Constraining the Evolution of Young Radio-Loud AGN

Snellen, I. A. G.; Mack, K.‐H.; Schilizzi, R. T.; Tschager, W.

doi:10.1071/as02041

Cited by 28 publications

(30 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Readhead et al (1996) proposed an evolutionary scheme unifying three classes of objects: compact symmetric objects (CSOs), MSOs, and LSOs. Snellen et al (1999Snellen et al ( , 2000Snellen et al ( , 2003 discussed many aspects of the above scenario in detail. In particular they concluded that the radio luminosity of GPS/CSO objects increases as they evolve, reaches its maximum for the CSS/MSO phase, and then gradually decreases as these objects grow further to become LSOs.…”

Section: Only Fr II or Either Fr I Or Fr Ii?mentioning

confidence: 99%

Location of Weak CSS Sources on the Evolutionary Path of Radio-Loud AGN

Marecki

Spencer

Kunert

2003

Publ. – Astron. Soc. Aust

View full text Add to dashboard Cite

According to the currently accepted paradigm compact steep spectrum (CSS) sources are precursors of larger/older objects and gigahertz peaked spectrum (GPS) sources may be earlier stages of CSS sources. In this paper we confront this paradigm with the outcome of recent observations of CSS sources that are significantly weaker than those known before. In particular we claim that not all CSS sources must end up as large scale objects; if the activity phase of an AGN's central engine is shorter than the lifetime of a large scale radio source (up to ∼10 8 yr) the radio source associated with such an AGN decays earlier, e.g. at the CSS stage. We point out that a theory of thermal-viscous instabilities in the accretion disks of AGN may explain many features of radio sources at all stages of their evolution.

show abstract

Section: Only Fr II or Either Fr I Or Fr Ii?mentioning

confidence: 99%

Location of Weak CSS Sources on the Evolutionary Path of Radio-Loud AGN

Marecki

Spencer

Kunert

2003

Publ. – Astron. Soc. Aust

View full text Add to dashboard Cite

show abstract

“…Relative number statistics indicated that at a young age, radio sources must have significantly higher radio luminosities than at a later stage (O'Dea & Baum 1996;Readhead et al 1996;Fanti & Fanti 2003). This decrease in radio luminosity may be preceded by a period of luminosity increase (Snellen et al 2000b(Snellen et al , 2003.…”

Section: Introductionmentioning

confidence: 99%

VLBI observations of the CORALZ sample: young radio sources at low redshift

Vries¹,

Snellen²,

Schilizzi

et al. 2009

A&A

Self Cite

103

View full text Add to dashboard Cite

Context. Young radio-loud active galactic nuclei form an important tool to investigate the evolution of extragalactic radio sources. To study the early phases of expanding radio sources, we have constructed CORALZ, a sample of 25 compact (θ < 2 ) radio sources associated with nearby (z < 0.16) galaxies. Aims. In this paper we determine the morphologies, linear sizes, and place first constraints on the lobe expansion speeds of the sources in the sample. Methods. We observed the radio sources from the CORALZ sample with MERLIN at 1.4 GHz or 1.6 GHz, the EVN at 1.6 GHz, and global VLBI at 1.6 GHz and/or 5.0 GHz. Results. Radio maps, morphological classifications, and linear sizes are presented for all sources in the CORALZ sample. We have determined a first upper limit to the expansion velocity of one of the sources, which is remarkably low compared to the brighter GPS sources at higher redshifts, indicating a relation between radio luminosity and expansion speed, in agreement with analytical models. In addition we present further strong evidence that the spectral turnovers in GPS and CSS sources are caused by synchrotron self-absorption (SSA): the CORALZ sources are significantly offset from the well-known correlation between spectral peak frequency and angular size, but this correlation is recovered after correcting for the flux-density dependence, as predicted by SSA theory.

show abstract

“…Relative number statistics have indicated that these radio sources must be significantly more powerful at young ages, which may be preceded by a period of luminosity increase (e.g. Snellen et al 2003). Multi-epoch VLBI observations of individual Gigahertz Peaked Spectrum and Compact Symmetric Objects indicate dynamical ages in the range of a few hundred to a few thousand years (e.g.…”

Section: Introductionmentioning

confidence: 99%

T-RaMiSu: the Two-meter Radio Mini Survey

Williams

Intema

Röttgering

2012

A&A

View full text Add to dashboard Cite

We present wide area, deep, high-resolution 153 MHz GMRT observations of the NOAO Boötes field, adding to the extensive, multiwavelength data of this region. The observations, data reduction, and catalogue construction and description are described here. The seven pointings produced a final mosaic covering 30 square degrees with a resolution of 25 . The rms noise is 2 mJy beam −1 in the centre of the image, rising to 4-5 mJy beam −1 on the edges, with an average of 3 mJy beam −1 . Seventy-five per cent of the area has an rms < 4 mJy beam −1 . The extracted source catalogue contains 1289 sources detected at 5σ, of which 453 are resolved. We estimate the catalogue to be 92 per cent reliable and 95 per cent complete at an integrated flux density limit of 14 mJy. The flux densities and astrometry have been corrected for systematic errors. We calculate the differential source counts, which are in good agreement with those in the literature and provide an important step forward in quantifying the source counts at these low frequencies and low flux densities. The GMRT 153 MHz sources have been matched to the 1.4 GHz NVSS and 327 MHz WENSS catalogues and spectral indices were derived.

show abstract

Constraining the Evolution of Young Radio-Loud AGN

Cited by 28 publications

References 23 publications

Location of Weak CSS Sources on the Evolutionary Path of Radio-Loud AGN

Location of Weak CSS Sources on the Evolutionary Path of Radio-Loud AGN

VLBI observations of the CORALZ sample: young radio sources at low redshift

T-RaMiSu: the Two-meter Radio Mini Survey

Contact Info

Product

Resources

About