Radio jets at high red shift

1986 ◽  
Vol 64 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Colin J. Lonsdale
Keyword(s):  
Red Shift ◽  
Radio Sources ◽  
Present Sample ◽  
Radio Jets ◽  
Flow Speeds ◽  
Relativistic Flow ◽  
Moving Jet ◽  
Luminosity Evolution ◽  
Radio Quasar ◽  
Observational Program

Using preliminary results from a large observational program targeting high red-shift radio quasars, we have increased the total number of radio jets known beyond a red shift of 1.5 from 5 to 26, thus generating one of the most uniform and complete samples of radio jets in existence. This sample enjoys relative freedom from cosmological and luminosity-evolution effects, which normally complicate statistical analyses of jets.An attempt has been made to test a type of radio-quasar model in which the appearance of a radio source is strongly influenced by its orientation relative to the line of sight, owing to Doppler boosting of the emission from relativistically moving jet material. Four "orientation indicators" are isolated, which should all be correlated with each other to some degree if the above-mentioned model is correct. It is found that only one pair of parameters shows a significant correlation, namely the jet prominence (relative to the lobes) and the jet curvature. This particular correlation finds a natural explanation in the physics of radio sources, and therefore may not be due to orientation effects.As a result of these findings, it is concluded that the present sample of high red-shift jets shows no evidence of relativistic flow speeds on kiloparsec scales.

scholarly journals Large Bent Jets in the Inner Region of CSS

1996 ◽  
Vol 175 ◽  
pp. 71-72
Author(s):  
F. Mantovani ◽  
W. Junor ◽  
M. Bondi ◽  
L. Padrielli ◽  
W. Cotton ◽  
...  
Keyword(s):  
Velocity Structure ◽  
Radio Sources ◽  
Ambient Media ◽  
The Core ◽  
Gaseous Environment ◽  
Radio Jets ◽  
Large Size ◽  
Superluminal Motion ◽  
Inner Region ◽  
Quasars And Radio Galaxies

Recently we focussed our attention on a sample of Compact Steep-spectrum Sources (CSSs) selected because of the large bent radio jets seen in the inner region of emission. The largest distortions are often seen in sources dominated by jets, and there are suggestions that this might to some extent be due to projection effects. However, superluminal motion is rare in CSSs. The only case we know of so far is 3C147 (Alef at al. 1990) with a mildly superluminal speed of ≃ 1.3v/c. Moreover, the core fractional luminosity in CSSs is ≃ 3% and ≤ 0.4% for quasars and radio galaxies respectively. Similar values are found for large size radio sources i.e. both boosting and orientations in the sky are similar for the two classes of objects. An alternative possibility is that these bent-jet sources might also be brightened by interactions with the ambient media. There are clear indications that intrinsic distortions due to interactions with a dense inhomogeneous gaseous environment play an important role. Observational support comes from the large RMs found in CSSs (Taylor et al. 1992; Mantovani et al. 1994; Junor et al. these proc.) and often associated with strong depolarization (Garrington & Akujor, t.p.). The CSSs also have very luminous Narrow Line Regions emission, with exceptional velocity structure (Gelderman, t.p.).

scholarly journals Time Dependent Energy Supply in Radio Sources and Morphology of Radio Lobes

1982 ◽  
Vol 97 ◽  
pp. 51-52
Author(s):  
W. A. Christiansen ◽  
A. G. Pacholczyk ◽  
John S. Scott
Keyword(s):  
Energy Supply ◽  
Morphological Features ◽  
Time Dependent ◽  
Radio Sources ◽  
Low Density ◽  
Background Medium ◽  
Radio Jets ◽  
Parent Galaxy

The fact that radio jets, which are often one-sided, are nevertheless associated with extended lobes of nearly equal luminosity indicates when analyzed in detail (1) that the energy supply by the nuclear engine to the lobes is strongly time-dependent. Time dependent ejection from the nucleus of a parent galaxy produces low density channels which are ploughed in the background medium by the passage of intermittently ejected radio emitting plasmons (2), (3), (4) and (5). An analysis of the dynamics of radio emitting plasmons in such channels leads to unique morphological features consistent with observations of both narrow jets (resulting from splashback or reflections from the channel ends) and conical lobes (resulting from slower hydrodynamic deceleration).

scholarly journals Optical Observations of Radio Jets

1980 ◽  
Vol 5 ◽  
pp. 671-675
Author(s):  
Wil van Breugel ◽  
George Miley ◽  
Harvey R. Butcher
Keyword(s):  
Energy Transport ◽  
Optical Observations ◽  
Radio Sources ◽  
Optical Counterpart ◽  
Radio Structure ◽  
The Past ◽  
Radio Jets ◽  
Extended Radio ◽  
Considerable Body ◽  
Good Agreement

