Hydrodynamical backflow in X-shaped radio galaxy PKS 2014−55

Cotton, W. D.; Thorat, K.; Condon, J. J.; Frank, B. S.; Józsa, G. I. G.; White, Sarah V.; Deane, Roger; Oozeer, Nadeem; Atemkeng, Marcellin; Bester, L.; Fanaroff, B. L.; Kupa, R.S.; Smirnov, O.; Mauch, T.; Krishnan, V.; Camilo, F.

doi:10.1093/mnras/staa1240

Cited by 70 publications

(73 citation statements)

References 44 publications

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“…In a recent work presenting MeerKAT observations, Cotton et al (2020) have shown hydrodynamical backflow in action in a GRG in common with our sample (PKS 2014-55; see Bruni et al 2020), underlying how the host galaxy PA, and thus its interstellar medium, can originate the deflection when they are tilted with respect to the jet axis. From a simple bidimensional Gaussian fit of the optical emission from the Pan-STARRS image, we estimated a PA of 31 • ± 7 • for the host galaxy major axis, consistent with the one measured for the southern jet axis (∼34 • ): this alignment between jet and host galaxy major axis does not support the mentioned backflow scenario.…”

Section: J0318+684supporting

confidence: 73%

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: J0318+684supporting

confidence: 73%

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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“…However, based on the currently accepted value of H 0 ∼ 70 km s −1 Mpc −1 , RGs larger than 0.7 Mpc are now also considered GRGs. In the compilation of GRGs by Kużmicz et al (2018), the EMU-PS area contains only a single GRG, namely PKS 2014−558, first mentioned as a GRG by Jones & McAdam (1992) and recently studied in detail by Cotton et al (2020).…”

Section: Giant Radio Galaxiesmentioning

confidence: 99%

The Evolutionary Map of the Universe pilot survey

Norris

Marvil

Collier

et al. 2021

Publ. Astron. Soc. Aust.

115

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We present the data and initial results from the first pilot survey of the Evolutionary Map of the Universe (EMU), observed at 944 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The survey covers $270 \,\mathrm{deg}^2$ of an area covered by the Dark Energy Survey, reaching a depth of 25–30 $\mu\mathrm{Jy\ beam}^{-1}$ rms at a spatial resolution of $\sim$ 11–18 arcsec, resulting in a catalogue of $\sim$ 220 000 sources, of which $\sim$ 180 000 are single-component sources. Here we present the catalogue of single-component sources, together with (where available) optical and infrared cross-identifications, classifications, and redshifts. This survey explores a new region of parameter space compared to previous surveys. Specifically, the EMU Pilot Survey has a high density of sources, and also a high sensitivity to low surface brightness emission. These properties result in the detection of types of sources that were rarely seen in or absent from previous surveys. We present some of these new results here.

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“…This would suggest that the central black hole and its accretion disk underwent a significant precession recently, possibly during the current episode of radio-AGN activity, whereby the jet direction changed by ∼50 • in the plane of the sky. It is quite possible that such a precession may have been triggered by the ongoing galaxy interactions, and is the mechanism (of the many mechanisms proposed to explain the X-shape in radio galaxies; Cotton et al 2020;Hardcastle et al 2019) responsible for the observed X-shape of 3C 433.…”

Section: Hα In the Host Galaxy Of 3c 433mentioning

confidence: 99%

Disc galaxy resolved in H I absorption against the radio lobe of 3C 433: Case study for future surveys

Murthy

Morganti

Emonts

et al. 2020

A&A

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The neutral atomic gas content of galaxies is usually studied in the H I 21 cm emission line of hydrogen. However, as we go to higher redshifts, owing to the weak strength of the transition, we need very deep integrations to detect H I emission. The H I absorption does not suffer from this dependence on distance as long as there is a sufficiently bright radio source to provide the background continuum. However, resolved H I absorption studies of galaxies are rare. We report one such rare study of resolved H I absorption against the radio galaxy 3C 433 at z = 0.101, detected with the Very Large Array. The absorption was known from single-dish observations, but owing to the higher spatial resolution of our data, we find that the absorber is located against the southern lobe of the radio galaxy. The resolved kinematics shows that the absorber has regular kinematics with an H I mass ≲3.4 × 108 M⊙ for Tspin = 100 K. We also present deep optical continuum observations and Hα observations from the Gran Telescopio CANARIAS (GTC), which reveal that the absorber is likely to be a faint disc galaxy in the same environment as 3C 433, with a stellar mass of ∼1010 M⊙ and a star-formation rate of 0.15 M⊙ yr−1 or less. Considering its H I mass, H I column density, stellar mass, and star-formation rate, this galaxy lies well below the main sequence of star forming galaxies. Its H I mass is lower than the galaxies studied in H I emission at z ∼ 0.1. Our GTC imaging has revealed, furthermore, interesting alignments between Hα and radio synchrotron emission in the H I companion and in the host galaxy of the active galactic nucleus as well as in the circumgalactic medium in between. This suggests that the shock ionization of gas by the propagating radio source may happen across a scale spanning many tens of kpc. Overall, our work supports the potential of studying the H I content in galaxies via absorption in the case of a fortuitous alignment with an extended radio continuum source. This approach may allow us to trace galaxies with low H I masses which would otherwise be missed by deep H I emission surveys. In conjunction with the deep all-sky optical surveys, the current and forthcoming blind H I surveys with the Square Kilometre Array (SKA) pathfinder facilities will be able to detect many such systems, though they may not be able to resolve the H I absorption spatially. Phase 1 of the SKA, with its sub-arcsecond resolution and high sensitivity, will be all the more able to resolve the absorption in such systems.

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Hydrodynamical backflow in X-shaped radio galaxy PKS 2014−55

Cited by 70 publications

References 44 publications

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

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

The Evolutionary Map of the Universe pilot survey

Disc galaxy resolved in H I absorption against the radio lobe of 3C 433: Case study for future surveys

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Hydrodynamical backflow in X-shaped radio galaxy PKS 2014−55

Cited by 70 publications

References 44 publications

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

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

The Evolutionary Map of the Universe pilot survey

Disc galaxy resolved in H I absorption against the radio lobe of 3C 433: Case study for future surveys

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Product

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Disc galaxy resolved in H I absorption against the radio lobe of 3C 433: Case study for future surveys