A Unified Framework for X-shaped Radio Galaxies

Garofalo, David; Joshi, Ravi; Yang, Xiaolong; Singh, Chandra B.; North, Max M.; Hopkins, Matthew M.

doi:10.3847/1538-4357/ab64e3

Cited by 19 publications

(20 citation statements)

References 32 publications

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“…We have seen this in this work. But while RGs with FRII jets will on average prefer less rich environments as recently shown in the literature from our model perspective (Garofalo et al, 2018;Garofalo et al, 2020b), GRGs with FRII jets will, as a result of longer transition times, tend to distribute themselves more in richer environments. Evidence for this is emerging but while this can be seen in the simple figures of this paper, tighter theoretical constraints are possible.…”

Section: Future Work and Summarysupporting

confidence: 71%

“…The fraction of accreting black holes that form stable counterrotating configurations is given by f 1/2 1 − j d /2j h where j d and j h are the angular momenta of the disk and black hole, respectively (King et al, 2005). A quantitative estimate of this is carried out by Garofalo et al (2020b) and is captured in Figure 1, showing that below a threshold black hole mass value, retrograde accretion fails to form. Retrograde accretion is as stable as prograde accretion for very massive black holes as illustrated by the blue curve approaching 0.5 at the right end of Figure 1.…”

Section: The Gap Paradigmmentioning

confidence: 99%

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The Origin and Evolution of Giant Radio Galaxies

Garofalo

2022

Front. Astron. Space Sci.

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Giant radio galaxies are arguably the least understood of jetted active galactic nuclei (AGN). We propose that radio galaxies are the product of large mergers that do not involve radio galaxies or radio quasars, such as in merging spiral galaxies, while giant radio galaxies emerge from a merger involving a parent that in the not-too-distant past harbored a radio galaxy. Predictions following from this are an upper limit to the number fraction of giant radio galaxies to radio galaxies, lower average redshift for giant radio galaxies, a higher incidence of high excitation for giant radio galaxies compared with radio galaxies, and lower average prograde black hole spin values for giant radio galaxies compared to radio galaxies and to bright radio quiet quasars.

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Section: Future Work and Summarysupporting

confidence: 71%

Section: The Gap Paradigmmentioning

confidence: 99%

The Origin and Evolution of Giant Radio Galaxies

Garofalo

2022

Front. Astron. Space Sci.

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“…These compact jets are not young or emerging AGN in the model, but objects that have experienced a rapid retrograde accreting phase and are now approaching zero spin in their black holes, so their jets are turning off. It is interesting to point out that near this boundary line are the objects that constitute X-shaped radio galaxies (Garofalo, Joshi et al 2020).…”

Section: Discussionmentioning

confidence: 98%

“…In other words, a newly born prograde accreting QSO with black hole spin of, say, 0.3 would be a radio loud rQSO while it would be a radio loud cQSO when it evolves over some tens of millions of years to a black hole spin of, say, 0.6. These radio loud FRI QSOs have already been explored in the model and have been understood to help explain the dearth of FRI quasars (Kim et al 2016;Garofalo, Joshi et al 2020). In this paper, they help us understand where to look in the model to generate expected total numbers of cQSOs and rQSOs in the radio loud regime.…”

Section: Agn Subclass Spin/orientation Timementioning

confidence: 93%

Evidence for Radio Loud to Radio Quiet Evolution from Red and Blue Quasars

Garofalo

Bishop

2020

PASP

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Recent work on red and blue quasi-stellar objects (QSOs) has identified peculiar number distributions as a function of radio loudness that we explore and attempt to explain from the perspective of a picture in which a subset of the population of active galaxies evolves from the radio loud to the radio quiet state. Because the time evolution is slowed down by an order of magnitude or more for the radio quiet phase, the numbers of red and blue QSOs approach each other at the extreme end of the radio quiet range of radio loudness with larger numbers. The rapid time evolution of most radio loud phases, instead, makes the numbers similar but lower at the far radio loud end. At the midpoint of radio loudness, instead, the differences between red and blue QSOs experience their largest values which results from accretion rapidly spinning black holes down but subsequently spinning them up more slowly. Recovering these basic features of the observations is evidence for rapid evolution away from radio loudness and slow evolution in radio quiet states.

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“…The re-orientation time scale for such a process is of the order of 10 6 − 10 7 years (Natarajan & Armitage 1999;Dennett-Thorpe et al 2002). Additionally, jet re-orientation due to spin transition of the central SMBH in a post-merger phase has also been suggested by Garofalo et al (2020).…”

Section: Introductionmentioning

confidence: 95%

Modelling X-shaped Radio Galaxies: Dynamical and Emission Signatures from the Back-flow model

Giri,

Vaidya,

Rossi

et al. 2022

Preprint

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Context. Active galactic nuclei typically show the presence of radio jets ranging from sub-kpc to Mpc scales. Some of these radio galaxies show distortion in their jets, forming tailed or winged sources. X-shaped radio galaxies are a subclass of winged sources formation mechanism of which is still unclear. Aims. The focus of this work is to understand hydro-dynamical back-flows and their role in dynamics and non-thermal emission signatures (in presence of radiative losses and diffusive shock acceleration) during the initial phase of these galaxies. Methods. We have performed relativistic MHD simulations of an under-dense jet travelling in a tri-axial ambient using a hybrid Eulerian-Lagrangian framework to incorporate effects of micro-physical processes. Results. We have demonstrated the dominant role played by pressure gradient in shaping XRGs in thermally dominated cases. We show that the prominence of the formed structure decreases as the jet deviates from the major axis of the ambient. The wing evolution is mainly governed by re-energized particles due to shocks that keep the structure active during the evolution time. The synthetic intensity maps of the radio galaxy show similarities with morphologies that are typically found in observed XRGs. This includes the cases with wider wings than the active lobes. The characteristic emission signatures in terms of its synchrotron spectra and implication of equipartition condition in age estimation are also discussed here. Additionally, we show that discrepancy of age can be attributed to mixing of different aged particle populations. Further, the effect of viewing angle on the difference of spectral index (∆α) of the active lobes and the wings shows a large variation and degenerate behaviour. We have demonstrated the role of diffusive shocks in the obtained variation and have concluded that the ∆α spread is not a dependable characteristic in determining the formation model of XRGs.

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A Unified Framework for X-shaped Radio Galaxies

Cited by 19 publications

References 32 publications

The Origin and Evolution of Giant Radio Galaxies

The Origin and Evolution of Giant Radio Galaxies

Evidence for Radio Loud to Radio Quiet Evolution from Red and Blue Quasars

Modelling X-shaped Radio Galaxies: Dynamical and Emission Signatures from the Back-flow model

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