Radio properties of CSSs and GPSs

Fanti, C.

doi:10.1002/asna.200811137

Cited by 59 publications

(72 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We finally note that in the 4.8 GHz HTT2007(V) and in the 2.2 and 8.3 GHz BGP2002(V) VLBI observations, J1606+3124 has a Compact Symmetric Object (CSO) structure. CSOs are characterised by unbeamed emission from their steep-spectrum radio lobes on either side of a central position, and have sizes smaller than their host galaxy (Fanti et al 1995;Fanti 2009). …”

Section: J1606+3124mentioning

confidence: 99%

“…The observed turnover (or peak) frequencies (νo) of the CSS, MPS, GPS and HFP sources are νo < 0.5 GHz, νo < 1 GHz, 1 < νo < 5 GHz and νo > 5 GHz (O'Dea 1998;Dallacasa et al 2000;Coppejans et al 2015), respectively. These sources are believed to be young (rather than confined) AGN, some of which will likely evolve into FR I and FR II radio galaxies (Begelman 1996;O'Dea 1998;Snellen et al 2000;Conway 2002; De Vries et al 2002;Murgia et al 2002;Murgia 2003;Fanti 2009;An & Baan 2012;Orienti 2016). For the nearby (z ∼ 1) CSS, MPS, GPS and HFP sources, an empirical relation exists between the rest-frame turnover frequencies (νr, where νr = νo(1 + z)) and the linear sizes of the sources (O'Dea 1998; Snellen et al 2000;Orienti & Dallacasa 2014).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

High-redshift quasars are important to study galaxy and active galactic nuclei (AGN) evolution, test cosmological models, and study supermassive black hole growth. Optical searches for high-redshift sources have been very successful, but radio searches are not hampered by dust obscuration and should be more effective at finding sources at even higher redshifts. Identifying high-redshift sources based on radio data is, however, not trivial. Here we report on new multi-frequency Giant Metrewave Radio Telescope (GMRT) observations of eight z > 4.5 sources previously studied at high angular resolution with very long baseline interferometry (VLBI). Combining these observations with those from the literature, we construct broad-band radio spectra of all 30 z > 4.5 sources that have been observed with VLBI. In the sample we found flat, steep and peaked spectra in approximately equal proportions. Despite several selection effects, we conclude that the z > 4.5 VLBI (and likely also non-VLBI) sources have diverse spectra and that only about a quarter of the sources in the sample have flat spectra. Previously, the majority of high-redshift radio sources were identified based on their ultra-steep spectra (USS). Recently a new method has been proposed to identify these objects based on their megahertz-peaked spectra (MPS). Neither method would have identified more than 18 per cent of the high-redshift sources in this sample. More effective methods are necessary to reliably identify complete samples of high-redshift sources based on radio data.

show abstract

Section: J1606+3124mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…the inner few kpc of the host galaxy. Most of them are expected to grow to large radio galaxies (Fanti 2009) although some may actually never reach this phase, either because the fueling of the AGN "engine" stops or because of a hostile ISM (Kunert-Bajraszewska et al 2006). See also de Vries et al (2009a) and de Vries (2009b), Chap.…”

Section: Introductionmentioning

confidence: 99%

Recurrent radio emission and gas supply: the radio galaxy B2 0258+35

Shulevski

Morganti

Oosterloo

et al. 2012

A&A

View full text Add to dashboard Cite

Outlined is the discovery of a very faint, diffuse, low surface-brightness (0.5 mJy beam −1 , 1.4 mJy arcmin −2 on average) structure around the radio source B2 0258+35 hosted by an HI-rich early-type galaxy (NGC 1167). Because B2 0258+35 is a young compact steep spectrum (CSS) source, the newly discovered structure could represent a remnant from an earlier stage of activity of an active galactic nucleus (AGN). We explain in detail all possibilities for triggering the radio activity in B2 0258+35 regarding gas accretion in a recurrent AGN activity framework. NGC 1167 hosts a very regular, extended and massive H I disk that has been studied in great detail. It has regular kinematics on large scales, which, together with stellar population studies of NGC 1167, exclude the possibility of a recent merger as the trigger for the current AGN activity that is responsible for the CSS source. Previous studies of the H I closer to the core seem to preclude the assumption of a circum-nuclear disk of H I as the source of the accreting gas. We consider the cooling of gas from the hot X-ray halo as a possible alternative option for the fueling of the AGN, as suggested for other sources of similar radio power as B2 0258+35. This would provide a more likely explanation for the recurrent activity. Furthermore, if the previously made suggestion in the literature that the inner CSS may not be able to grow to large scales is correct, this implies that different cycles of activity may have different characteristics (e.g. radio power of the emission). Estimates are given for the age of the faint diffuse emission as well as for the current accretion rate, which agree well with literature values. If our assumptions about the accretion mechanism are correct, similar large-scale, relic-like structures should be more commonly found around early-type galaxies, which will hopefully be confirmed by the next generation of sensitive, low-frequency radio surveys.

show abstract

“…Nevertheless the majority of sources in our sample have double-lobe like morphologies and total flux densities that are quite stable over 20 years. Only 3 CSOs are firmly classified according to Fanti's suggestion that a CSO should have a core inbetween double lobes or have double lobes with twin jets/tails if a core is not detected (Fanti 2009). …”

Section: Discussionmentioning

confidence: 99%

The follow-up European VLBI Network observations of twelve GPS radio sources at 5 GHz

Cui

Liu²,

Liu

et al. 2010

A&A

View full text Add to dashboard Cite

Aims. Gigahertz peaked spectrum (GPS) radio sources are compact extragalactic radio sources, assumed to be young radio-loud active galactic nuclei and ideal objects for studying the early evolution of extragalactic radio sources. The Very Long Baseline Interferometry (VLBI) observation with high resolution is vital for studying the structure of these compact sources. Methods. 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 2008, respectively, to classify the source structure and to find compact symmetric objects (CSOs). Additionally, we carried out the 4.85 GHz flux density observations for these sources with the Urumqi 25-m telescope between the years 2007 and 2009 to study whether there is any variability in the total flux density of the GPS sources.Results. The results of the 5 GHz VLBI observations and total flux densities of these sources are presented in this paper. From the VLBI morphologies, the spectral indices of components and the total flux variability of the twelve targets, we firmly classify three sources J0210+0419, J1135−0021, and J2058+0540 as CSOs, and classify J1057+0012, J1203+0414, and J1600−0037 as corejet sources. The others J0323+0534, J0433−0229, J0913+1454, J1109+1043, and J1352+0232 are labelled CSO candidates, and J1352+1107 is a complex feature. Apart from core-jet sources, the total flux densities of the CSOs and candidates are quite stable at 5 GHz both during a long-term of ∼20 years relative to the PKS90 data and in a period between 2007 and 2009. The total flux densities are resolved-out by more than 20% in the 5 GHz VLBI images for 6 sources, probably because of diffuse emission. In addition, we estimated the jet viewing angles (Θ) for the confirmed CSOs by using the double-lobe flux ratio of the sources, the result being indicative of relatively large Θ for the CSOs.

show abstract

Radio properties of CSSs and GPSs

Abstract: Radio properties of CSSs/GPSs from continuum (polarization included) and spectral line information are concisely summarized.

Cited by 59 publications

References 62 publications

Radio spectra of bright compact sources at z>4.5

Radio spectra of bright compact sources at z>4.5

Recurrent radio emission and gas supply: the radio galaxy B2 0258+35

The follow-up European VLBI Network observations of twelve GPS radio sources at 5 GHz

Contact Info

Product

Resources

About