Extragalactic sources with asymmetric radio structure II. further observations of the quasar B2 1320 + 299

1986 ◽  
Vol 7 (2) ◽  
pp. 119-129 ◽  
Author(s):  
T. J. Cornwell ◽  
D. J. Saikia ◽  
P. Shastri ◽  
L. Feretti ◽  
G. Giovannini ◽  
...  
Keyword(s):  
2001 ◽  
Vol 546 (1) ◽  
pp. 447-454 ◽  
Author(s):  
John R. Dickel ◽  
Richard G. Strom ◽  
D. K. Milne

2021 ◽  
Vol 922 (2) ◽  
pp. 197
Author(s):  
Anna Wójtowicz ◽  
Łukasz Stawarz ◽  
Jerzy Machalski ◽  
Luisa Ostorero

Abstract The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FR II type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e., sampling the broadband radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here, we analyze the best-fit values of the source physical parameters, derived from extensive modeling of the largest currently available sample of FR II radio sources, for which good-quality multiwavelength radio flux measurements could be collected. In the analyzed data set, we notice a significant and nonobvious correlation between the spectral index of the nonthermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely, the slope of the radio continuum between the rest-frame frequencies 0.4 and 5 GHz, possibly combined with the total linear size of the radio structure.


2021 ◽  
Vol 26 (2) ◽  
pp. 165-172
Author(s):  
A. P. Miroshnichenko ◽  

Purpose: Estimate of the environment density of giant (with the linear size of about megaparsec) radio structures for galaxies and quasars with steep low-frequency spectra taken from the UTR-2 catalogue. Study of the cosmological evolution of environment density of giant radio sources. Determination of dependence of contribution of radio lobes into the emission of giant sources with respect to their environment density. Design/methodology/approach: We use the sample of sources from the UTR-2 catalogue of extragalactic sources to estimate the environment density for giant sources with steep low-frequency spectra. The selection criteria for the examined objects are the following: 1) the spectral index value is equal or larger than 1; 2) the fl ux density of emission at the frequency of 25 MHz is larger than 10 Jy; 3) the sample sources are optically identifi ed. The value of environment density of examined sources is obtained with the assumption of equality of source jet luminosity (at the synchrotron mechanism of radio emission) and its corresponding kinetic luminosity. The analysis of the estimates of environment densities is made for different classes of the sample objects (for galaxies and quasars with linear steep spectra and with break steep spectra). Findings: The estimates of environment density have been derived for giant radio structures formed by the jets of sources with steep spectrum from the UTR-2 catalogue. On the average, the environment density for the quasar structure (~ 10-28 g/sm3) is lesser than the one for the galaxies (~ 10-27 g/sm3 to ~ 10-26 g/sm3). The larger jet environment density is typical for the galaxies and quasars with the break steep spectra than for those with the linear steep spectra. The inverse power relation of the jet environment density and the source redshift (the cosmological evolution of the jet environment density) has been derived. The contribution of jet-related radio lobes into the emission of sources displays the inverse power relation for the environment density of the corresponding radio structures. Conclusions: The mean values of obtained estimates of environment density of giant jets of radio sources with steep low-frequency spectra indicate the lesser environment density of quasar jets than that for the galaxy jets. Giant radio sources with steep low-frequency spectrum (especially, with break steep spectrum) reveal considerable evolution of environment density of jets. The larger contribution of radio lobes (jets) into the emission of sources corresponds to the lesser environment density of sources taken from the UTR-2 catalogue. It can be due to propagation of jets (surrounded by radio lobes) from powerful radio sources to distances of about megaparsec, until the balance of source’s environment density and extragalactic environment density is reached. Key words: steep low-frequency radio spectrum; giant radio structure; jets; radio lobes; galaxies; quasars; environment density


2008 ◽  
Vol 131 ◽  
pp. 012042
Author(s):  
Jens Zuther ◽  
Sebastian Fischer ◽  
Andreas Eckart
Keyword(s):  

Author(s):  
Norbert Junkes ◽  
Raymond F. Haynes ◽  
Julienne I. Harnett

1990 ◽  
Vol 124 ◽  
pp. 331-342
Author(s):  
I. Pronik ◽  
L. Metik

AbstractSome pecularities of the circummucleus of the Seyfert galaxy NGC 7469 were revealed, plausibly caused by interaction with the satellite IC 5283 and a starlike detail, situated on the edge of the west spiral branch 14” from the nucleus. Shock excited HII regions were noted in the part of NGC 7469 turned toward the satellite IC 5283. The galaxy’s central radio structure (λ ~ 6 cm) stretches in the direction toward the satellite IC 5283 and the starlike detail. The spectum and color index of the starlike detail suggest that it is a cluster of early type stars (Mv = -19m) and dust clouds (Av = 3m), in NGC 7469.


1983 ◽  
Vol 101 ◽  
pp. 253-260
Author(s):  
W. H.-M. Ku ◽  
K. Long ◽  
R. Pisarski ◽  
M. Vartanian

High quality X-ray spectral and imaging observations of the Cygnus Loop have been obtained with three different instruments. The High Resolution Imager (HRI) on the Einstein Observatory was used to obtain arcsecond resolution images of select bright regions in the Cygnus Loop which permit detailed comparisons between the X-ray, optical, and radio structure of the Loop. The Imaging Proportional Counter (IPC) on the Einstein Observatory was used to obtain an arcminute resolution map of essentially the full Loop structure. Finally, an Imaging Gas Scintillation Proportional Counter (IGSPC), carried aloft by a sounding rocket last fall, obtained modest resolution, spatially resolved spectrophotometry of the Cygnus Loop. An X-ray map of the Loop in the energy of the 0 VIII line was obtained. These data combine to yield a very powerful probe of the abundance, temperature, and density distribution of material in the supernova remnant, and in the interstellar medium.


1984 ◽  
Vol 110 ◽  
pp. 141-143 ◽  
Author(s):  
T.W.B. Muxlow ◽  
M. Jullian ◽  
R. Linfield

Models are here presented interpreting the arcsecond radio structure found in the quasar 3C418 as a precessing jet. No simple solution exists and it has been found necessary to complicate the model geometry by allowing the precession cone-angle to increase with time. The timescales suggest the presence of a close binary black-hole system within the quasar core. The modelled behaviour of the precession cone close to the core is explained either by interaction of the jet with the surrounding galactic material or by the observation of the source during the capture of one black-hole by the other.


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