Are 3C 249.1 and 3C 334 restarted quasars?

Marecki, A.

doi:10.1051/0004-6361/201220010

Cited by 5 publications

(1 citation statement)

References 36 publications

(38 reference statements)

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“…We suggest that RGZJ123300.2+060325 is a plausible example of the formation of HyMoRS through the amplification of the AGN activity, which we propose as an additional possible mechanism in this paper. This complements the central engine activity argument (activity cessation) put forward by Marecki (2012aMarecki ( , 2012b.…”

Section: Hymors As Quasarssupporting

confidence: 69%

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Kapińska

Terentev²,

Wong

et al. 2017

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Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a largescale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies (L 4.7 10 median 24=´W Hz −1 sr −1 ) at redshifts z 0.14 1.0 < < . Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high-and two as low-excitation galaxies. Two candidate HyMoRS are giant ( 1 > Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

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Section: Hymors As Quasarssupporting

confidence: 69%

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Kapińska

Terentev²,

Wong

et al. 2017

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Orientation of the cores of hybrid morphology radio sources

Ceglowski

Gawroński

Kunert-Bajraszewska

2013

A&A

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Aims. The FR I/FR II dichotomy is a much debated issue in the astrophysics of extragalactic radio sources. Study of the properties of HYbrid MOrphology Radio Sources (HYMORS) may bring crucial information and lead to a step forward in understanding the origin of FR I/FR II dichotomy. HYMORS are a rare class of double-lobed radio sources where each of the two lobes clearly exhibits a different FR morphology. This article describes follow-up high resolution VLBA observations of the five discovered by us HYMORS. The main aim of the observations was to answer the questions of whether the unusual radio morphology is connected to the orientation of objects towards the observer. Methods. The milliarcsecond-scale structures are good probes of the galactic medium, the possible asymmetries, and orientation of the central engines of the sources. We obtained the high resolution radio maps of five hybrid radio morphology objects with the VLBA at C-band and L-band. Results. The cores of all five sources have been detected at both radio bands. Two of them revealed milliarcsecond core-jet structures, the next two objects showed hints of parsec-scale jets, and the last one remained point-like at both frequencies. Conclusions. We compared properties of observed milliarcsecond structures of hybrid sources with the larger scale ones previously detected with the VLA. We find that on both scales the fluxes of their central components are similar, which may indicate the lack of additional emission in the proximity of the nucleus. This suggests that jets present on the ∼1−10 kpc scale in those objects are FR II-like. When possible, the detected core-jet structures were used for estimating the core's spatial orientation. The result is that neither the FR I-like nor the FR II-like side is preferred, which may suggest that no specific spatial orientation of HYMORS is required to explain their radio morphology. Their estimated viewing angles indicate they are unbeamed objects. The 178/151 MHz luminosity of observed HYMORS exceed the traditional FR I/FR II break luminosity, indicating they have radio powers similar to FR IIs.

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Restarted activity in the 3C 328 radio galaxy

Marecki

2021

A&A

Self Cite

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As a rule, both lobes of Fanaroff-Riley (FR) type-II radio sources are terminated with hotspots, but the 3C 328 radio galaxy is a specimen of an FR II-like object with a hotspot in only one lobe. A conceivable reason for such asymmetry is that the nucleus of 3C 328 was temporarily inactive. There was no energy transfer from it to the lobes during the period of quiescence, and so they began to fade out. However, under the assumption that the axis connecting the two lobes makes an appreciable angle with the sky plane, and hence one is considerably farther from the observer than the other, the lobes are observed at two distinct stages of evolution due to the light-travel lag. While the far-side lobe is still perceived as being of the FR II type with a hotspot, decay of the near-side lobe is already apparent. No jets are visible in the VLA images, but the VLBA observations of the inverted-spectrum core component of 3C 328 have revealed that it has a jet of a sub-arcsecond length pointing towards the lobe that shows evidence of decay. Since the jet always points to the near side, its observed orientation is in line with the scenario proposed here. The presence of the jet supports the inference that the nucleus of 3C 328 is currently active; however, given the fact that the jet is short (∼200 pc in projection), the activity must have restarted very recently. The lower and upper limits of the quiescent period length have been calculated.

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Are 3C 249.1 and 3C 334 restarted quasars?

Cited by 5 publications

References 36 publications

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Orientation of the cores of hybrid morphology radio sources

Restarted activity in the 3C 328 radio galaxy

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