RC J0311+0507: A candidate for superpowerful radio galaxies in the early universe at redshift z = 4.514

Копылов, А. И.; Goss, W. M.; Pariiskii, Yu. N.; Soboleva, N. S.; Верходанов, О. В.; Темирова, А. В.; Желенкова, О. П.

doi:10.1134/s1063773706070012

Cited by 34 publications

(28 citation statements)

References 36 publications

(23 reference statements)

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“…5 we also noticed that the majority of blazars found in the literature occupies the portion of the plot at very high R (64% have log(R)>2.5), suggesting that DES0141-54 has a high probability of being a blazar. However there are two objects with R greater than or equal to that of DES0141-54: J0311+0507 (Kopylov et al 2006) at z=4.51 and J2102+6015 (Sowards-Emmerd et al 2004) at z=4.57 respectively. For both of them no evidence of Doppler boosting from Very Long Baseline Interferometry (VLBI) observations is reported in the literature, therefore these sources are not classified as blazars.…”

Section: Radio Propertiesmentioning

confidence: 97%

An extremely X-ray weak blazar at z = 5

Belladitta

Moretti

Caccianiga

et al. 2019

A&A

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We present the discovery and properties of DESJ014132.4-542749.9 (DES0141-54), a new powerful radio-loud active galactic nucleus (AGN) in the early Universe (z=5.0). It was discovered by cross-matching the first data release of the Dark Energy Survey (DES DR1) with the Sidney University Molonglo Survey (SUMSS) radio catalog at 0.843 GHz. This object is the first radio-loud AGN at high redshift discovered in the DES. The radio properties of DES0141-54, namely its very large radio-loudness (R>10 4 ), the high radio luminosity (L 0.8GHz =1.73×10 28 W Hz −1 ), and the flatness of the radio spectrum (α=0.35) up to very high frequencies (120 GHz in the source's rest frame), classify this object as a blazar, meaning, a radio-loud AGN observed along the relativistic jet axis. However, the X-ray luminosity of DESJ0141-54 is much lower compared to those of the high redshift (z≥4.5) blazars discovered so far. Moreover its X-ray-to-radio luminosity ratio (log( L [0.5−10]keV L 1.4GHz )=9.96±0.30 Hz) is small also when compared to lower redshift blazars: only 2% of the low-z population has a similar ratio. By modeling the spectral energy distribution we found that this peculiar X-ray weakness and the powerful radio emission could be related to a particularly high value of the magnetic field. Finally, the mass of the central black hole is relatively small (M BH = 3-8 ×10 8 M ) compared to other confirmed blazars at similar redshift, making DES0141-54 the radio-loud AGN that host the smallest supermassive black hole ever discovered at z≥5. 1 The criteria adopted to classify a source as a blazar are not unique and they can be based on both radio and X-ray properties. Here the six sources considered as blazars at z≥5.0 are: J0906+6930 (z=5.47, Romani et al.

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Section: Radio Propertiesmentioning

confidence: 97%

An extremely X-ray weak blazar at z = 5

Belladitta

Moretti

Caccianiga

et al. 2019

A&A

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“…The USS method has proven successful: most of the high-redshift sources identified through radio observations were selected using this method (De Breuck et al 2000;Verkhodanov & Khabibullina 2010;Singh et al 2014), and it has also succeeded in finding sources out to z > 4 (e.g. Van Breugel et al 1999;Jarvis et al 2001;Kopylov et al 2006).…”

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.

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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.

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“…The fraction of distant radio galaxies is especially high among these very objects [39][40][41][42][43][44]. This criterion was used in studies that resulted in the discovery of the most distant radio galaxies with redshifts z > 4.5: z = 5.199 [45] and, z = 4.514 [46,47]. We simulated random positions of two hundred 10 × 10 areas outside the galactic plane (|b| > 20 • ), located more than 2 • from the closest clusters and radio galaxies and from each other (Fig.…”

Section: Methodsmentioning

confidence: 99%

Search for clustering of background objects near distant radio galaxies using the MST method

Keshelava

Верходанов

2015

Astrophys. Bull.

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The minimal spanning tree (MST) method was used to explore the statistical properties of field objects near distant radio galaxies (0.3 ≤ z ≤ 1.2) on SDSS images. The average diagrams of MST branch lengths were found to differ statistically for field objects near radio galaxies with z < 0.7 and z > 0.7, although zones of the subsample considered show no signs of clustering down to the SDSS limiting magnitude at a significance level greater than 5σ.

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RC J0311+0507: A candidate for superpowerful radio galaxies in the early universe at redshift z = 4.514

Cited by 34 publications

References 36 publications

An extremely X-ray weak blazar at z = 5

An extremely X-ray weak blazar at z = 5

Radio spectra of bright compact sources at z>4.5

Search for clustering of background objects near distant radio galaxies using the MST method

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