15° for all the samples. Our observations were obtained with the 6 m telescope from the Special Astrophysical Observatory in the range 4000–9000 Å or 4000–7500 Å and the RATAN-600 radio telescope at frequencies in the range 0.97–21.7 GHz. We obtained flux densities for the radio sources and optical spectra for their optical counterparts. Nine objects were classified as quasars with redshifts from z = 1.029 to 3.212; nine objects are emission-line galaxies with redshifts from 0.172 to 0.546, and one is a galaxy with burstlike star formation at z = 0.156, and one is a BL Lac object with z = 0.509. The spectra of five radio sources were decomposed into extended and compact components. The radio source J0527+0331, identified with a BL Lac object, displays significant variations of time scales from several days to several years. Data on flux variations are presented for 11 radio sources, as well as their spectra at several epochs. 相似文献
3.
A. G. Gorshkov A. V. Ipatov V. K. Konnikova V. V. Mardyshkin M. G. Mingaliev M. A. Kharinov 《Astronomy Reports》2014,58(10):716-724
Results of the observations of the blazar J1159+2914 (S1156+295) in 2010–2013 are reported. The observations were carried out on the RATAN-600 radio telescope (Special Astrophysical Observatory, Russian Academy of Sciences) at 4.85, 7.7, 11.1, and 21.7 GHz and the 32-m Zelenchuk and Badary radio telescopes of the Quasar-KVO Complex (Institute of Applied Astronomy, Russian Academy of Sciences) at 4.85 and 8.57 GHz. A flare peaked in August 2010, after which the flux density decreased monotonically at all studied frequencies. Variability on a timescale of 7 days was detected at 7.7 and 11.1 GHz near the flare maximum. The delay in the maximum at 7.7 GHz relative to the maximum at 11.1 GHz was 1.5 d, implying a Lorentz factor γ = 55 and angle of the jet to the line of sight θ ≈ 2° since mid-2011. Searches for intraday variability (IDV) were undertaken by the 32-m telescopes, mostly since mid-2011. Intraday variability was confidently detected only at the Badary station on November 10–11, 2012 at 4.85 GHz: the IDV timescale was τ acf = 6 h, the modulation index was m = 1.4%, and the flux density of the variable component was S var = 126 mJy. 相似文献
4.
V. Chavushyan R. Mujica A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Letters》2000,26(6):339-343
We obtained optical spectra of four objects identified with variable radio sources. Three objects (0029+0554, 0400+0550, 2245+0500) were found to be quasars with redshifts of 1.314, 0.761, and 1.091. One object (2349+0534) has a continuum spectrum characteristic of BL Lac objects. We analyze spectra of the radio sources in the range 0.97–21.7 GHz for the epoch 1997 and in the range 3.9–11.1 GHz for the epoch 1990, as well as the pattern of variability of their flux densities on time scales of 1.5 and 7 years. 相似文献
5.
Results of a study of the variability of radio sources on timescales of 3–30 days based on six sets of daily observations
on the RATAN-600 radio telescope with durations from 53 to 103 days at six frequencies from 0.97 to 21.7 GHz are reported.
The variability timescales and spectra determined from the analysis of light curves, structure functions, and autocorrelation
functions for 11 radio sources from a complete sample in the declination range 4°–6° (B1950) are presented. 相似文献
6.
V. L. Afanas’ev S. N. Dodonov A. V. Moiseev A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Reports》2003,47(6):458-466
Optical identifications and an analysis of the radio spectra of eight radio sources from a flux-density-complete sample at declinations 4°–6° (B 1950) are presented. The observations were carried out at 4000–9000 Å on the 6-m telescope of the Special Astrophysical Observatory and at 0.97–21.7 GHz on the RATAN-600 telescope. Five of the eight sources are quasars and three are emission-line radio galaxies. 相似文献
7.
V. Chavushyan R. Mujica J. R. Valdes A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Reports》2002,46(9):697-703
Classifications of the optical counterparts and radio spectra of nine radio sources are presented. The observations were carried out using the 2.1-m optical telescope in Cananea (Mexico) at 4200–9000 Å and the RATAN-600 radio telescope at 0.97–21.7 GHz. Five objects have been classified as quasars (three have redshifts z>2), two as BL Lac objects, one as an elliptical galaxy, and one as an absorption-line galaxy. 相似文献
8.
The results of observations of a complete sample of radio sources with spectral indices α>?0.5 (S∝v α) are presented. The sample was selected from the Zelenchuk Survey at 3.9 GHz and contains all sources with declinations 4°–6°, Galactic latitudes |b|>10°, and 3.9-GHz fluxes >200 mJy. Spectra at 0.97–21.7 GHz were obtained for all 69 sample sources. The spectra were classified, and a correlation between variability amplitude and spectrum shape was found. The spectra were separated into extended and compact components. The distribution of spectral indices α for the extended components coincides with the distribution for sources with power-law spectra. The correlation between the luminosity and frequency of the peak flux density is confirmed. This correlation is due to the fact that the distribution of source linear dimensions does not depend on luminosity. 相似文献
9.
A. G. Gorshkov A. V. Ipatov V. K. Konnikova A. L?hteenm?ki V. V. Mardyshkin M. G. Mingaliev E. Nieppola J. Tammi A. M. Finkel’shtein M. A. Kharinov 《Astronomy Reports》2011,55(12):1096-1104
Results of a study of the variability of the blazar J0721+7120 carried out on the RATAN-600 based on daily observations from
March 5, 2010 to April 30, 2010 at five frequencies from 2.3 to 21.7 GHz are reported. In the same time interval, 13 observing
sessions at 37 GHz were carried out on the 14-m radio telescope of the Mets?hovi Radio Astronomy Observatory of the Aalto
University School of Technology (Finland). From March 19, 2010 to October 20, 2010, 16 daily sessions at 6.2 cm and five sessions
at 3.5 cm were conducted on the 32-m radio telescope of the Zelenchukskaya Observatory (Quasar-KVO complex of the Institute
of Applied Astronomy, Russian Academy of Sciences). A powerful flare was detected during the observations, with a time scale
of approximately 20 days, derived from an analysis of the light curves and the structure and autocorrelation functions. The
flare spectrum has been determined. In five sessions on the 32-m Zelenchukskaya telescope at 6.2 cm, intraday variability
with time scales 8-16 h was detected; in four sessions, trends with time scales longer than a day were observed. In three
sessions at 3.5 cm, intraday variability with a time scale of approximately 5 h was detected. 相似文献
10.
A. G. Gorshkov A. V. Ipatov V. K. Konnikova V. V. Mardyshkin M. G. Mingaliev A. M. Finkel’shtein M. A. Kharinov 《Astronomy Reports》2011,55(2):97-107
Results of a study of the variability of the BL Lac object S5 0716+714 are reported. The data were obtained in 150 daily observations
on the RATAN-600 radio telescope at six frequencies from 0.97 to 21.7 GHz and 13 day-long sessions at a wavelength of 6.2
cm on the 32 m radio telescopes of the Zelenchukskaya, Svetloe, and Badary observatories (Quasar-KVO complex, Institute of
Applied Astronomy, Russian Academy of Sciences). The RATAN-600 observations detected three “anti-flares,” or eclipses, when
the flux density decreased from an initially constant level and then returned to this level. The eclipse time scales obtained
from an analysis of light curves, structure functions, and autocorrelation functions are 12–20 days; the eclipse spectra were
determined. Intraday variability (IDV) with time scales of 10–12 hours was detected in three sessions on the 32-m radio telescopes. 相似文献