A new sample of large angular size radio galaxies

Lara, L. M.; Giovannini, G.; Cotton, W. D.; Feretti, L.; Marcaide, J. M.; Márquez, I.; Venturi, T.

doi:10.1051/0004-6361:20035676

Cited by 34 publications

(37 citation statements)

References 49 publications

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“…Morganti et al 1993). Similarly to Lara et al (2004), we derive this parameter using S core measured at 5 GHz and S total at 1.4 GHz.…”

Section: Radio Core Propertiesmentioning

confidence: 99%

“…In the sample of Lara et al (2004) comprising of large size FRI and FRII-type sources, the authors found an excess of sources with a core power larger than expected from their total power, and considered whether the ratio of P core 5 and P core norm , i.e. that calculated from the relation of Giovannini et al (cf.…”

Section: The Core Prominence and The Orientation Indicatormentioning

confidence: 99%

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The new sample of giant radio sources

Machalski¹,

Jamrozy²

2006

A&A

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Aims. In this paper we analyse whether "giant" radio galaxies (GRGs) differ from "normal"-size galaxies (NSGs) except for the linear extent of their radio structure. Methods. We compare a number of properties of GRGs with the corresponding properties of NSGs, and analyse the statistical trends and correlations of physical parameters, homogeneously determined for the sources, with their "fundamental" parameters: the redshift, radio luminosity, and linear size. Using the Pearson partial-correlation test on the correlation between two variables in the presence of one or two other variables, we examine which correlation is the strongest.Results. The analysis clearly shows that GRGs do not form a separate class of radio sources. They most likely evolve with time from smaller sources, however under specific circumstances. Analysing properties of GRGs and NSGs together, we find that (i) the core prominence does not correlate with the total radio luminosity (as does the core power), but it anti-correlates with the surface brightness of the lobes of sources; (ii) the energy density (and possibly the internal pressure) in the lobes is independent of redshift for constant radio luminosity and size of the sources. Thus, in the analysed samples, there is no evidence for a cosmological evolution of the IGM pressure in the form p IGM ∝ (1 + z) 5 ; (iii) the equipartition magnetic-field strength, transformed into constant source luminosity and redshift, strongly correlates with the source size. We argue that this B eq -D correlation reflects a more fundamental correlation between B eq and the source age; (iv) both the rotation and depolarisation measures suggest Faraday screens local to the lobes of sources, however their geometry and the composition of intervening material cannot be determined from the global polarisation characteristics. The significant correlation between the depolarisation measure and the linear size can be explained by less dense IGM surrounding the lobes (or cocoon) of GRGs than that in the vicinity of NSGs.

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“…Morganti et al 1993). Similarly to Lara et al (2004), we derive this parameter using S core measured at 5 GHz and S total at 1.4 GHz.…”

Section: Radio Core Propertiesmentioning

confidence: 99%

Section: The Core Prominence and The Orientation Indicatormentioning

confidence: 99%

The new sample of giant radio sources

Machalski¹,

Jamrozy²

2006

A&A

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“…In the complete sample of 3CR radio sources (Laing et al 1983) around 6% of the sources are giants; there are about 100 known. Giant radio galaxies typically have radio powers below 10 26.5 W Hz −1 sr −1 , have linear sizes less than 3 Mpc, and are observed at redshifts z < 0.25, even though z < 0.5 could be assumed as an upper limit (Ishwara-Chandra & Saikia 1999;Schoenmakers et al 2000;Lara et al 2004;Saripalli et al 2005;Machalski et al 2007). The P-D diagram (Lara et al 2004;Ishwara-Chandra & Saikia 1999) shows a dearth of high luminosity GRG, as predicted by evolutionary models (Blundell et al 1999;) and a maximum GRG linear size cut-off of 3 Mpc.…”

Section: Introductionmentioning

confidence: 99%

“…Giant radio galaxies typically have radio powers below 10 26.5 W Hz −1 sr −1 , have linear sizes less than 3 Mpc, and are observed at redshifts z < 0.25, even though z < 0.5 could be assumed as an upper limit (Ishwara-Chandra & Saikia 1999;Schoenmakers et al 2000;Lara et al 2004;Saripalli et al 2005;Machalski et al 2007). The P-D diagram (Lara et al 2004;Ishwara-Chandra & Saikia 1999) shows a dearth of high luminosity GRG, as predicted by evolutionary models (Blundell et al 1999;) and a maximum GRG linear size cut-off of 3 Mpc. An estimate of the predominant process of radiative losses, obtained by separating the contributions of the inverse Compton and synchrotron losses, shows that the ratio of the estimated B CMB /B eq increases with linear size, and IC losses dominate the radiative losses in GRG (Ishwara-Chandra & Saikia 1999).…”

