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We present results of EVN observations of eleven GHz-Peaked-Spectrum (GPS) radio sources at 2.3/8.4 GHz. These sources are from the classical ''bright'' GPS source samples with peak flux densities $>$ 0.2 Jy and spectral indices $\alpha <…

Astrophysics · Physics 2007-05-23 L. Xiang , D. Dallacasa , P. Cassaro , D. Jiang , C. Reynolds

Compact Symmetric Objects (CSOs) are young radio galaxies whose jet axes lie close to the plane of the sky, and whose appearance is therefore not dominated by relativistic beaming effects. The small linear sizes of CSOs make them valuable…

Astrophysics · Physics 2009-10-31 A. B. Peck , G. B. Taylor , C. D. Fassnacht , A. C. S. Readhead , R. C. Vermeulen

Global VLBI observations at 5 GHz have been performed to study the source morphology in 10 compact steep-spectrum (CSS) sources selected from the Peacock & Wall catalogue with the aim of finding asymmetric structures produced by the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 D. Dallacasa , M. Orienti , C. Fanti , R. Fanti , C. Stanghellini

We have analysed VSOP (VLBI Space Observatory Programme) data at 5 GHz and ground-based VLBI (Very Long Baseline Interferometry) data at 15 GHz for the GHz-Peaked Spectrum (GPS) radio galaxy 2021+614. Its morphology is consistent with it…

The measurement of proper motions in CSOs is a powerful tool to determine the dynamical evolution of the newly born extragalactic radio sources. We observed 3 CSOs with the VLBA in 2004 and in 2006 to monitor changes in their structure and…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Carlo Stanghellini , Daniele Dallacasa , Tiziana Venturi , An Tao , Hong Xiao-Yu

Compact symmetric objects (CSOs) are thought to be short-lived radio sources with two lobes of emission that are separated by less than a kpc in projection. However, studies of such systems at high redshift is challenging due to the limited…

Astrophysics of Galaxies · Physics 2025-10-10 J. P. McKean , C. Spingola , D. M. Powell , S. Vegetti

We present the results of the first X-ray study of a sample of 16 young radio sources classified as Compact Symmetric Objects (CSOs). We observed six of them for the first time in X-rays using {\it Chandra}, re-observed four with the…

We present the results of 5-GHz observations with the VLA A-array of a sample of candidate Compact Steep Spectrum sources (CSSs) selected from the S4 survey. We also estimate the symmetry parameters of high-luminosity CSSs selected from…

Astrophysics · Physics 2009-10-31 D. J. Saikia , S. Jeyakumar , C. J. Salter , P. Thomasson , R. E. Spencer , F. Mantovani

Double lobe radio sources associated with active galactic nuclei represent one of the longest studied groups in radio astronomy. A particular sub-group of double radio sources comprises the compact symmetric objects (CSOs). CSOs are…

High Energy Astrophysical Phenomena · Physics 2024-01-26 Andrew G. Sullivan , Roger D. Blandford , Mitchell C. Begelman , Mark Birkinshaw , Anthony C. S. Readhead

This paper addresses, for the first time, a key aspect of the phenomenology of Compact Symmetric Objects (CSOs) -- the characteristics of their radio spectra. We present a radio-spectrum description of a complete sample of high luminosity…

A small sample of 7 southern Compact Steep Spectrum (CSS) radio sources has been selected as part of the study of a larger flux-limited complete sample of radio sources. High resolution images, using the VLBI network in the southern…

We present results of multi-frequency VLBA observations of the compact symmetric object (CSO) 0402+379. The parsec-scale morphology of 0402+379 allows us to confirm it as a CSO, while VLA data clearly show the presence of kiloparsec-scale…

Astrophysics · Physics 2009-11-10 H. L. Maness , G. B. Taylor , R. T. Zavala , A. B. Peck , L. K. Pollack

We present results of multifrequency polarimetric VLBA observations of 34 compact radio sources. The observations are part of a large survey undertaken to identify CSOs Observed in the Northern Sky (COINS). Based on VLBI continuum surveys…

Astrophysics · Physics 2007-05-23 A. B. Peck , G. B. Taylor

We present results from the first intensive monitoring campaign of a sample of Compact Symmetric Objects (CSOs). We observed seven CSOs at 8.5 GHz over a period of eight months, with an average spacing between observations of 2.7 days. Our…

Astrophysics · Physics 2009-11-06 C. D. Fassnacht , G. B. Taylor

We present the results of EVN polarization observations of fourteen GHz-Peaked-Spectrum (GPS) radio sources at 5 GHz. These sources were selected from bright GPS source samples and we aimed at finding Compact Symmetric Objects (CSOs). We…

Astrophysics · Physics 2016-08-30 Liu Xiang , Cormac Reynolds , Richard Strom , Daniele Dallacasa

We examine the evolution of variously-sized radio galaxies [i.e., compact symmetric objects (CSOs), medium-size symmetric objects (MSOs), Fanaroff-Riley type II radio galaxies (FRIIs)], by comparing the relation between the hot spot size…

Astrophysics · Physics 2009-11-13 Nozomu Kawakatu , Hiroshi Nagai , Motoki Kino

GPS and CSS radio sources are the objects of choice to investigate the evolution of young radio-loud AGN. Previous investigations, mainly based on number counts and source size distributions, indicate that GPS/CSS sources decrease…

Astrophysics · Physics 2009-11-07 I. A. G. Snellen , K. -H. Mack , R. T. Schilizzi , W. Tschager

We constrain the spectral ages for two very asymmetric Compact Symmetric Objects (CSO) from the B3-VLA-CSS sample, and we investigate the role of the ambient medium potentially able to influence the individual source evolution.…

Astrophysics · Physics 2009-11-11 M. Orienti , D. Dallacasa , C. Stanghellini

We defined a sub-sample of twelve GPS sources which have not been observed with the VLBI before, from the Parkes half-Jansky sample, and carried out VLBI observations at 1.6 GHz and 5 GHz with the European VLBI Network (EVN) in 2006 and…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-25 L. Cui , X. Liu , J. Liu , H. -G. Song , Z. Ding

Positions and proper motions of Gaia sources are expressed in a reference frame that ideally should be non-rotating relative to distant extragalactic objects, coincident with the International Celestial Reference System (ICRS), and…

Instrumentation and Methods for Astrophysics · Physics 2020-05-15 Lennart Lindegren