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1.
We discuss the results of deep surveys of a ±10′ strip of the sky, centered on the declination of SS 433, carried out on the Northern sector of the RATAN-600 telescope at 2.7 and 7.6 cm in 1987–2000. The survey objects are cross-identified with sources in the NVSS catalog and the corresponding two-frequency spectral indices determined. We find a decrease in the mean spectral index in the transition from objects with flux densities S 21 ≥ 30 mJy to those with 15 < S 21 < 30 mJy. The constructed log N — logS relation at 2.7 cm has a slope of 3/2 at flux densities ≥300 mJy and flattens at weaker flux densities. The 1.4 GHz (NVSS), 3.94 GHz (RATAN-600), and 11.11 GHz (RATAN-600) data are used to estimate the number of objects per square degree at a wavelength of 1 cm. 相似文献
2.
Radio sources detected at 3.94 GHz in RATAN-600 observations made in 1980–1981 (the KHOLOD Survey) have been identified with objects from the NVSS catalog down to 5 mJy at 1.4 GHz, and their spectral indices have been estimated. Of the 1311 NVSS objects in the KHOLOD survey region, 836 are present in both catalogs. The average flux density of the common objects is 40 mJy, and the median flux density is 14 mJy. The average spectral indices of these objects for four flux-density intervals were calculated. The average spectral index grows with flux density. The fraction of objects with inverted spectra is 2–4%, and the average flux density of these sources is about 10 mJy. Optical identifications of the NVS S objects in the KHOLOD survey region have been carried out to R=20.5m using the Palomar plates. About 20% of the radio sources are identified with optical objects in all the radio flux-density intervals. 相似文献
3.
We present the results of observations of a complete sample of radio sources with the RATAN-600 radio telescope at 0.97, 2.3, 3.9, 7.7, 11.1, and 21.7 GHz. The sample was extracted from the GB6 catalog at 4.85 GHz, and contains all the sources at declinations 74°–75° (J2000) with flux densities S 4.85 > 100 mJy. We have obtained optical identifications for 67% of the radio sources with flat spectra and 30% of those with steep spectra. 相似文献
4.
Radio Sources in the Central Section of the RZF Catalog. Search for Objects with Ultra-Steep Spectra
Results of reducing and selecting data from the Ratan Zenith Field (RZF) are presented. A deep survey in the region 0h ≤ R.A. ≤ 24h, 40.5° ≤ DEC ≤ 42.5° carried out on the RATAN-600 radio telescope was used. Within +2′ of the center of the survey region, 448 objects were detected, 69 of them with ultra-steep spectra (USS). The SDSS digital optical survey (DR12), NVSS radio maps, and the FIRST catalogs have been used to cross-identify 208 radio sources from the RZF catalog, obtained as part of the “Genetic Code of the Universe” project. The characteristics of these objects are studied, and the distribution of the SDSS galaxies in a two-color diagram is obtained. Photometric redshifts and radio luminosities at 3940 and 1400 MHz are determined for 27 objects with spectral indices α < −1.1 (S ∝ να) for which magnitudes in various filters are presented in the SDSS. In the sample of USS objects, 12 galaxies have redshifts z < 0.5, are detected at wavelength λ = 7.6 cm, and have relatively high radio luminosities (type FR II or intermediate type FR I–FR II). Only one radio galaxy proved to be a rare nearby galaxy with relatively low radio luminosity L1400 MHz = 1.51 × 1024 W/Hz (type FR I). Two objects are candidate GHz-Peaked Spectrum objects.
相似文献5.
M. G. Mingaliev Yu. V. Sotnikova N. S. Kardashev M. G. Larionov 《Astronomy Reports》2009,53(6):487-500
We present the results of our observations of compact extragalactic radio sources near the north celestial pole (+75° ≤ δ ≤ +88°) obtained on the RATAN-600 radio telescope. Our sample consists of 51 radio sources with spectra that are either flat or inverted (growing toward shorter wavelengths) and with flux densities at 1.4 GHz S ν ≥ 200 mJy. We observed the sources at 1–21.7 GHz. Multi-frequency instantaneous spectra are presented for 1999–2007. We observed 33 of our sample source daily for 30 days in August 2007. As a result, we revealed 15 objects exhibiting rapid variations on time scales of a day. The multi-frequency instantaneous spectra of these sources indicate that radio flux variations on one-day timescales are characteristic of objects of various spectral types. More than half the sources exhibiting rapid variations demonstrate a growth in the variability amplitude with increasing frequency. For some of the objects, the variability amplitude is virtually independent of frequency. 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》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
7.