Over the past several years a considerable body of evidence has accumulated, suggesting that extended radio sources are powered quasi-continuously from the nuclei of their parent galaxies. This view is supported by the recent discovery that several radio galaxies have narrow radio jets which connect their active nuclei with the large radio lobes and which often extend for several tens of kiloparsecs. Because of their presumed association with the energy transport outward from the active nuclei, radio jets are at present being intensively studied with high-resolution radio techniques.The closest galaxy known to have a radio jet is the giant elliptical M87 (e.g., Wilkinson 1974), and in this case there is a well-known optical counterpart (e.g., Curtis 1918; de Vaucouleurs, Angione and Fraser 1968), This optical jet is highly polarized (Baade 1956), implying that at least part of the emission is non-thermal. This and the good agreement between the optical and radio structure suggests that these features are closely related.

scholarly journals Radio-Mode Feedback in Massive Galaxies at Redshift 0 < z < 1

2009 ◽  
Vol 5 (S267) ◽  
pp. 377-382
Author(s):  
Elaine M. Sadler ◽  
Scott M. Croom ◽  
John H. Y. Ching ◽  
Helen M. Johnston ◽  
Russell D. Cannon ◽  
...  
Keyword(s):  
Black Hole ◽  
Stellar Population ◽  
Radio Sources ◽  
Early Type ◽  
Massive Galaxies ◽  
Radio Jets ◽  
Black Hole Accretion ◽  
Large Observational Study ◽  
Ir Signature ◽  
Hole Accretion

AbstractWe have carried out a large observational study of the radio luminosities, stellar populations, and environments of massive galaxies over the redshift range 0 < z < 1. Radio jets powered by an accreting central black hole are common in massive galaxies, and there is a large class of “optically quiet AGN,” with radio emission but no optical/IR signature of black-hole accretion. The central black holes in these galaxies are probably accreting in a radiatively inefficient mode, and our results suggest that “radio-mode feedback” as described by Croton et al. is likely to occur in all masssive early-type galaxies at z < 0.8. While it appears that radio-loud AGN occur episodically in all massive early-type galaxies, we also identify a sub-population of galaxies with powerful radio sources and a prominent younger (~ 108 yr) stellar population that may have undergone recent mergers.

scholarly journals Gravitation and Jet Induced Velocities in the Narrow Line Region of Active Galaxies

1989 ◽  
Vol 8 ◽  
pp. 423-427 ◽  
Author(s):  
Mark Whittle
Keyword(s):  
Active Galaxies ◽  
Basic Question ◽  
Radio Sources ◽  
Narrow Line ◽  
Radio Luminosity ◽  
Natural Explanation ◽  
Radio Jets ◽  
Line Region ◽  
Ngc 1068 ◽  
Narrow Line Region

The basic question I want to address is : “What mechanism or mechanisms accelerate the gas in the narrow line region of active galaxies, yielding the observed profile shapes.” At the present time there is no generally accepted answer to this question. Part of the problem dates back to the first few Seyferts that were discovered which, in retrospect, seem to have had anomalously broad lines. For example NGC 1068, MKN 3, and MKN 78 have [OIII] λ 5007 FWHM ~ 1000 km s-1, which is clearly greater than anything associated with a normal galaxy velocity fields. An obvious implication was that these high velocities were in some way related to the activity. This view was reinforced by the discovery of a correlation between [OIII] FWHM and non-thermal radio luminosity (Wilson and Willis 1981). When many radio sources were found to have linear double or triple morphology (e.g. Ulvestad and Wilson 1984a,b), a natural explanation seemed to be outflowing radio jets which stir up the narrow line region and thus generate the correlation between line width and radio luminosity.

Environmental dependence of radio galaxy populations

2018 ◽  
Vol 14 (A30) ◽  
pp. 82-85
Author(s):  
Stanislav S. Shabala
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Radio Sources ◽  
Dynamical Models ◽  
Feedback Environment ◽  
Large Samples ◽  
Radio Jets ◽  
Duty Cycles ◽  
Galaxy Populations ◽  
Environmental Dependence

AbstractSensitive continuum surveys with next-generation interferometers will characterise large samples of radio sources at epochs during which cosmological models predict feedback from radio jets to play an important role in galaxy evolution. Dynamical models of radio sources provide a framework for deriving from observations the radio jet duty cycles and energetics, and hence the energy budget available for feedback. Environment plays a crucial role in determining observable radio source properties, and I briefly summarise recent efforts to combine galaxy formation and jet models in a self-consistent framework. Galaxy clustering estimates from deep optical and NIR observations will provide environment measures needed to interpret the observed radio populations.

