Vlbi Observations of 10 Compact Symmetric Object Candidates: Expansion Velocities of Hot Spots

An, Tao; Wu, Fang; Yang, Jun; Taylor, G. B.; Hong, Xiaoyu; Baan, Willem A.; Liu, Xiang; Wang, Min; Zhang, Hongbo; Wang, Weihua; Chen, Xi; Cui, Lang; Hao, Longfei; Zhu, Xinying

doi:10.1088/0067-0049/198/1/5

Cited by 56 publications

(14 citation statements)

References 62 publications

(96 reference statements)

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“…The half-width of this distribution is on the order of 1100 years. The relative excess of young sources confirms the earlier results of Gugliucci et al (2005) and An et al (2012).…”

Section: Statistics Of the Cso Samplesupporting

confidence: 89%

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The Dynamic Evolution of Young Extragalactic Radio Sources

Baan

2012

ApJ

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192

238

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The evolution of symmetric extragalactic radio sources can be characterized by four distinct growth stages of the radio luminosity versus size of the source. The interaction of the jet with the ambient medium results in the formation and evolution of sources with non-standard (flaring) morphology. In addition, cessation or restarting of the jet power and obstruction of the jet will also result in distinct morphological structures. The radio source population may thus be classified in morphological types that indicate the prevailing physical processes. Compact symmetric objects (CSOs) occupy the earliest evolutionary phase of symmetric radio sources and their dynamical behavior is fundamental for any further evolution. Analysis of CSO dynamics is presented for a sample of 24 CSOs with known redshift and hotspot separation velocity and with a large range of radio power. Observables such as radio power, separation between two hotspots, hotspot separation velocity, and kinematic age of the source are found to be generally consistent with the self-similar predictions for individual sources that reflect the varying density structure of the ambient interstellar medium. Individual sources behave different from the group as a whole. The age and size statistics confirm that a large fraction of CSOs does not evolve into extended doubles.

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“…The half-width of this distribution is on the order of 1100 years. The relative excess of young sources confirms the earlier results of Gugliucci et al (2005) and An et al (2012).…”

Section: Statistics Of the Cso Samplesupporting

confidence: 89%

“…References. The references are A12: An et al 2012;B04: Bondi et al 2004;C98: Condon et al 1998;D95: Dallacasa et al 1995;F00: Fomalont et al 2000;G06: Gallimore et al 2006;G91: Gregory & Condon 1991;G03: Giroletti et al 2003;G05: Gugliucci et al 2005 …”

Section: The Cso Data Samplementioning

confidence: 99%

The Dynamic Evolution of Young Extragalactic Radio Sources

Baan

2012

ApJ

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192

238

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“…An additional five per cent uncertainty of the flux densities were also assumed to account for the EVN amplitude calibration uncertainty (e.g. An et al 2012;Frey et al 2015). The spectral index, α, in Col. 9 is defined as S ∝ ν α , where S is the flux density and ν is the frequency.…”

Section: Resultsmentioning

confidence: 99%

On the nature of bright compact radio sources atz> 4.5

Coppejans¹,

Frey²,

Cseh³

et al. 2016

Mon. Not. R. Astron. Soc.

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High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early universe and understand galaxy evolution. Prior to this paper, 20 extragalactic radio sources at redshifts above 4.5 have been imaged with very long baseline interferometry (VLBI). Here we report on observations of an additional ten z > 4.5 sources at 1.7 and 5 GHz with the European VLBI Network (EVN), thereby increasing the number of imaged sources by 50 per cent. Combining our newly observed sources with those from the literature, we create a substantial sample of 30 z > 4.5 VLBI sources, allowing us to study the nature of these objects. Using spectral indices, variability and brightness temperatures, we conclude that of the 27 sources with sufficient information to classify, the radio emission from one source is from star formation, 13 are flat-spectrum radio quasars and 13 are steep-spectrum sources. We also argue that the steep-spectrum sources are off-axis (unbeamed) radio sources with rest-frame self-absorption peaks at or below GHz frequencies and that these sources can be classified as gigahertz peaked-spectrum (GPS) and megahertz peaked-spectrum (MPS) sources.

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“…Since their morphologies are reminiscent of the evolved double sources, they are called compact symmetric objects' ( < ∼ 1 kpc, CSOs) or medium-sized symmetric objects' ( < ∼ 1−15 kpc, MSOs). Kinematic measurements of their compact lobes suggest that these sources are younger than full-sized radio galaxies (e.g., Owsianik & Conway 1998;An et al 2012). An alternative explanation of the smaller extensions is the scenario of frustrated jets, i.e., the source is confined owing to the interaction with a dense, surrounding medium (Bicknell et al 1997;Carvalho 1998).…”

Section: Introductionmentioning

confidence: 99%

The MHz-peaked radio spectrum of the unusualγ-ray source PMN J1603–4904

Müller

Burd

Schulz

et al. 2016

A&A

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Context. The majority of bright extragalactic γ-ray sources are blazars. Only a few radio galaxies have been detected by Fermi/LAT. Recently, the GHz-peaked spectrum source PKS 1718-649 was confirmed to be γ-ray bright, providing further evidence for the existence of a population of γ-ray loud, compact radio galaxies. A spectral turnover in the radio spectrum in the MHz to GHz range is a characteristic feature of these objects, which are thought to be young due to their small linear sizes. The multiwavelength properties of the γ-ray source PMN J1603-4904 suggest that it is a member of this source class. Aims. The known radio spectrum of PMN J1603-4904 can be described by a power law above 1 GHz. Using observations from the Giant Metrewave Radio Telescope (GMRT) at 150, 325, and 610 MHz, we investigate the behavior of the spectrum at lower frequencies to search for a low-frequency turnover. Methods. Data from the TIFR GMRT Sky Survey (TGSS ADR) catalog and archival GMRT observations were used to construct the first MHz to GHz spectrum of PMN J1603-4904. Results. We detect a low-frequency turnover of the spectrum and measure the peak position at about 490 MHz (rest-frame), which, using the known relation of peak frequency and linear size, translates into a maximum linear source size of ∼1.4 kpc. Conclusions. The detection of the MHz peak indicates that PMN J1603-4904 is part of this population of radio galaxies with turnover frequencies in the MHz to GHz regime. Therefore it can be considered the second confirmed object of this kind detected in γ-rays. Establishing this γ-ray source class will help to investigate the γ-ray production sites and to test broadband emission models.

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Vlbi Observations of 10 Compact Symmetric Object Candidates: Expansion Velocities of Hot Spots

Cited by 56 publications

References 62 publications

The Dynamic Evolution of Young Extragalactic Radio Sources

The Dynamic Evolution of Young Extragalactic Radio Sources

On the nature of bright compact radio sources atz> 4.5

The MHz-peaked radio spectrum of the unusualγ-ray source PMN J1603–4904

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