Radio Jets In 3C Research Articles

A wide and collimated radio jet in 3C 84

AbstractI report observations of 3C84 (NGC 1275), the central galaxy of the Perseus cluster, made with an interferometric array including the orbiting radio telescope of the RadioAstron mission. The data transversely resolve the edge-brightened jet in 3C84 only 0.03 mas from the core, which is ten times closer to the central engine than was possible in previous ground-based observations. To better understand physical properties of this peculiar source, I will discuss its present properties in comparison to the past and more recent evolution in the radio band of 3C 84.

Wavelet-based decomposition and analysis of structural patterns in astronomical images

Context. Images of spatially resolved astrophysical objects contain a wealth of morphological and dynamical information, and effective extraction of this information is of paramount importance for understanding the physics and evolution of these objects. Algorithms and methods employed presently for this purpose (such as, for instance, Gaussian model fitting) often use simplified approaches for describing the structure of resolved objects. Aims. Automated (unsupervised) methods for structure decomposition and tracking of structural patterns are needed for this purpose, in order to be able to deal with the complexity of structure and large amount of data involved. Methods. A new Wavelet-based Image Segmentation and Evaluation (WISE) method is developed for multiscale decomposition, segmentation, and tracking of structural patterns in astronomical images. Results. The method is tested against simulated images of relativistic jets and applied to data from long-term monitoring of parsec- scale radio jets in 3C 273 and 3C 120. Working at its coarsest resolution, WISE reproduces exceptionally well the previous results of model fitting evaluation of the structure and kinematics in these jets. Extending the WISE structure analysis to the finer scales provides the first robust measurements of two-dimensional velocity fields in these jets and indicates that the velocity fields are likely to reflect the evolution of Kelvin-Hemlholtz instability developing the flow.

THE RESOLVED OUTFLOW FROM 3C 48

We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 10{sup 3}-10{sup 4} cm{sup –3}, the mass is ∼6 × 10{sup 6} M {sub ☉}, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow thatmore » shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow.« less

CHANDRA OBSERVATIONS OF 3C RADIO SOURCES WITH z < 0.3. II. COMPLETING THE SNAPSHOT SURVEY

We report on the second round of Chandra observations of the 3C snapshot survey developed to observe the complete sample of 3C radio sources with z<0.3 for 8 ksec each. In the first paper, we illustrated the basic data reduction and analysis procedures performed for the 30 sources of the 3C sample observed during the Chandra Cycle 9, while here, we present the data for the remaining 27 sources observed during Cycle 12. We measured the X-ray intensity of the nuclei and of any radio hotspots and jet features with associated X-ray emission. X-ray fluxes in three energy bands: soft, medium and hard for all the sources analyzed are also reported. For the stronger nuclei, we also applied the standard spectral analysis which provides the best fit values of X-ray spectral index and absorbing column density. In addition, a detailed analysis of bright X-ray nuclei that could be affected by pileup has been performed. X-ray emission was detected for all the nuclei of the radio sources in our sample except for 3C 319. Amongst the current sample, there are two compact steep spectrum radio sources; two broad line radio galaxies; and one wide angle tail radio galaxy, 3C 89, hosted in a cluster of galaxies clearly visible in our Chandra snapshot observation. In addition, we also detected soft X-ray emission arising from the galaxy cluster surrounding 3C 196.1. Finally, X-ray emission from hotspots have been found in three FR II radio sources and, in the case of 3C 459, we also report the detection of X-ray emission associated with the eastern radio lobe and as well as that cospatial with radio jets in 3C 29 and 3C 402.

