The Statistics and Ages of Compact Symmetric Objects

Readhead, A. C. S.; Taylor, G. B.; Xu, W.; Pearson, T. J.; Wilkinson, P. N.; Polatidis, A. G.

doi:10.1086/176996

Cited by 233 publications

(309 citation statements)

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“…CSOs are radio sources that have sizes on scales of 1 pc to 1 kpc, and are thought to be very young (≤ 10 4 yr; Readhead et al (1996); Owsianik & Conway (1998)). Moreover, because CSOs are highly confined sources, they are thought to have higher conversion efficiency of jet kinetic energy to radio luminosity.…”

Section: Discussionmentioning

confidence: 99%

VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 ATZ= 6.12

Momjian

Carilli

McGreer

2008

The Astronomical Journal

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We present 8.4 GHz VLA A-array and 1.4 GHz VLBA results on the radio continuum emission from the highest redshift radio-loud quasar known to date, the z = 6.12 QSO J1427+3312. The VLA observations show an unresolved steep spectrum source with a flux density of 250 ± 20 µJy at 8.4 GHz and a spectral index value of α 8.41.4 = −1.1. The 1.4 GHz VLBA images reveal several continuum components with a total flux density of 1.778±0.109 mJy, which is consistent with the flux density measured with the VLA at 1.4 GHz. Each of these components is resolved with sizes of a few milliarcseconds, and intrinsic brightness temperatures on the order of 10 7 to 10 8 K. The physical characteristics as revealed in these observations suggest that this QSO may be a Compact Symmetric Object, with the two dominant components seen with the VLBA, which are separated by 31 mas (174 pc) and have intrinsic sizes of ∼ 22−34pc, being the two radio lobes that are confined by the dense ISM. If indeed a CSO, then the estimated kinematic age of this radio AGN is only 10 3 yr.

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Section: Discussionmentioning

confidence: 99%

VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 ATZ= 6.12

Momjian

Carilli

McGreer

2008

The Astronomical Journal

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“…Giga-hertz peaked spectrum (GPS) and compact steep-spectrum (CSS) radio sources (of subgalactic radio size) with a doublelobed structure, which are referred to as CSOs and MSOs (compact and medium-size symmetric objects), have been suggested for several years to be the young precursors of the large size powerful radio galaxies (Fanti et al 1995;Readhead et al 1996;O'Dea & Baum 1997). Since then a considerable amount of data have been produced to shed light on their properties and to develop theoretical models about their radio evolution (e.g.…”

Section: Introductionmentioning

confidence: 99%

The B3-VLA CSS sample

Fanti

Zanichelli

et al. 2011

A&A

120

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Context. Compact steep-spectrum radio sources and giga-hertz peaked spectrum radio sources (CSS/GPS) are generally considered to be mostly young radio sources. In recent years we studied at many wavelengths a sample of these objects selected from the B3-VLA catalog: the B3-VLA CSS sample. Only ≈60% of the sources were optically identified. Aims. We aim to increase the number of optical identifications and study the properties of the host galaxies of young radio sources. Methods. We cross-correlated the CSS B3-VLA sample with the Sloan Digital Sky Survey (SDSS), DR7, and complemented the SDSS photometry with available GALEX (DR 4/5 and 6) and near-IR data from UKIRT and 2MASS. Results. We obtained new identifications and photometric redshifts for eight faint galaxies and for one quasar and two quasar candidates. Overall we have 27 galaxies with SDSS photometry in five bands, for which we derived the ultraviolet-optical spectral energy distribution (UV-O-SED). We extended our investigation to additional CSS/GPS selected from the literature. Most of the galaxies show an excess of ultra-violet (UV) radiation compared with the UV-O-SED of local radio-quiet ellipticals. We found a strong dependence of the UV excess on redshift and analyzed it assuming that it is generated either from the nucleus (hidden quasar) or from a young stellar population (YSP). We also compare the UV-O-SEDs of our CSS/GPS sources with those of a selection of large size (LSO) powerful radio sources from the literature. Conclusions. If the major process of the UV excess is caused by a YSP, our conclusion is that it is the result of the merger process that also triggered the onset of the radio source with some time delay. We do not see evidence for a major contribution from a YSP triggered by the radio sources itself.

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“…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

103

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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.

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The Statistics and Ages of Compact Symmetric Objects

Cited by 233 publications

References 0 publications

VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 ATZ= 6.12

VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 ATZ= 6.12

The B3-VLA CSS sample

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

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