A search for distant radio galaxies from SUMSS and NVSS - III. Radio spectral energy distributions and the z-  correlation

Klamer, I. J.; Ekers, R. D.; Bryant, Julia J.; Hunstead, R. W.; Sadler, E. M.; Breuck, C. De

doi:10.1111/j.1365-2966.2006.10714.x

Cited by 90 publications

(152 citation statements)

References 65 publications

(91 reference statements)

Supporting

Mentioning

136

Contrasting

Order By: Relevance

“…The idea of the interaction between radio plasma and dense ISM affecting the radio emission has indeed been proposed for high-z radio galaxies to explain e.g. the correlation between the steepness of the spectral index and the redshift of the sources (Athreya & Kapahi 1998;Klamer et al 2006). The possibility of a higher incidence of powerful radio sources associated with disk galaxies at high-z has been brought up by Norris et al (2008), although they have so far identified only one possible candidate in their deep field.…”

Section: Radio Sources Like Pks 1814-637: How Rare?mentioning

confidence: 99%

PKS 1814-637: a powerful radio-loud AGN in a disk galaxy

Morganti

Holt

Tadhunter

et al. 2011

A&A

View full text Add to dashboard Cite

We present a detailed study of PKS 1814-637, a rare case of powerful radio source (P 5 GHz = 4.1 × 10 25 W Hz −1 ) hosted by a disk galaxy. Optical images have been used to model the host galaxy morphology confirming it to be dominated by a strong (and warped) disk component that is observed close to edge-on to the line of sight. This is the first radio galaxy found to reside in a disk dominated galaxy with radio luminosity equivalent to powerful FRII objects. At radio wavelengths, PKS 1814-637 is about 480 pc in diameter and it is classified as a compact steep spectrum (CSS) source; such sources are usually considered to be radio sources observed in the early stages of their evolution. However, the optical and mid-IR spectroscopic properties of PKS1814-637 show more in common with Seyfert galaxies than they do with radio galaxies, with the detection of H 2 , and PAH emission features, along with HI and silicate absorption features, providing evidence for a rich ISM which is likely to be related to the disk morphology of the host galaxy. We argue that the interaction between the radio plasma and the rich ISM in this and similar objects may have boosted their radio emission, allowing them to more easily enter flux limited samples of radio sources. In this case, PKS 1814-637 represents a type of "imposter": an intrinsically low power object that is selected in a radio flux limited sample because of the unusually efficient conversion of jet power into radio emission. This would make PKS 1814-637 an extreme example of the effects of jet-cloud interactions in galaxies containing a rich ISM, and perhaps a missing link between radio galaxies and radio-loud Seyfert galaxies. However, it is unlikely that jet-cloud interactions alone can account for the unusually powerful radio emission compared to Seyfert galaxies, and it is probable that the jet in PKS 1814-637 is also intrinsically more powerful than in typical Seyfert galaxies, perhaps due to a higher bulge and black hole mass. The estimated BH mass is indeed higher than the majority of Seyfert galaxies in the local Universe. We speculate that sources similar to PKS1814-637 are likely to be more common at high redshifts, because of the enhanced probability at earlier epochs of triggering radio sources in moderately massive bulges that are also gas-rich.

show abstract

Section: Radio Sources Like Pks 1814-637: How Rare?mentioning

confidence: 99%

PKS 1814-637: a powerful radio-loud AGN in a disk galaxy

Morganti

Holt

Tadhunter

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…Miley & De Breuck 2008;Klamer et al 2006;Verkhodanov & Khabibullina 2010;Singh et al 2014), and several recent studies have failed to find a correlation between the spectral index and redshift (Ker et al 2012;Singh et al 2014;Smolčić et al 2014). The exact definition of a USS source (based on spectral index) differs between authors, e.g., α 608 MHz 327 MHz < −1.1 (Wieringa & Katgert 1992), α 4.85 GHz 151 MHz < −0.981 (Blundell et al 1998 (Singh et al 2014).…”

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

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

“…Extended gas disks within the radio galaxy Best (2000) pointed out that radio galaxies with very extended radio sources are particularly good candidates for being cluster central galaxies because the pressure from the Mpc-scale intracluster medium boosts the luminosity of the radio source even for comparably extended jets (see also Athreya et al 1998;Klamer et al 2006). Many authors have previously suggested that the progenitors of brightest cluster galaxies are likely to be found among HzRGs (e.g., Pentericci et al 2001;Miley et al 2006;Hatch et al 2009), andWylezalek et al (2013) find from IRAC imaging that TXS 2353-003 is even associated with the most strongly pronounced overdensity within their sample.…”

Section: Partial Agn Illumination Of Ambient Halo Cloudsmentioning

confidence: 99%

Defying jet-gas alignment in two radio galaxies atz~ 2 with extended light profiles: Similarities to brightest cluster galaxies

Collet

Nesvadba

Breuck

et al. 2015

A&A

Self Cite

View full text Add to dashboard Cite

We report the detection of extended warm ionized gas in two powerful high-redshift radio galaxies, NVSS J210626-314003 at z = 2.10 and TXS 2353-003 at z = 1.49, that does not appear to be associated with the radio jets. This is contrary to what would be expected from the alignment effect, a characteristic feature of distant, powerful radio galaxies at z ≥ 0.6. The gas also has smaller velocity gradients and line widths than most other high-z radio galaxies with similar data. Both galaxies are part of a systematic study of 50 high-redshift radio galaxies with SINFONI, and are the only two that are characterized by the presence of high surface-brightness gas not associated with the jet axis and by the absence of such gas aligned with the jet. Both galaxies are spatially resolved with ISAAC broadband imaging covering the rest-frame R band, and have extended wings that cannot be attributed to line contamination. We argue that the gas and stellar properties of these galaxies are more akin to gas-rich brightest cluster galaxies in cool-core clusters than the general population of high-redshift radio galaxies at z > ∼ 2. In support of this interpretation, one of our sources, TXS 2353-003, for which we have Hα narrowband imaging, is associated with an overdensity of candidate Hα emitters by a factor of ∼8 relative to the field at z = 1.5. We discuss possible scenarios of the evolutionary state of these galaxies and the nature of their emission line gas within the context of cyclical AGN feedback.

show abstract

A search for distant radio galaxies from SUMSS and NVSS - III. Radio spectral energy distributions and the z- correlation

Cited by 90 publications

References 65 publications

PKS 1814-637: a powerful radio-loud AGN in a disk galaxy

PKS 1814-637: a powerful radio-loud AGN in a disk galaxy

Radio spectra of bright compact sources at z>4.5

Defying jet-gas alignment in two radio galaxies atz~ 2 with extended light profiles: Similarities to brightest cluster galaxies

Contact Info

Product

Resources

About