Kinematics of the parsec-scale radio jet in 3C 48

We present results on the compact steep-spectrum quasar 3C 48 from observations with the VLBA, MERLIN and EVN at multiple radio frequencies. In the 1.5-GHz VLBI images, the radio jet is characterized by a series of bright knots. The active nucleus is embedded in the southernmost VLBI component A, which is further resolved into two sub-components A1 and A2 at 4.8 and 8.3 GHz. A1 shows a flat spectrum and A2 shows a steep spectrum. The most strongly polarized VLBI components are located at component C $\sim$0.25 arcsec north of the core. The polarization angles at C show gradual changes across the jet width at all observed frequencies, indicative of a gradient in the emission-weighted intrinsic polarization angle across the jet and possibly a systematic gradient in the rotation measure; moreover, the percentage of polarization increases near the curvature at C, likely consistent with the presence of a local jet-ISM interaction and/or changing magnetic-field directions. The hot spot B shows a higher rotation measure, and has no detected proper motion. These facts provide some evidence for a stationary shock in the vicinity of B. Comparison of the present VLBI observations with those made 8.43 years ago suggests a proper motion of $\beta_{app}=3.7\pm0.4 c$ for A2 to the north. The apparent superluminal motion suggests that the relativistic jet plasma moves at a velocity of $\gtrsim0.96 c$ if the jet is viewed at an inclination angle less than $20\degr$. A simple precessing jet model and a hydrodynamical isothermal jet model with helical-mode Kelvin-Helmholtz instabilities are used to fit the oscillatory jet trajectory of 3C 48 defined by the bright knots.

A relativistic model of the radio jets in 3C 296

We present new, deep 8.5-GHz VLA observations of the nearby, low-luminosity radio galaxy 3C 296 at resolutions from 0.25 to 5.5 arcsec. These show the intensity and polarization structures of the twin radio jets in detail. We also derive the spectral-index and rotation-measure distributions. We apply our intrinsically symmetrical, decelerating relativistic jet model to the new observations. An optimized model accurately fits the data in both total intensity and linear polarization. We infer that the jets are inclined by 58 deg to the line of sight. On-axis, they decelerate from a (poorly-constrained) initial velocity of 0.8c to approximately 0.4c around 5 kpc from the nucleus, the velocity thereafter remaining constant. The speed at the edge of the jet is low everywhere. The longitudinal profile of proper emissivity has three principal power-law sections and the emission is centre-brightened. Our observations rule out a globally-ordered, helical magnetic-field configuration. Instead, we model the field as random on small scales but anisotropic, with toroidal and longitudinal components only. The ratio of longitudinal to toroidal field falls with distance along the jet, qualitatively but not quantitatively as expected from flux freezing, so that the field is predominantly toroidal far from the nucleus. The toroidal component is relatively stronger at the edges of the jet. A simple adiabatic model fits the emissivity evolution only in the outer region after the jets have decelerated and recollimated; closer to the nucleus, it predicts far too steep an emissivity decline with distance. We also interpret the morphological differences between brightness enhancements (arcs) in the main and counter-jets as an effect of relativistic aberration. (Abridged)

Modeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds

In this paper we use the predicted spatial development of helical structures along an expanding jet to model observed structures and motions in the 3C 120 jet. New results of VLBI imaging of the parsec-scale radio jet in 3C 120 at 5 GHz are examined along with older long-term monitoring results at 5 GHz and older results obtained at 22 and 43 GHz. The high-frequency observations provide detailed information on motions and structure from 0.5 to 10 mas from the core and the lower frequency observations from 1 to 30 mas from the core. Proper motions of helical components associated with the pattern and of other components that move through the pattern provide estimates of flow and helical pattern speeds. Theoretical modeling of the motion and appearance of the helical pattern allows determination of sound speeds as a function of the jet viewing angle. The jet sound speed declines although probably not as fast as adiabatically. At a 12° viewing angle the most likely scenario involves a decline in jet sound speed from c/3 < aj < c/ at ~0.5 mas from the core to 0.1c < aj < 0.25c at ~25 mas from the core accompanied by some acceleration in the jet flow from Lorentz factor γ 5 to γ 7. The sound speed in the cocoon medium around the jet is less well determined but is less than the sound speed in the jet probably by a factor of 1.5-5. A largest possible viewing angle of 15° implies a jet sound speed at the upper limit of these estimates and somewhat higher flow Lorentz factors. However, jet morphology argues against viewing angles larger than 12°. At smaller viewing angles the jet sound speed is lower, and at a 6° viewing angle the jet sound speed is about a factor of 2 less, but the flow Lorentz factor is comparable. The decline in radio intensity is on the order of what would be associated with isothermal jet expansion. Knot-interknot intensity variations are greater than would be expected from adiabatic compressions associated with the helical twist, and we infer the presence of a shock along the leading edge of the helical twist in addition to shock or density structures flowing through the helical pattern. Our results imply that the macroscopic heating of the expanding jet fluid is less than the microscopic energization of the synchrotron radiating relativistic electrons.