Yu. N. Pariiskii N. S. Soboleva A. V. Temirova N. N. Bursov O. P. Zhelenkova 《Astronomy Reports》2012,56(5):336-344
Published data from long-term observations of a strip of sky at declination ?? ?? 5° carried out at 7.6 cm on the RATAN-600 radio telescope are used to estimate some statistical properties of radio sources. Limits on the sensitivity of the survey due to noise imposed by background sources, which dominates the radiometer sensitivity, are refined. The vast majority of noise due to background sources is associated with known radio sources (for example, from the NVSS with a detection threshold of 2.3 mJy) with normal steep spectra (?? = 0.7?C0.8, S ?? ?? ??? ), which have also been detected in new deep surveys at decimeter wavelengths. When all such objects are removed from the observational data, this leaves another noise component that is observed to be roughly identical in independent groups of observations. We suggest this represents a new population of radio sources that are not present in known catalogs at the 0.6 mJy level at 7.6 cm. The studied redshift dependence of the number of steep-spectrum objects shows that the sensitivity of our survey is sufficient to detect powerful FRII radio sources at any redshift, right to the epoch of formation of the first galaxies. The inferred new population is most likely associated with low-luminosity objects at redshifts z < 1. In spite of the appearance of new means of carrying out direct studies of distant galaxies, searches for objects with very high redshifts among steep and ultra-steep spectrum radio sources remains an effective method for studying the early Universe. 相似文献
8.
M. L. Khabibullina O. V. Verkhodanov M. Singh A. Pirya N. V. Verkhodanova S. Nandi 《Astronomy Reports》2010,54(7):571-577
Measurements of the flux densities of the extended components of seven giant radio galaxies obtained using the RATAN-600 radio
telescope at wavelengths of 6.25 and 13 cm are presented. The spectra of components of these radio galaxies are constructed
using these new RATAN-600 data together with data from the WENSS, NVSS, and GB6 surveys. The spectral indices in the studied
frequency range are calculated, and the need for detailed estimates of the integrated contribution of such objects to the
background emission is demonstrated. 相似文献
9.
The results of 0.97, 2.3, 3.9, 7.7, 11.1, and 21.7 GHz observations of a complete sample of radio sources obtained on the RATAN-600 radio telescope are presented. The sample is comprised of sources from the 4.85-GHz MGB survey, and contains all sources at declinations 10°–12°30′ (J2000) with Galactic latitudes |b|>15° and flux densities S4.85>200 mJy. Optical identifications have been obtained for about 86% of the radio sources with flat spectra and 59% of those with steep spectra. The spectra of the flat-spectrum sources have been decomposed into extended and compact components. 相似文献
10.
V. L. Afanas’ev S. N. Dodonov A. V. Moiseev A. G. Gorshkov V. K. Konnikova M. G. Mingaliev 《Astronomy Reports》2009,53(4):287-294
We present classifications, optical identifications, and radio spectra for eight radio sources from three flux-density-complete samples in the following declination ranges: 4°–6° (B1950), S 3.9 > 200 mJy; 10°–12°30′ (J2000), S 4.85 > 200 mJy; 74°?75° (J2000), S 4.85 > 100 mJy. For all these samples, the right ascensions are 0h–24h and the Galactic latitudes, |b| > 15°. Our optical observations at 4000–7500 ° were made with the 6-m telescope of the Special Astrophysical Observatory; we also observed at 0.97–21.7 GHz with the RATAN-600 radio telescope of the Special Astrophysical Observatory. We classify four of the objects as quasars and four as galaxies. Five of the radio sources have power-law spectra at 0.97–21.7 GHz, while two objects have flat spectra. The quasar J2358+0430 virtually did not vary during 23 years. 相似文献
11.
M. A. Kharinov A. M. Finkel’shteĭn A. V. Ipatov O. A. Tsiopa Yu. N. Gnedin M. Yu. Piotrovich 《Astronomy Reports》2010,54(9):853-860
Results of radio observations of the cosmic gamma-ray burst GRB 080319B at 8.45 GHz during the afterglow are reported. The
observations were carried out on telescopes of the Zelenchukskaya and Svetloe Observatories of the Institute of Applied Astronomy,
Russian Academy of Sciences. Two outbursts in the radio brightness were detected in the afterglow of GRB 080319B. A total
of 148 radio observations were performed at 3.5, 6.2, and 13 cm. The observations were conducted in a mode with smooth scanning
in elevation, which was also used to update the flux densities of the primary reference sources. The first powerful radio
outburst was recorded on March 28, 2008, 6.86d after the gamma-ray burst, when the maximum flux density was F
8.45 GHz = 44 ± 12 mJy. Almost two months later, a second increase in the radio brightness was observed. The flux density monotonically
increased from 19 mJy (59.55d) to 34mJy (59.79d) over 6.5 h; 1.17 d later, the flux density fell to 12mJy.At this last epoch, the radio flux demonstrated variability within
3σ on timescales of 9d−10d. The detected radio brightness increases are interpreted in terms of MHD interactions of a fast plasma outflow with a cloud
of inhomogeneous surrounding medium. This interaction is accompanied by restructuring of the relativistic plasma outflow;
the analysis of this process has been carried out. 相似文献
12.
