The asymmetric radio structure and record jet of giant quasar 4C 34.47

Hocuk, S.; Barthel, P. D.

doi:10.1051/0004-6361/201015030

Cited by 16 publications

(10 citation statements)

References 57 publications

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“…Similarly, another source showed a symmetrical, faint emission on a different axis with respect to the jet one, consistent with relic lobes from a previous radio phase or jet precession (J1153.9+5848). Finally, for 4C +34.47, already showing two radio phases from our previous studies, we could confirm a discontinuous, knotty jet at a frequency an order of magnitude lower than the previous study from Hocuk & Barthel (2010). This is suggestive of either an intermittent radio activity, or of a plasma recollimation/expansion along the jet.…”

Section: S U M M a Ry A N D C O N C L U S I O N Ssupporting

confidence: 67%

“…These properties were not revealed at the lower resolution of the TGSS image discussed in Bruni et al (2020). Hocuk & Barthel (2010) first revealed the knotty structure of the southern jet from VLA observations at 1.4 GHz and 5 GHz, and also provided an estimate of the jet angle to line of sight. On the basis of the jet/counter-jet flux density ratio, and the jet bulk velocity, they infer a jet axis angle within 57 • from the line of sight.…”

Section: C +3447mentioning

confidence: 98%

See 1 more Smart Citation

Hard X-ray selected giant radio galaxies – III. The LOFAR view

Bruni

Brienza

Panessa

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Giant radio galaxies (GRGs), with extended structures reaching hundreds of kpc, are among the most spectacular examples of ejection of relativistic plasma from supermassive black holes. In this work, third of a series, we present LOw Frequency ARray (LOFAR) images at 144 MHz, collected in the framework of the LOFAR Two-metre Sky Survey Data Release 2 (LoTSS DR2), for nine sources extracted from our sample of hard X-ray selected GRGs (HXGRG, i.e. from INTEGRAL/IBIS and Swift/BAT catalogues at >20 keV). Thanks to the resolution and sensitivity of LoTSS, we could probe the complex morphology of these GRGs, unveiling cases with diffuse (Mpc-scale) remnant emission, presence of faint off-axis wings, or a misaligned inner jet. In particular, for one source (B2 1144+35B), we could clearly detect a ∼300 kpc wide off-axis emission, in addition to an inner jet which orientation is not aligned with the lobes axis. For another source (J1153.9+5848) a structure consistent with jet precession was revealed, appearing as an X-shaped morphology with relic lobes having an extension larger than the present ones, and with a different axis orientation. From an environment analysis, we found 2 sources showing an overdensity of cosmological neighbours, and a correspondent association with a galaxy cluster from catalogues. Finally, a comparison with radio-selected GRGs from LoTSS DR1 suggested that, on average, HXGRG can grow to larger extents. These results highlight the importance of deep low-frequency observations to probe the evolution of radio galaxies, and ultimately estimate the duty cycle of their jets.

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Section: S U M M a Ry A N D C O N C L U S I O N Ssupporting

confidence: 67%

Section: C +3447mentioning

confidence: 98%

Hard X-ray selected giant radio galaxies – III. The LOFAR view

Bruni

Brienza

Panessa

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…A2, top-right panel). Hocuk & Barthel (2010), through detailed VLA observations, detected a one-sided jet in the inner kpc, analogously to 4C +63.22. An estimate of the viewing angle from the jet/counterjet emission ratio and kinematic arguments led to values <30°.…”

Section: Images From Surveys and The Literaturementioning

confidence: 86%

“…The optical clas-sification of this source's core supports a line of sight close to the jet axis (Seyfert 1). Also for this source, an estimate of the lobe magnetic field as reported by Ishwara-Chandra & Saikia (1999) allows a rough estimate of the Mpc lobe radiative age as done for the case of IGR J14488-4008 and B3 0309+411B: in this case we also assume a spectral break above 1 GHz as suggested by the steep spectral index measured by Hocuk & Barthel (2010). The estimated age is below 11 Myr, again at odds with the finding of Bruni et al (2019) who reported a GPS core in this source, and suggested a recent reactivation of the jet.…”

Section: Images From Surveys and The Literaturementioning

confidence: 99%

Hard X-ray selected giant radio galaxies – II. Morphological evidence of restarted radio activity

