A Case for Renewed Activity in the Giant Radio Galaxy J0116−473

Saripalli, L.; Subrahmanyan, R.; Shankar, N. Udaya

doi:10.1086/324600

Cited by 76 publications

(64 citation statements)

References 27 publications

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“…The majority of well-defined DDRSs, apart from two pairs of lobes, have a core. While this is the case for B 0925+420, B 1240+389, B 1450+333 (Schoenmakers et al 2000a), B 1834+620 (Schoenmakers et al 2000b), J0116−473 (Saripalli et al 2002), and B 1545−321 (Saripalli et al 2003), we have found no core in B 0818+214. This could mean that the energy transport from the core has ceased, although, taking into account that at least one hotspot is still visible, this should have happened very recently.…”

Section: Discussioncontrasting

confidence: 82%

“…Because the lifetimes of relic lobes are that long, it is plausible that a new active phase of a galaxy may begin before the old lobes have faded out completely, so that its radio images show components resulting from both current and past active periods. The signature of such a renewed activity is most convincing if a large, double-lobed relic structure straddles a pair of young lobes giving rise to the so-called double-double radio source (DDRS) (Lara et al 1999;Schoenmakers et al 2000a,b;Saripalli et al 2002Saripalli et al , 2003Saikia et al 2006) or even triple double (Brocksopp et al 2007). DDRSs are almost entirely identified with galaxies; an exception -quasar J0935+0204 (4C 02.27) -has been found by Jamrozy et al (2009)…”

Section: Introductionmentioning

confidence: 99%

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Evidence of a double-double morphology in B 0818+214

Marecki¹,

Szablewski²

2009

A&A

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The so-called double-double structure in radio sources is the most conspicuous signature of their restarted activity. Observations indicate that in the majority of double-double radio sources (DDRS), the span of the radio lobes is larger than 0.7 Mpc. This lower limit is also suggested by theory. However, it seemed likely that the apparent core of B 0818+214, a radio galaxy with an overall linear size of its radio structure below that limit, could harbour a compact double well aligned with the outer lobes so that the whole object would fulfil the criteria of a DDRS. Here, we present evidence that the central component of B 0818+214, when magnified through the EVN+MERLIN 18-cm observations, shows two FR II-like lobes. As the separation of the inner lobes is not greater than 5.7 kpc, they are immersed in the ISM of the host galaxy. This circumstance is the likely reason why the inner double has become visible, despite the predictions of the theory according to which B 0818+214 as a whole is too small for a new double to develop inside the cocoon inflated during the previous active phase. Moreover, we speculate that its host galaxy is not active at the moment and so the inner double may be in the coasting phase often observed in other medium-sized symmetric objects with intermittent activity. It could be, therefore, that two different mechanisms of accretion disk instabilities, ionisation and radiation-pressure driven, may be independently responsible for triggering active phases, manifesting as the outer and the inner doubles, respectively.

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Section: Discussioncontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Evidence of a double-double morphology in B 0818+214

Marecki¹,

Szablewski²

2009

A&A

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“…Less severe misalignments, but on much larger scales, and hence not likely to be affected by such projection effects, are present in other sources. Examples include the giant radio galaxy J0116− 473 (Saripalli, Subrahmanyan & Udaya Shankar 2002), J1453+3309 (Konar et al 2006) and 3C 293 (Evans et al 1999).…”

Section: Rapid Jet Reorientation Modelsmentioning

confidence: 99%

“…In some rare cases, an additional inner pair (or pairs) of radio lobes is observed, roughly aligned with the outer, presumably older, lobe pair. These, so called, "double-double" radio galaxies are believed to be examples of restarted nuclear activity (Lara et al 1999;Schoenmakers et al 2000;Saripalli, Subrahmanyan & Udaya Shankar 2002;Konar et al 2006), in which the new jet pair broadly retains its alignment with the older jets. In one scenario, the interruption in the jet activity is attributed to the disruption of the accretion disk due to the inspiral of a second supermassive black hole through the disk surrounding the larger one (Liu et al 2003).…”

mentioning

confidence: 99%

On the origin of X-shaped radio galaxies

Gopal-Krishna

Biermann

Gergely

et al. 2012

Res. Astron. Astrophys.

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After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology (XRGs) we propose a generalized model, based on the jet-shell interaction and spin-flip hypotheses. The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorientations, presumably from the spin-flips of central engines following the mergers of pairs of galaxies, each of which contains a supermassive black hole (SMBH). We confront these models with a number of key observations and thus argue that none of the models is capable of explaining the entire range of salient observational properties of XRGs, although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable. We then propose here a new scenario which also involves galactic mergers but would allow the spin of the central engine to maintain its direction. Motivated by the detailed multi-band observations of the nearest radio galaxy, Centaurus A, this new model emphasizes the role of interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets, occasionally giving rise to an X-shaped radio structure. Although each of the models is likely to be relevant to a subset of XRGs, the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.

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“…We suggest instead to reserve the term renewed source to indicate the case in which the new and the fossil components are roughly comparable in luminosity, as in the case of the doubledouble radio sources (Schoenmakers et al 2000;Saripalli et al 2002Saripalli et al , 2003.…”

Section: Introductionmentioning

confidence: 99%

Dying radio galaxies in clusters

Murgia

Parma

Mack

et al. 2011

A&A

153

275

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Aims. We present a study of five "dying" nearby (z ≤ 0.2) radio galaxies belonging to both the WENSS minisurvey and the B2 bright catalogs WNB1734+6407, WNB1829+6911, WNB1851+5707, B2 0120+33, and B2 1610+29. Methods. These sources have been selected on the basis of their extremely steep broad-band radio spectra, which strongly indicates that either these objects belong to the rare class of dying radio galaxies or we are observing "fossil" radio plasma remaining from a previous instance of nuclear activity. We derive the relative duration of the dying phase from the fit of a synchrotron radiative model to the radio spectra of the sources.Results. The modeling of the integrated spectra and the deep spectral index images obtained with the VLA confirmed that in these sources the central engine has ceased to be active for a significant fraction of their lifetime, although their extended lobes have not yet completely faded away. We found that WNB1851+5707 is in reality composed of two distinct dying galaxies, which appear blended together as a single source in the WENSS. In the cases of WNB1829+6911 and B2 0120+33, the fossil radio lobes are seen in conjunction with a currently active core. A very faint core is also detected in a MERLIN image of WNB1851+5707a, one of the two dying sources composing WNB1851+5707. We found that all sources in our sample are located (at least in projection) at the center of an X-ray emitting cluster. Conclusions. Our results suggest that the duration of the dying phase for a radio source in a cluster can be significantly higher than that of a radio galaxy in the field, although no firm conclusions can be drawn because of the small number statistics involved. The simplest interpretation of the tendency for dying galaxies to be found in clusters is that the low-frequency radio emission from the fading radio lobes lasts longer if their expansion is somewhat reduced or even stopped. Another possibility is that the occurrence of dying sources is higher in galaxy clusters. We argue that radio sources in dense environments, such as the center of cooling core clusters, may have a peculiar accretion mode which results in a bursting duty cycle sequence of active and quiescent periods. This result could have important implications for theories of the life cycles of radio sources and AGN feedback in clusters of galaxies but awaits confirmation from future observations of larger, statistically significant, samples of objects.

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A Case for Renewed Activity in the Giant Radio Galaxy J0116−473

Cited by 76 publications

References 27 publications

Evidence of a double-double morphology in B 0818+214

Evidence of a double-double morphology in B 0818+214

On the origin of X-shaped radio galaxies

Dying radio galaxies in clusters

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