NGC 6212, 3C 345, and Other Quasi-stellar Objects Associated with Them

It is pointed out that the Seyfert 1 galaxy NGC 6212 is surrounded by a large number of quasi-stellar objects (QSOs), including the very active and rapidly varying radio QSO 3C 345, which lies only 47 away from the center of the galaxy. There are two pairs of QSOs with the same redshifts, including 3C 345, very close to the nucleus of NGC 6212, and the very high density of the QSOs falls off rapidly with distance from that galaxy. If 3C 345 lies at the distance of NGC 6212, the proper motions in the radio jet in 3C 345, which have been studied in detail, correspond to only mildly relativistic speeds, of about 0.33c.

The Structure and Motions of the 3C 120 Radio Jet on Scales of 0.6–300 Parsecs

Results are presented from long-term very long baseline interferometry monitoring of the parsec-scale radio jet in 3C 120 at 5 and 1.7 GHz. The 5 GHz sequence includes a few early epochs at 10.7 GHz. Superluminal features are seen leaving the core at intervals of less than a year, about as often as new features could be distinguished with the 0.6 pc resolution of the observations. The underlying jet is continuous but not smooth, and the measured features are simply the bright points in the convolution of the observing beam with brightness fluctuations that occur on many scales. The velocity of different features varies, but not by more than about a factor of 2. Clear variations in the velocity of an individual feature are not seen. Some features that were observed leaving the core in the 5 GHz observations with 0.6 pc resolution are followed at 1.7 GHz with 2.4 pc resolution to projected distances in excess of 25 pc from the core. Older features up to at least 150 pc in projection from the core are still moving at superluminal apparent speeds and are therefore presumed to be relativistic. Beyond that, the data are inadequate for motion measurements. The region where the jet slows to nonrelativistic speeds has not been found. There are suggestions of stationary features, or brightening and dimming regions, through which the moving features pass. These may be locations where there is interaction with the external medium, or they may simply be the result of variations in the jet angle to the line of sight. The observation of stationary features in an otherwise moving jet reinforces the idea that the lack of motion of the knot at 4'' (2 kpc), which has been found not to be superluminal in other observations, might not actually imply that the jet has slowed by that position. The structure of the jet in the vicinity of the most likely stationary feature is suggestive of a helical pattern seen in projection. The deprojected wavelength of the pattern is very long relative to the jet radius, unlike the situation in sources such as M87 (Owen and coworkers). If the 3C 120 jet does contain a slowly moving, helical structure, then theory suggests that the jet resides in a relatively cool medium, not in a relativistically hot cocoon or lobe.

X‐Ray Emission from the Radio Jet in 3C 120

We report the discovery of X-ray emission from a radio knot at a projected distance of 25" from the nucleus of the Seyfert galaxy, 3C 120. The data were obtained with the ROSAT High Resolution Imager (HRI). Optical upper limits for the knot preclude a simple power law extension of the radio spectrum and we calculate some of the physical parameters for thermal bremsstrahlung and synchrotron self-Compton models. We conclude that no simple model is consistent with the data but if the knot contains small regions with flat spectra, these could produce the observed X-rays (via synchrotron emission) without being detected at other wavebands.