Section: Introductionmentioning

confidence: 99%

Low-frequency study of two giant radio galaxies: 3C 35 and 3C 223

Orrù

Murgia

Feretti

et al. 2010

A&A

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Aims. Radio galaxies with a projected linear size > ∼ 1 Mpc are classified as giant radio sources. According to the current interpretation these are old sources which have evolved in a low-density ambient medium. Because radiative losses are negligible at low frequency, extending spectral aging studies in this frequency range will allow us to determine the zero-age electron spectrum injected and then to improve the estimate of the synchrotron age of the source. Methods. We present Very Large Array images at 74 MHz and 327 MHz of two giant radio sources: 3C 35 and 3C 223. We performed a spectral study using 74, 327, 608 and 1400 GHz images. The spectral shape is estimated in different positions along the source. Results. The radio spectrum follows a power-law in the hotspots, while in the inner region of the lobe the shape of the spectrum shows a curvature at high frequencies. This steepening agrees with synchrotron aging of the emitting relativistic electrons. In order to estimate the synchrotron age of the sources, the spectra were fitted with a synchrotron model of emission. They show that 3C 35 is an old source of 143 ± 20 Myr, while 3C 223 is a younger source of 72 ± 4 Myr.

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“…We are aware that for redshift values greater than ∼0.14 (for which the linear size of the S-shaped structure is larger than 1 Mpc), the radio luminosity at 1400 MHz (log L 1400 ∼25.6) falls in the region of transition between FRI and FRII-type large radio galaxies (see Lara et al 2004). …”

Section: Extragalactic Emission From G2937+01?mentioning

confidence: 99%

Radio and X-ray properties of the source G29.37+0.1 linked to HESS J1844−030

Castelletti

Supán

Petriella

et al. 2017

A&A

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Aims. We report on the first detailed multiwavelength study of the radio source G29.37+0.1, which is an as-yet-unclassified object linked to the very-high-energy γ-emitting source HESS J1844−030. The origin of the multiwavelength emission toward G29.37+0.1 has not been clarified so far, leaving open the question about the physical relationship between these sources. Methods. Using observations carried out with the Giant Metrewave Radio Telescope (GMRT), we performed high-quality fullsynthesis imaging at 610 MHz of the field containing G29.37+0.1. The obtained data, combined with observations at 1400 MHz from The Multi-Array Galactic Plane Imaging Survey (MAGPIS) were used to investigate in detail the properties of its radio emission. Additionally, we reprocessed archival data obtained with the XMM-Newton and Chandra observatories in order to get a multiwavelength view of this unusual source. Results. The radio source G29.37+0.1 mainly consists of a bright twisted structure, named the S-shaped feature. The high sensitivity of the new GMRT observations allowed the identification of potential lobes, jets, and a nuclear central region in the S-shaped morphology of G29.37+0.1. We also highlight the detection of diffuse and low surface brightness emission enveloping the brightest emitting regions. The brightest emission in G29.37+0.1 has a radio synchrotron spectral index α=0.59±0.09. Variations in the spectral behaviour are observed across the whole radio source with the flattest spectral features in the central nuclear and jets components (α∼0.3). These results lead us to conclude that the brightest radio emission from G29.37+0.1 likely represents a newly recognized radio galaxy. The identification of optical and infrared counterparts to the emission arising from the core of G29.37+0.1 strengthens our interpretation of an extragalactic origin of the radio emission. We performed several tests to explain the physical mechanism responsible for the observed X-ray emission, which appears overlapping the northeastern part of the radio emission. Our spectral analysis demonstrated that a non-thermal origin for the X-ray emission compatible with a pulsar wind nebula is quite possible. The analysis of the spatial distribution of the CO gas revealed the presence of a complex of molecular clouds located in projection adjacent to the radio halo emission and probably interacting with it. We propose that the faint halo represents a composite supernova remnant with a pulsar powered component given by the diffuse X-ray emission superimposed along the line of sight to the radio galaxy. Further broadband observations of HESS J1844−030 are needed to disentangle its origin, although its shape and position suggest an extragalactic origin connected to G29.37+0.1.

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A new sample of large angular size radio galaxies

Cited by 34 publications

References 49 publications

The new sample of giant radio sources

The new sample of giant radio sources

Low-frequency study of two giant radio galaxies: 3C 35 and 3C 223

Radio and X-ray properties of the source G29.37+0.1 linked to HESS J1844−030

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