M. G. Mingaliev Yu. V. Sotnikova N. N. Bursov N. S. Kardashev M. G. Larionov 《Astronomy Reports》2007,51(5):343-363
We have used the RATAN-600 radio telescope to study the spectral characteristics of a uniform sample of 504 radio sources from the NVSS catalog near the North Celestial Pole at six frequencies from 1.1 to 21.7 GHz, with the aim of selecting sources possessing inverted spectra near 22 GHz, to be included in the program of the Radio Astron future space VLBI mission. We found 17 radio sources with the desired spectral characteristics. Data from spectral studies over a wide wavelength range testify that the spectral behavior of our sample differs from that for a complete sample of sources with the same initial parameters but selected at 20 GHz. We find a 6% deficit of inverted-spectrum sources, which can be explained as an effect of the spectral characteristics of “sub-threshold” sources that were not included in the initial sample at 1.4 GHz. 相似文献
13.
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
14.
The paper reports the results of ten-year centimeter-wavelength observations with the RATAN-600 radio telescope of a complete sample of 83 flat-spectrum sources from the GB6 catalog of the MGB Survey, with S 4.85 > 200 mJy at declinations 10°?C12°30??. Starting in 2000, the observations were conducted simultaneously at six frequencies in the range 0.97?C21.7 GHz. Seventy-six sources (including 54 quasars) have been identified with optical objects, which have redshifts in the range z = 0.331?C3.601. Analysis of light curves and spectra at different activity phases has shown that, in most cases, the dynamics of the development of flares is consistent with a model in which the variability results from the evolution of a shock in a radio jet. A relationship between the time scales for the rise and fall of the flares has been found. There is no redshift dependence of the true linear dimensions of the radiating regions and the variability indices obtained over ten years. These facts can be interpreted as an absence of cosmological evolution of quasars at least up to z ?? 3. 相似文献
15.
A search for giant radio sources has been carried out using the PC102 catalog, which was compiled from a survey of the northern sky at 102.5 MHz. 117 extended sources were detected in an area with right ascensions 0h?4h and declinations from ?17? to +82?. Half of these sources have linear sizes in the plane of the sky of more than 500 kpc. A catalog of giant radio sources that is complete for radio sources with redshifts less than 0.2 has been compiled. 相似文献
16.
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
17.
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
18.
Results of centimeter-wavelength RATAN-600 observations of several hundred NVSS objects with a wide range of flux densities are presented. Changes in spectral-index distributions from strong-to faint-object populations are estimated. In the transition from strong to faint radio sources, the number of steep-and ultrasteep-spectrum objects decreases and the minimum between steep-and flat-spectrum objects, which was first discovered in the 1970s, becomes less distinct. A less certain increase in the fraction of inverted-spectrum objects is also found. Comparison with theoretical models of radio-source evolution suggests that the decrease in the number of steep-and ultrasteep-spectrum objects can be naturally explained by a sharp decrease in the fraction of classical FRII radio galaxies. The decrease in the sharpness of the minimum may be due to the growing contribution from the population with spectral indices 0.7–0.5, which is usually identified with starbust galaxies. The small increase in the fraction of inverted-spectrum radio sources can be attributed to the growing number of objects with active nuclei. Our spectrum-based conclusions are confirmed by the morphology of the FIRST Catalog images. The number of radio sources associated with supermassive black holes in the Early Universe is estimated using data from the SDSS Catalog. 相似文献
19.
M. L. Khabibullina O. V. Verkhodanov M. Singh A. Pirya S. Nandi N. V. Verkhodanova 《Astronomy Reports》2011,55(5):392-399
Results of RATAN-600 centimeter-wavelength flux-density measurements of the extended components in five giant radio galaxies
are reported. The spectra of the components of these radio galaxies have been constructed using the data of the WENSS, NVSS,
and GB6 surveys together with new RATAN-600 data. Spectral indices in the studied frequency range have been calculated. 相似文献
20.
Results of observations of the five candidate GPS sources J0626+8202, J0726+7911, J1044+8054, J1823+7938, and J1935+8130 are
presented. GPS sources are extragalactic sources whose spectral peaks are near several GHz. These objects were observed on
the RATAN-600 radio telescope from 1999 through 2010 at 1.1, 2.3, 4.8, 7.7, 11.2, and 21.7 GHz. These radio sources were selected
from a complete sample (S
v
≥ 200 mJy at 1.4 GHz) in the vicinity of the North Celestial Pole (+75° ≤ δ ≤ +88°); four are considered as GPS candidates for the first time here. Their spectral properties, variability and morphology
are analyzed, and confirms that these can be classified as GPS sources. These four to five GPS sources probably comprise a
complete sample of this class of object in this region of the celestial sphere. 相似文献