scholarly journals Monthly VLBI Monitoring of Selected Gamma-Bright Quasars

1998 ◽  
Vol 164 ◽  
pp. 43-44 ◽  
Author(s):  
S. Britzen ◽  
A. Witzel ◽  
T.P. Krichbaum ◽  
J. Roland ◽  
S.J. Wagner
Keyword(s):  
Structural Changes ◽  
Gamma Ray ◽  
High Time Resolution ◽  
Radio Sources ◽  
High Frequencies ◽  
Geodetic Vlbi ◽  
High Energies ◽  
The Past ◽  
Curved Trajectories ◽  
Moving Jet

AbstractIn the past few years EGRET observations of extragalactic radio sources demonstrated the presence of blazars at high energies and supplied informations about their enormous luminosities. Questions arose whether outbursts at these high frequencies can be linked to structural changes in the radio regime and the need for VLBI monitoring became obvious. In the past two decades geodetic VLBI measurements gathered this kind of data.We analyzed λ =3.6 cm observations with high time-resolution (up to once a month) from the geodetic IRIS campaigns for the γ-ray active quasars PKS 0420-014 and PKS 0528+134. In both sources superluminally moving jet components could be traced over time periods of several years on curved trajectories. Both sources exhibit component ejections preceding the time of an observed gamma-ray flaring.

Optical spectroscopy of radio jets in 3C 31, 3C 75, 3C 83.1B, and 3C 465

1986 ◽  
Vol 64 (4) ◽  
pp. 369-372 ◽  
Author(s):  
Christopher P. O'Dea ◽  
Frazer N. Owen ◽  
William C. Keel
Keyword(s):  
Optical Spectroscopy ◽  
External Medium ◽  
Line Emission ◽  
Radio Sources ◽  
Ionized Gas ◽  
Radio Jets ◽  
Upper Limits ◽  
The Galaxy ◽  
Lower Limits ◽  
Total Velocity

We present preliminary results of optical spectroscopy of four radio galaxies with jets (3C 75, 3C 465, 3C 31, and 3C 83. 1B (NGC 1265)). We examined selected regions in and around the radio jets for evidence of the interaction of the jets with their external medium (e.g., entrainment or bending through collision with clouds). We searched for the emission lines expected from ionized gas at a temperature of T ~ 104 K (e.g., Hα and [NII]) as well as those expected at higher temperatures (T ~ 106 K, Fe X (λ6374) and Fe XIV (λ5303)).We found no extranuclear emission in the regions searched in 3C 75, 3C 465, and 3C 83.1B. Assuming values for the pressure in the environment of the radio sources, we found the upper limits to the line emission correspond to model-dependent lower limits to the temperature in the range T ≥ 1.5–3 × 106 K and upper limits to the electron density in the range ne ≤ 5 × 10−2−5 × 10−3 cm−3.In 3C 31, we detected extended Hα and [NII] emission that is peaked on the nucleus and exhibits a velocity gradient. The [NII] emission has a total velocity width of ~800 km∙s−1. It is not yet clear whether any of this emission is associated with the jet (e.g., entrained gas) or whether it is associated with a known dust lane in the galaxy NGC 383.

scholarly journals Through the kaleidoscope: star formation the host galaxies of radio-AGN

2013 ◽  
Vol 9 (S304) ◽  
pp. 323-326
Author(s):  
Marios Karouzos ◽  
Myungshin Im ◽  
Markos Trichas ◽  
Tomo Goto ◽  
Matt Malkan ◽  
...  
Keyword(s):  
Star Formation ◽  
Feedback Mechanism ◽  
Host Galaxy ◽  
Radio Sources ◽  
Radio Luminosity ◽  
Powerful Radio ◽  
Host Galaxies ◽  
Radio Jets ◽  
The North ◽  
Multi Wavelength

AbstractThere exist strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. A rich multi-wavelength dataset is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope. We investigate the star-formation properties of the host galaxies of radio-AGN together with the radio feedback mechanism, potentially responsible for the eventual quenching of star formation. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while offering evidence supporting a “maintenance” type of feedback from powerful radio-jets.

Radio jets in classical double radio sources with strong cores

1984 ◽  
Vol 283 ◽  
pp. 515 ◽  
Author(s):  
J. O. Burns ◽  
J. P. Basart ◽  
D. S. de Young ◽  
D. C. Ghiglia
Keyword(s):  
Radio Sources ◽  
Radio Jets
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