The Bologna Complete Sample of Nearby Radio Sources

Giovannini, G.; Taylor, G. B.; Feretti, L.; Cotton, W. D.; Lara, L. M.; Venturi, T.

doi:10.1086/426106

Cited by 76 publications

(114 citation statements)

References 22 publications

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“…To improve our statistics, we performed a search of the literature and archive data for VLBI data of BCGs in Abell clusters that have detailed information about the cluster dynamics (X-ray emission) and radio emission at mas and arcsec resolution. To obtain an extended BCG list, we added to our complete sample the following sources: Giovannini et al 2005); -Hydra A in A780 (Taylor 1996;Wise et al 2007); -4C 26.42 in A1795 (Liuzzo et al 2009a;Salomé & Combes 2004); -3C317 in A2052 (Venturi et al 2004); -B2151+174 in A2390 (Augusto et al 2006); -PKS 2322-123 in A2597 (Morris & Fabian 2005;Taylor et al 1999): -PKS 1246-410 (NGC4696) in A3526 (Taylor et al 2006b). …”

Section: The Extended Samplementioning

confidence: 99%

“…We use as a comparison sample the Bologna Complete Sample (BCS) (Giovannini et al 2001(Giovannini et al , 2005. This sample is composed of 95 FRI radio galaxies spanning the same radio power range as our BCG sample.…”

Section: Jet Velocitiesmentioning

confidence: 99%

“…As for our sample, VLBI observations at 5 GHz and kiloparsec morphology information for most of these objects are available and presented in Liuzzo et al (2009b). Among the results from the BCS study, Giovannini et al (2005) and Liuzzo et al (2009b) found that the Notes. We report the number of BCG according to the cluster morphology and parsec-scale morphology.…”

Section: Jet Velocitiesmentioning

confidence: 99%

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Parsec-scale properties of brightest cluster galaxies

Liuzzo

Giovannini

Giroletti³

et al. 2010

A&A

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We present new VLBI observations at 5 GHz of a complete sample of brightest cluster galaxies (BCGs) in nearby Abell clusters (distance class <3). Combined with data from the literature, we provide parsec-scale information for 34 BCGs. Our analysis of the parsec-scale radio emission of BCGs and the cluster X-ray properties finds a possible dichotomy between BCGs in cool-core clusters and those in non-cool-core clusters. Among resolved sources, those in cool-core clusters tend to have two-sided parsec-scale jets, while those in less relaxed clusters have predominantly one-sided parsec-scale jets. We suggest that this difference is caused by the interplay between the jets and the surrounding medium. The one-sided structure in non-cool-core clusters may be due to Doppler boosting effects in relativistic, intrinsically symmetric jets whereas two-sided morphology in cool core clusters is probably related to the presence of heavy and mildly relativistic jets that have been decelerated on the parsec-scale. Evidence of recurrent activity is also found in BCGs in cool-core clusters.

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Section: The Extended Samplementioning

confidence: 99%

Section: Jet Velocitiesmentioning

confidence: 99%

Section: Jet Velocitiesmentioning

confidence: 99%

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Parsec-scale properties of brightest cluster galaxies

Liuzzo

Giovannini

Giroletti³

et al. 2010

A&A

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“…Moreover we re-reduced the data at 5 GHz of 1997 April 4 (Giovannini et al 2005). All data were obtained using the phase referencing mode, except for the 5 GHz data of 1997, whose quality largely improved after applying the improved source position obtained from the newer data taken using phase referencing.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

The parsec-scale properties of the radio galaxy 4C 26.42 in the dense cooling core cluster A1795

Liuzzo

Taylor

Giovannini

et al. 2009

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Aims. The aim of the present work is to study the radio emission on the parsec scale of 4C 26.42, the Brightest cluster galaxy in Abell 1795, in the framework of radiosources in a dense cool core cluster. Methods. We present Very Long Baseline Array (VLBA) observations at 1.6, 5, 8.4 and 22 GHz. We performed a spectral index and multiepoch analysis. Results. The source appears two-sided with a well defined and symmetric Z-structure at ∼5 mas from the core. The kiloparsec-scale morphology is similar to the parsec-scale structure, but reversed in PA, with symmetric 90 • bends at about 2 arcsec from the nuclear region. Comparing data obtained at 3 different epochs we derive a 3σ limit to the apparent proper motion of β a < 0.04. We suggest that the parsec-scale jets are sub-relativistic, in contrast with the high velocities found for most low-power radio galaxies. The origin of the unusual radio morphology remains a puzzle. We suggest that the identification of the parent galaxy with the central cD in a cooling cluster plays an important role in the properties and structure of the jets.

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“…on pc scales (Bridle 1982), becoming subrelativistic and diffuse on kpc scales (Giovannini et al 2005). However, in some FR I sources the structure of the jet in the kiloparsec scale appears more complicated, with an inner spine that remains relativistic and an outer shell that decelerates and becomes sub-relativistic (Canvin et al 2005); -FR II sources are more powerful than the FR I ones, with a threshold power ∼10 25 W Hz −1 sr −1 increasing with the radio galaxy luminosity (Ledlow & Owen 1996); -FR II are usually found in poor gas environments, with jets probably collimated by their helical magnetic fields (Hardcastle & Worrall 2000;Asada et al 2002;Zavala & Taylor 2005) and slightly interacting with the external gas.…”

Section: Introductionmentioning

confidence: 99%

Relativistic spine jets from Schwarzschild black holes

Méliani¹,

Sauty²,

Tsinganos³

et al. 2010

A&A

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Context. The two types of Fanaroff-Riley (FR) radio-loud galaxies, FR I and FR II, exhibit strong jets which have different properties. These differences may be associated to the central engine and/or the external medium. Aims. The AGN classification FR I and FR II can be linked to the rate of electromagnetic Poynting flux extraction from the inner corona of the central engine by the jet. The collimation results from the distribution of the total electromagnetic energy across the jet, as compared to the corresponding distribution of the thermal and gravitational energies. Methods. We use exact solutions of the fully relativistic magnetohydrodynamical (GRMHD) equations obtained by a nonlinear separation of the variables to study outflows from a Schwarzschild black hole corona. Results. A strong correlation is found between the jet features and the energetic distribution of the plasma of the inner corona, which may be related to the efficiency of the magnetic rotator. Conclusions. It is shown that observations of FR I and FR II jets may be partially constrained by our model for spine jets. The deceleration observed in FR I jets may be associated with a low magnetic efficiency of the central magnetic rotator and an important thermal confinement by the hot surrounding medium. Conversely, the strongly collimated and accelerated FR II outflows may be self-collimated by their own magnetic field because of the high efficiency of the central magnetic rotator.

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The Bologna Complete Sample of Nearby Radio Sources

Cited by 76 publications

References 22 publications

Parsec-scale properties of brightest cluster galaxies

Parsec-scale properties of brightest cluster galaxies

The parsec-scale properties of the radio galaxy 4C 26.42 in the dense cooling core cluster A1795

Relativistic spine jets from Schwarzschild black holes

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