Bruni

Panessa

Bassani³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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About 6% of Radio Galaxies (RG) can reach linear sizes larger than 0.7 Mpc, and are then classified as Giant Radio Galaxies (GRG). The conditions that make possible the formation of such big structures is still not clear -either core accretion properties or environmental factors. Recent studies have shown that GRG can be up to four times more abundant in hard X-ray selected (i.e. from INTEGRAL/IBIS and Swift/BAT at >20 keV) RG samples. Moreover, a high fraction of young radio sources found in their cores suggests a recently restarted activity, as suggested from the discrepancy between the measured jet and lobes power, with respect to the one expected from core X-ray luminosity. Here we present a radio morphological study of a sample of 15 hard X-ray selected GRG, discussing low-frequency images from our GMRT campaign complemented with others from the literature: among them, 7/15 show evidence of restarted radio activity either in the form of double-double/X-shaped morphology, or as a cocoon emission embedding more recent jets. This, together with the objects from this sample already found hosting a young radio source in their core, suggests that at least 13 over 15 of these hard X-ray selected GRG show features which are consistent with the possibility of restarted radio activity.

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“…Results usually rely on indirect methods and are therefore often debated. The regions near AGN are also generally obscured (Spoon et al 2007;Hocuk & Barthel 2010). Predictions based on models and numerical simulations can aid observations to further our understanding of star formation.…”

Section: Introductionmentioning

confidence: 99%

Star formation near an obscured AGN

Hocuk

Spaans

2011

A&A

Self Cite

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The conditions that affect the formation of stars in radiatively and mechanically active environments are quite different from the conditions that apply to our local interstellar neighborhood. In these galactic environments, a variety of feedback processes can play a significant role in shaping the initial mass function (IMF). Here, we present a numerical study on the effects of an accreting black hole and the influence of nearby massive stars to a collapsing, 800 M , molecular cloud at 10 pc distance from the black hole. Our work focusses on the star-forming ISM in the centers of (ultra-)luminous infrared galaxies ((U)LIRGS). We therefore assume that this region is enshrouded by gas and dust and that most of the UV and soft X-ray radiation from the broad line region (BLR) is attenuated along the line of sight to the model cloud. We then parametrize and study radiative feedback effects of hard X-rays emanating from the black hole BLR, increased cosmic ray rates caused by supernovae in starbursts, and strong UV radiation produced by nearby massive stars. We also investigate the importance of shear from the supermassive, 10 6 −10 8 M , black hole as the star-forming cloud orbits around it. A grid of 42 models is created and calculated with the hydrodynamical code FLASH. We find that thermal pressure from X-rays compresses the cloud, which induces a high star-formation rate early on, but reduces the overall star-formation efficiency (SFE) to about 7% through gas depletion by evaporation. We see that the turn-over mass of the IMF increases up to a factor of 2.3, M turn = 1−1.5 M , for the model with the highest X-ray flux (160 erg s −1 cm −2 ), while the high-mass slope of the IMF becomes Γ −1 (Γ Salpeter = −1.35). This results in more high-mass stars and a non-Salpeter IMF. Cosmic rays penetrate deeply into the cloud and increase the gas temperature to about 50 K for rates that are roughly 100 times Galactic and 200 K for 3000 times Galactic, which leads to a reduced formation efficiency of low-mass stars. While the shape of the mass function is preserved, high cosmic ray rates increase the average mass of stars, thereby shifting the turn-over mass to higher values, i.e., up to several solar masses. Owing to this process, the onset of star formation is also delayed. We find that UV radiation plays only a minor role. Because UV photons cannot penetrate a dense, n 10 5 cm −3 , cloud deep enough, they only affect the late time accretion by heating the medium where the cloud is embedded in. When we increase the black hole mass, for a cloud that is at 10 pc distance, the turbulence caused by shearing effects reduces the SFE slightly. Furthermore, shear weakens the effect of the other parameters on the slope of the IMF as well as the turn-over mass. The run with the most massive black hole, however, causes so much shear that the hydrodynamics is completely dominated by this effect and it severely inhibits star formation. We conclude that the IMF inside active galaxies is different from the one obtained from local...

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The asymmetric radio structure and record jet of giant quasar 4C 34.47

Cited by 16 publications

References 57 publications

Hard X-ray selected giant radio galaxies – III. The LOFAR view

Hard X-ray selected giant radio galaxies – III. The LOFAR view

Hard X-ray selected giant radio galaxies – II. Morphological evidence of restarted radio activity

Star formation near an obscured AGN

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