An optical study of 3C 31, 3C 66B, 3C 120, and their jets

view Abstract Citations (22) References (49) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Optical Study of 3C31 ,3C66B, 3C120 and their Jets Fraix-Burnet, D. ; Golombek, D. ; Macchetto, F. D. Abstract We present the results of BVRI CCD photometry of the radiogalaxies 3C 31, 3C 66B, and 3C 120, and V polarimetry of 3C 120. The photometry of the jet of 3C 66B definitively establishes the synchrotron nature of the optical emission. No optical counterpart of the radio counterjet in 3C 66B and of the radio jets in 3C 31 and 3C 120 is found. A rotating ring and an ionized region are present, respectively, in 3C 31 (NGC 383) and its companion galaxy NGC 382, but we find no isophotal distortions which could have revealed a gravitational interaction between the two galaxies as is the case in 3C 66B. The elliptical isophotes of 3C 120 show a slight off- centering, roughly in the direction of the radio jet, very much like 3C 66B. We find an upper limit of 20% for the polarization level of the condensations in 3C 120. Publication: The Astronomical Journal Pub Date: August 1991 DOI: 10.1086/115893 Bibcode: 1991AJ....102..562F Keywords: Astronomical Polarimetry; Emission Spectra; Radio Galaxies; Radio Jets (Astronomy); Intergalactic Media; Isophotes; Stellar Spectrophotometry; Astrophysics; PHOTOMETRY; RADIO SOURCES: GALAXIES; GALAXIES: JETS; GALAXIES: INTERACTIONS full text sources ADS | data products SIMBAD (8) NED (3)

Evidence for superluminal motion on kiloparsec scales in 3C 120

view Abstract Citations (38) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for Superluminal Motion on Kiloparsec Scales in 3C 120 Walker, R. Craig ; Walker, Mark A. ; Benson, John M. Abstract The radio jet in 3C 120 has a knot located 4" or 2h^-1^ kiloparsecs, from the core. A shift in position of the knot away from the core by 9 +/- 3 mas in 3.75 yr has been detected with the VLA. The implied angular velocity is 2.4+/-0.8 mas yr^-1^, giving an apparent linear velocity of 3.7+/-1.2h^-1^ times the speed of light for z = 0.033 and H_0_ = 100h km s^-1^ Mpc^-1^. This superluminal velocity is similar to that seen on parsec scales in the same source with VLBI. No direct method has been found to measure the velocity of the material in a radio jet. There are indirect but convincing arguments that the low-power, two-sided jets must be nonrelativistic on kiloparsec scales. For the high-power, one-sided jets, VLBI observations of superluminal motions in the inner parsecs of many are usually considered to be convincing evidence that they are relativistic on small scales. The large-scale one-sidedness, the continuity of jet structures, and depolarization asymmetries suggest that the relativistic motion continues to kiloparsec scales but the evidence is poor. The results presented here, assuming they stand the test of future observations, considerably strengthen the argument for relativistic motion on kiloparsec scales. Publication: The Astrophysical Journal Pub Date: December 1988 DOI: 10.1086/166957 Bibcode: 1988ApJ...335..668W Keywords: Extragalactic Radio Sources; Galactic Structure; Radio Jets (Astronomy); Very Large Array (Vla); Very Long Base Interferometry; Angular Velocity; Flow Velocity; Astrophysics; GALAXIES: INDIVIDUAL ALPHANUMERIC: 3C 120; GALAXIES: JETS; GALAXIES: STRUCTURE; INTERFEROMETRY; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (1) NED (1)

VLBI Observations of the Radio Jet in 3C 273

We present a new high dynamic range map of the quasar 3C 273, made from observations with a VLBI network of 12 telescopes. This new map at 18 cm wavelength has one of the highest dynamic ranges yet achieved with VLBI, and it shows the ‘jet’ extending to at least 180 milliarcsec, or 330 pc from the nucleus of the quasar. Strong limits can be placed on the brightness of any ‘counter-jet’ on kiloparsec-scales, as no emission is visible on the opposite side of the ‘core’. Combining with other VLBI, VLA and MERLIN maps shows that the jet is visible and continuous over a very large range of scales, from 1 pc to 40 kpc.

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

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.

