VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 AT<i>Z</i>= 6.12

Momjian, Emmanuel; Carilli, Christopher L.; McGreer, Ian D.

doi:10.1088/0004-6256/136/1/344

Cited by 43 publications

(55 citation statements)

References 29 publications

(41 reference statements)

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“…The quasar J1659+2101 is somewhat more resolved than the others. Notably, the two most distant (z ∼ 6) quasars (J0836+0054, Frey et al 2003Frey et al , 2005J1427+3312, Frey et al 2008bMomjian et al 2008) observed with VLBI to date share much similar properties.…”

Section: Discussionmentioning

confidence: 91%

“…Recent surveys that did not apply spectral selection criteria (e.g. Mosoni et al 2006;Frey et al 2008a), and VLBI observations of individual z ∼ 6 quasars (J0836+0054, Frey et al 2003Frey et al , 2005J1427+3312, Frey et al 2008bMomjian et al 2008) indicate that there is a less-known steep-spectrum population of compact radio AGNs at high redshifts. These sources have so far been able to escape discovery for a variety of reasons: (i) their radio flux density is relatively low for VLBI, requiring high data rate phase-referenced observations; (ii) due to their steep spectra, they are generally not considered useful for VLBI experiments; (iii) for most of them, spectroscopic redshifts are simply not yet available.…”

Section: Introductionmentioning

confidence: 99%

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High-resolution images of five radio quasars at early cosmological epochs

Frey¹,

Paragi²,

Gurvits³

et al. 2010

A&A

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Context. Until now, there have only been seven quasars at z > 4.5 whose the high-resolution radio structure had been studied in detail with Very Long Baseline Interferometry (VLBI) imaging. Aims. We almost double the number of VLBI-imaged quasars at these high redshifts with the aim of studying their redshift-dependent structural and physical properties in a larger sample. Methods. We observed five radio quasars (J0813+3508, J1146+4037, J1242+5422, J1611+0844, and J1659+2101) at 4.5 < z < 5 with the European VLBI Network (EVN) at 1.6 GHz on 29 October 2008 and at 5 GHz on 22 October 2008. The angular resolution achieved ranges from 1.5 to 25 milli-arcsec (mas), depending on the observing frequency, the position angle in the sky, and the source's celestial position. Results. The sources are all somewhat extended on mas scales, but compact enough to be detected at both frequencies. With one exception of a flat-spectrum source (J1611+0844), their compact emission is characterised by a steep radio spectrum. We found no evidence of Doppler-boosted radio emission in the quasars in our sample. The radio structure of one of them (J0813+3508) is extended to ∼7 , which corresponds to 43 kpc projected linear size. Many of the highest redshift compact radio sources are likely to be young, evolving objects, far-away cousins of the powerful gigahertz peaked-spectrum (GPS) and compact steep-spectrum (CSS) sources that populate the Universe at lower redshifts.

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Section: Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

High-resolution images of five radio quasars at early cosmological epochs

Frey¹,

Paragi²,

Gurvits³

et al. 2010

A&A

View full text Add to dashboard Cite

show abstract

“…Additionaly, recent VLBI studies suggest that the naive ⋆ E-mail: gabanyik@sgo.fomi.hu; krisztina.g@gmail.com expectation that relativistically beamed sources (blazars) should dominate the high-redshift radio-loud quasar population might not be true. There seems to exist a population of steep-spectrum high-redshift (z 4.5) radio-loud quasars (Momjian et al 2008;Frey et al 2008Frey et al , 2010, which may be very young radio quasars, similar to the gigahertzpeaked spectrum (GPS) sources observed in the local Universe (Frey et al 2010). On the other hand, a few highredshift, beamed blazars are known as well.…”

Section: Introductionmentioning

confidence: 97%

VLBI observation of the newly discovered z = 5.18 quasar SDSS J0131−0321

Gabányi

Cseh

Frey³

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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Few high-redshift, radio-loud quasars are known to date. The extremely luminous, radio-bright quasar, SDSS J013127.34−032100.1 was recently discovered at a redshift of z = 5.18. We observed the source with high resolution very long baseline interferometry (VLBI) at 1.7 GHz with the European VLBI Network (EVN) and found a single compact radio component. We estimated a lower limit to the brightness temperature of the detected radio component, T B ∼ 10 11 K. Additionaly, when compared to archival radio data, the source showed significant flux density variation. These two findings are indicative of the blazar nature of the source.

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“…(The powerlaw spectral index α is defined as S ∝ ν α , where S is the flux density and ν the frequency.) The 1.4-GHz and 1.6-GHz VLBI images of the first z > 6 radio quasar, J1427+3312 (Momjian et al 2008;Frey et al 2008, respectively) revealed a prominent double structure. The two resolved components are separated by ∼28 mas (∼160 pc); to calculate linear sizes and luminosities, we assume a flat cosmological model with H 0 = 70 km s −1 Mpc −1 , Ω m = 0.3, and Ω Λ = 0.7.…”

Section: Introductionmentioning

confidence: 98%

Into the central 10 pc of the most distant known radio quasar

Frey¹,

Paragi

Gurvits

et al. 2011

A&A

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Context. There are about 60 quasars known at redshifts z > 5.7 to date. Only three of them are detected in the radio above 1 mJy flux density at 1.4 GHz frequency. Among them, J1429+5447 (z = 6.21) is the highest-redshift radio quasar known at present. These rare, distant, and powerful objects provide important insight into the activity of the supermassive black holes in the Universe at early cosmological epochs and into the physical conditions of their environment. Aims. We studied the compact radio structure of J1429+5447 on the milli-arcsecond (mas) angular scale to compare the structural and spectral properties with those of another two z ∼ 6 radio-loud quasars, J0836+0054 (z = 5.77) and J1427+3312 (z = 6.12). Methods. We performed Very Long Baseline Interferometry (VLBI) imaging observations of J1429+5447 with the European VLBI Network (EVN) at 1.6 GHz on 2010 June 8, and at 5 GHz on 2010 May 27. Results. Based on its observed radio properties, the compact but somewhat resolved structure on linear scales of <100 pc, and the steep spectrum, the quasar J1429+5447 is remarkably similar to J0836+0054 and J1427+3312. To answer the question whether the compact steep-spectrum radio emission is a "universal" feature of the most distant radio quasars, it is essential to study more yet to be discovered radio-loud active galactic nuclei at z > 6.

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VERY LARGE ARRAY AND VERY LONG BASELINE ARRAY OBSERVATIONS OF THE HIGHEST REDSHIFT RADIO-LOUD QSO J1427+3312 ATZ= 6.12

Cited by 43 publications

References 29 publications

High-resolution images of five radio quasars at early cosmological epochs

High-resolution images of five radio quasars at early cosmological epochs

VLBI observation of the newly discovered z = 5.18 quasar SDSS J0131−0321

Into the central 10 pc of the most distant known radio quasar

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