FIRST-based survey of Compact Steep Spectrum sources, III. MERLIN and VLBI observations of subarcsecond-scale objects

Abstract

According to a generally accepted paradigm, small intrinsic sizes of Compact Steep Spectrum (CSS) radio sources are a direct consequence of their youth, but in later stages of their evolution they are believed to become large-scale sources. However, this notion was established mainly for strong CSS sources. In this series of papers we test this paradigm on 60 weaker objects selected from the VLA FIRST survey. They have 5-GHz flux densities in the range 150 < S_{5GHz} < 550 mJy and steep spectra in the range 0.365 \le ν\le 5 GHz. The present paper is focused on sources that fulfill the above criteria and have angular sizes in the range 0.2\arcsec - 1\arcsec. Observations of 19 such sources were obtained using MERLIN in "snapshot" mode at 5 GHz. They are presented along with 1.7-GHz VLBA and 5-GHz EVN follow-up snapshot observations made for the majority of them. For one of the sources in this subsample, 1123+340, a full-track 5-GHz EVN observation was also carried out. This study provides an important element to the standard theory of CSS sources, namely that in a number of them the activity of their host galaxies probably switched off quite recently and their further growth has been stopped because of that. In the case of 1123+340, the relic of a compact "dead source" is particularly well preserved by the presence of intracluster medium of the putative cluster of galaxies surrounding it. The observed overabundance of compact sources can readily be explained in the framework of the scenario of "premature" cessation of the activity of the host galaxy nucleus. It could also explain the relatively low radio flux densities of many such sources and, in a few cases, their peculiar, asymmetric morphologies. We propose a new interpretation of such asymmetries based on the light-travel time argument.

arXiv comment37 pages, 22 figures, matches the version printed in Astronomy & Astrophysics

References in corpus (17)

• The dividing line between FR I and FR II radio--galaxies
• Intermittent radio galaxies and source statistics
• A first sample of faint radio sources with virtually complete redshifts: I. Infrared images, the Hubble diagram, and the alignment effect
• 9C: A Survey of Radio Sources at 15 GHz with the Ryle Telescope
• A sample of 6C radio sources with virtually complete redshifts. II - optical spectroscopy
• Low Power Compact Radio Galaxies at High Angular Resolution
• Compact steep-spectrum sources from the S4 sample
• The B3-VLA CSS sample. II: VLBA images at 18 cm
• Deriving the Quasar Luminosity Function from Accretion Disk Instabilities
• X-ray Cluster Associated with the z=1.063 CSS Quasar 3C 186: The Jet is NOT Frustrated
• Jet propagation and the asymmetries of CSS radio sources
• On the turbulent $\alpha$-disks and the intermittent activity in AGN
• FIRST-based survey of Compact Steep Spectrum sources, II. MERLIN and VLA observations of Medium-sized Symmetric Objects
• PKS B1400-33: an unusual radio relic in a poor cluster
• The B3-Vla CSS sample. III: Evn & Merlin images at 18 cm
• Accretion Disk Instabilities, CDM models and their role in Quasar Evolution
• CSSs in a sample of B2 radio sources of intermediate strength

Cited by in corpus (13)

• Radio-loud Narrow-Line Type 1 Quasars
• A survey of Low Luminosity Compact sources and its implication for evolution of radio-loud AGNs. I. Radio data
• In search of dying radio sources in the local universe
• Samples and statistics of CSS and GPS sources
• VLBI observations of seven BL Lac objects from RGB sample
• FIRST-based survey of Compact Steep Spectrum sources, IV. Multifrequency VLBA observations of very compact objects
• A survey of Low Luminosity Compact sources and its implication for evolution of radio-loud AGNs. II. Optical analysis
• The last breath of the young gigahertz-peaked spectrum radio source PKS 1518+047
• FIRST-based survey of Compact Steep Spectrum sources, V. Milliarcsecond-scale morphology of CSS objects
• Parsec-scale properties of steep and flat spectrum extragalactic radio sources from a VLBA survey of a complete north polar cap sample
• Deep Extragalactic VLBI-Optical Survey (DEVOS) II. Efficient VLBI detection of SDSS quasars
• The transition from quasar radio-loud to radio-quiet state in the framework of the black hole scalability hypothesis
• A survey of Low Luminosity Compact sources