Spectroscopy of “Big Trio” objects using the “Scorpio” spectrograph of the 6-m telescope of the Special Astrophysical Observatory

Parijskij, Yurij N.; Копылов, А. И.; Темирова, А. В.; Soboleva, N. S.; Желенкова, О. П.; Верходанов, О. В.; Goss, W. M.; Фатхуллин, Т. А.

doi:10.1134/s1063772910080019

Cited by 14 publications

(10 citation statements)

References 14 publications

(18 reference statements)

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“…However, because the 4C survey has a resolution of 11.5 arcmin, the flux density of the nearby sources will blend with that of J0311+0507, we discarded the match. We, for the same reason, discarded the matches to Bursov (1996) (at 0.96,2.3,3.94 and 7.69 GHz), Parijskij et al (2010) (at 0.5, 1.4 and 3.94 GHz), Parijskij et al (1996) (at 1.425 GHz), Pariiskii et al (1992) (at 3.945 GHz) and Braude et al (1979) (at 16.7 MHz).…”

Section: J0311+0507mentioning

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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Section: J0311+0507mentioning

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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“…Useful information about the population of objects with high radio luminosities can be extracted from the Big Trio project. Photometric and spectral redshifts of objects with steep and ultrasteep spectra in the field of view of the KHOLOD experiment are presented in [38]. Redshifts could be determined for 54 of the 71 studied objects: of these ten have z > 2, three have z > 3, and one has z > 4 (RCJ 0311+0507, z = 4.514).…”

Section: The Nature Of the Weak Radio Sourcesmentioning

confidence: 99%

“…The radio luminosity is proportional to M 2.5 SMBH , where MSMBH is the mass of the supermassive black hole [53]. An object from the Big Trio project (RCJ0311+0507) has the most massive black hole, according to [38]. z > 1 have been found using this method, although it remains unclear why objects with ultra-steep spectra have high radio luminosities.…”

Section: Conclusion (The Big Trio Project and The 21st Century)mentioning

confidence: 99%

“…9, 10). The signal-to-noise ratio in this case is S/N > 100, the object's flux densities are S 7.6 cm = 135 mJy and S 21 cm = 537 mJy, its largest angular size in the radio is 2.8 , and its spectral index is α = 1.37 [18,25,26,36,38].…”

Section: Conclusion (The Big Trio Project and The 21st Century)mentioning

confidence: 99%

“…Figure 4 shows the drop in the number of radio sources with redshift for these 54 objects. Based on data published in 2007-2010 [38,[47][48][49][50][51], there are currently 194 known radio sources with z > 2, 47 with z > 3, and 9 with z > 4. It is possible to extrapolate these data to the entire sky, taking into account the KHOLOD survey region (0.005 ster; Fig.…”

Section: The Nature Of the Weak Radio Sourcesmentioning

confidence: 99%

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The KHOLOD experiment: A search for a new population of radio sources

et al. 2012

Self Cite

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Published data from long-term observations of a strip of sky at declination δ ≈ 5 • carried out at 7.6 cm on the RATAN-600 radio telescope are used to estimate some statistical properties of radio sources. Limits on the sensitivity of the survey due to noise imposed by background sources, which dominates the radiometer sensitivity, are refined. The vast majority of noise due to background sources is associated with known radio sources (for example, from the NVSS with a detection threshold of 2.3 mJy) with normal steep spectra (α = 0.7-0.8, S ∝ ν −α ), which have also been detected in new deep surveys at decimeter wavelengths. When all such objects are removed from the observational data, this leaves another noise component that is observed to be roughly identical in independent groups of observations. We suggest this represents a new population of radio sources that are not present in known catalogs at the 0.6 mJy level at 7.6 cm. The studied redshift dependence of the number of steep-spectrum objects shows that the sensitivity of our survey is sufficient to detect powerful FRII radio sources at any redshift, right to the epoch of formation of the first galaxies. The inferred new population is most likely associated with low-luminosity objects at redshifts z < 1. In spite of the appearance of new means of carrying out direct studies of distant galaxies, searches for objects with very high redshifts among steep and ultra-steep spectrum radio sources remains an effective method for studying the early Universe.

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Mapping the “invisible” circumgalactic medium around a z ∼ 4.5 radio galaxy with MUSE

Wang

Wylezalek

Breuck

et al. 2021

A&A

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In this paper we present Multi Unit Spectroscopic Explorer integral field unit spectroscopic observations of the ∼70 × 30 kpc2 Lyα halo around the radio galaxy 4C04.11 at z = 4.5077. High-redshift radio galaxies are hosted by some of the most massive galaxies known at any redshift and are unique markers of concomitant powerful active galactic nucleus (AGN) activity and star formation episodes. We map the emission and kinematics of the Lyα across the halo as well as the kinematics and column densities of eight H I absorbing systems at −3500 < Δv < 0 km s−1. We find that the strong absorber at Δv ∼ 0 km s−1 has a high areal coverage (30 × 30 kpc2), being detected across a large extent of the Lyα halo, a significant column density gradient along the southwest to northeast direction, and a velocity gradient along the radio jet axis. We propose that the absorbing structure, which is also seen in C IV and N V absorption, represents an outflowing metal-enriched shell driven by a previous AGN or star formation episode within the galaxy and is now caught up by the radio jet, leading to jet-gas interactions. These observations provide evidence that feedback from AGN in some of the most massive galaxies in the early Universe may play an important role in redistributing material and metals in their environments.

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Spectroscopy of “Big Trio” objects using the “Scorpio” spectrograph of the 6-m telescope of the Special Astrophysical Observatory

Cited by 14 publications

References 14 publications

Radio spectra of bright compact sources at z>4.5

Radio spectra of bright compact sources at z>4.5

The KHOLOD experiment: A search for a new population of radio sources

Mapping the “invisible” circumgalactic medium around a z ∼ 4.5 radio galaxy with MUSE

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