Fluid dynamical twisting of the radio jets in 3C 449

view Abstract Citations (30) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Fluid dynamical twisting of the radio jets in 3C 449 Hardee, P. E. Abstract The jet structure of the double jets in the radio galaxy 3C 449 can be understood as resulting from helical instability of an initially cylindrically symmetric straight jet. A growing helical wave is convected out along the jets and reaches a large amplitude at the position of the radio lobes, disrupting well-directed flow. Adiabatic expansion of the thermalized jet material produces the radio lobes. The extended diffuse emission outside the present radio lobes is the remnant of earlier, more luminous jets. Conditions in the expanding inner jets required for this mechanism to operate are almost the same as those inferred by Perley et al. (1979) from their VLA observations. The jets are supersonic, with Mach number on the order of 10, and the flow velocity is about 1500 km/sec. The density of the interstellar medium in the galaxy is inferred to be about the same as the jets' density. The age of the radio source is probably less than several times 100 million years. Publication: The Astrophysical Journal Pub Date: November 1981 DOI: 10.1086/183664 Bibcode: 1981ApJ...250L...9H Keywords: Fluid Dynamics; Galactic Structure; Interstellar Matter; Jet Flow; Radio Galaxies; Radio Jets (Astronomy); Adiabatic Conditions; Flow Stability; Flow Velocity; Kelvin-Helmholtz Instability; Mach Number; Supersonic Jet Flow; Astrophysics full text sources ADS | data products NED (2)

Collimation of the radio jets in 3C 31

Observations of the radio jets in 3C 31 using the VLA show that the rates of expansion of these jets transverse to their length decrease with increasing distance from the radio core. A rapid decrease in expansion rate in the northern jet occurs where its magnetic field appears dominated by an organized circumferential component. We use the supersonic beam model of Chan and Henriksen to show that the energy of this circumferential field need only be approx.1% of the flow kinetic energy to produce the observed changes in expansion rate by an incipient magnetic pinch. If the beams in 3C 31 are described by the Chan-Henriksen model, their circumferential field strengths cannot significantly exceed their equipartition values, or pinches much stronger than those observed would result.

On the supersonic dynamics of magnetized jets of thermal gas in radio galaxies

view Abstract Citations (153) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the supersonic dynamics of magnetized jets of thermal gas in radio galaxies Chan, K. L. ; Henriksen, R. N. Abstract A stellar-wind type formulation is developed to study axisymmetric MHD jet flows in radio galaxies. When the magnetic energy is small compared to the total energy of the jet flow and the azimuthal field has a pinching configuration, similarity methods can be used to reduce the two-dimensional partial differential equations of the problem to a system of ordinary differential equations. These solutions allow some approximate analytical solutions in the outer jet region where many parameters approach their asymptotic values, but numerical methods have to be used in the inner jet region where variables change rapidly. Numerical results on the effects of a pinching external pressure and a pinching magnetic field are discussed, and the observed width of the northern radio jet in 3C 449 is fitted by each of the two pinching models. Publication: The Astrophysical Journal Pub Date: October 1980 DOI: 10.1086/158368 Bibcode: 1980ApJ...241..534C Keywords: Magnetohydrodynamic Flow; Radio Galaxies; Stellar Winds; Supersonic Jet Flow; Asymptotic Methods; Axisymmetric Flow; Partial Differential Equations; Pinch Effect; Steady Flow; Astrophysics full text sources ADS |

Structure of the magnetic field in the radio jets in 3C 31 and NGC 315

We have used the VLA to map the distributions of the total and linearly polarized radio brightness over the inner parts of the jets in the radio galaxies 3C 31 and NGC 315. In each galaxy we find that the jet on one side of the nuclear radio core has a bright base within which the organized component of the magnetic field lies predominantly parallel to the jet for several kiloparsecs. Farther from the cores, as the jets widen, their magnetic fields become predominantly perpendicular to the jet axes, and the jets become more symmetric in intensity.

A dynamical interpretation of the radio jet in 3C 31

A dynamical interpretation of the radio jet in 3C 31