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We analyze observations of the compact GHZ-peaked-spectrum radio source in the nucleus of the weakly active galaxy NGC 1052,
assuming that the low-frequency turnover in its spectrum is due to synchrotron self-absorption. The analysis is based on a
model for an inhomogeneous source of synchrotron radiation. It is shown that the magnetic field is not uniform, but the change
in the field strength from the center to the edge of the compact radio source does not exceed an order of magnitude. The maximum
magnetic-field strength in the nucleus of NGC 1052 is 20 G < H
⊥ < 200 G, and the density of relativistic electrons is 0.018 cm−3 < n
e
< 0.18 cm−3 on scales of 0.1 pc; everywhere in the radio source, the energy density of the magnetic field exceeds the energy density
of the relativistic electrons. The physical conditions are similar to those in the nuclei of the nearby radio galaxies 3C
111 and 3C 465, and differ strongly from those in the nucleus of the radio galaxy 0108+388, which is a compact GHz-peaked-spectrum
source (these three galaxies were studied by the authors earlier using the same method). 相似文献
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It is shown that composite radio spectra of the hot spots of the radio galaxy Cygnus A can be fully explained by assuming a nonuniform distribution of the magnetic fields inside the hot spots, without invoking any physical mechanisms other than synchrotron radiation. The magnetic fields are strong (B ?? 10?2?10?1 G) at the center of the hot spots, and decreases at the hot-spot edges to the level of the magnetic field of the radio lobes in which the hot spots are embedded (B ?? 10?4?10?5 G). The difference in the magnetic field between the hot-spot center and edge decreases during the evolution, while the average magnetic-field intensity increases. 相似文献
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V. I. Shishov S. A. Tyul’bashev V. S. Artyukh I. A. Subaev I. V. Chashei P. A. Chernikov 《Solar System Research》2005,39(4):333-338
It is proposed to use the coefficient of asymmetry of the distribution function of fluctuations of a scintillating source flux density as a parameter that characterizes interplanetary turbulent plasma. It is demonstrated that this parameter can be measured with a differential method and that its informative capacity is equivalent to that of the source scintillation index. A series of test observations of scintillations was performed with the Large Phased Array antenna of the Lebedev Institute of Physics, Russian Academy of Sciences, simultaneously with measurements of the source scintillation indices and coefficients of asymmetry. Comparative analysis of the measured quantities showed that the coefficient of asymmetry within a numerical coefficient equals the source scintillation index, normalized to the flux density of the scintillating component. The coefficient of asymmetry makes it possible to restore scintillation indices when the radio sources are weak and it is difficult to measure their mean flux densities, and, hence, it enlarges the number of observable scintillating sources and makes the exploration of interplanetary plasma by means of the mapping of scintillation indices more efficient.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 4, 2005, pp. 375–380.Original Russian Text Copyright © 2005 by Shishov, Tyul’bashev, Artyukh, Subaev, Chashei, Chernikov. 相似文献
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Results of radio observations of luminous and ultraluminous infrared galaxies are discussed. The declining or flattening of the radio spectra of compact and (in some cases) extended sources found using interplanetary scintillation observations at 102 MHz is accounted for by absorption in thermal plasma, in agreement with the observed brightness of optical emission lines. It is argued that a region of violent star formation occupies the area of a molecular disc 1 kpc in size. The discrepancy between the linear sizes of the compact radio sources and the star forming regions is discussed. 相似文献
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Some features of the low-frequency cut-offs of synchrotron radio spectra are investigated using numerical simulations. It is demonstrated that the interpretation of the radio spectra of compact sources must be based on an exact (numerical) solution of the transfer equation. The need for creating VLBI systems operating at meter wavelengths to study the physical conditions in galactic nuclei is justified. 相似文献
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A new method for estimating the physical parameters of active galactic nuclei involving the analysis of observations of the compact radio sources in them is proposed. The method is based on an inhomogeneous model for a synchrotron radio source. Theoretical spectra of the radio sources are obtained via numerical solution of the transfer equation. Due to the paucity of observational data, only interval estimates of the magnetic field strength and the energy densities of the magnetic field and relativistic particles can be obtained. A mechanism for the formation of flat radio spectra is proposed. 相似文献
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V. S. Artyukh 《Astronomy Reports》2000,44(6):349-352
A correlation analysis for a survey of compact radio sources (～0.1″) is presented. The survey is based on interplanetary-scintillation observations carried out at 102 MHz on the Large Phased Array of the Lebedev Physical Institute. The survey area covers 0.1 ster centered on the direction α=10h28m and δ=41°. The distribution of scintillating sources is uniform on scales 1°相似文献