Parsec-scale properties of the radio brightest jetted AGN at<i>z</i>&gt; 6

Spingola, Cristiana; Dallacasa, D.; Belladitta, S.; Caccianiga, A.; Giroletti, M.; Moretti, A.; Orienti, M.

doi:10.1051/0004-6361/202039458

Cited by 56 publications

(57 citation statements)

References 63 publications

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“…From the candidate jet emission reported here, the jets could have extended to ∼50 kpc, and the implied duration of jet launching is, assuming v ∼ 0.3c, of order 1 Myr. Recent interferometric observations of the z = 6.1 blazar PSO J0309 + 27 by Spingola et al (2020) showed jets with projected sizes of hundreds of parsecs; while these structures are potentially larger given the viewing angle, they, in addition to the observations of Momjian et al (2018), are in contrast to the limited effect of jets predicted by Regan et al (2019) and further support the notion that these jets could be aiding in accretion.…”

Section: Discussionmentioning

confidence: 60%

“…PJ352−15 is the source of the most distant extended (kiloparsec-scale) radio jets yet seen (Momjian et al 2018; but see also Spingola et al 2020), and it is therefore an ideal candidate to investigate the potential for IC interactions between relativistic particles in jets and the cosmic microwave background (CMB). IC/CMB has long been associated with the X-ray emission seen with jets, dating back to the first observations with Chandra (Chartas et al 2000;Schwartz et al 2000), although a number of issues have been raised against possible detections of this effect at low redshifts (Meyer et al 2015;Breiding et al 2017).…”

Section: Evidence For Inverse Compton/cosmic Microwave Backgroundmentioning

confidence: 99%

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Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Connor

Bañados

Stern

et al. 2021

ApJ

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We present deep (265 ks) Chandra X-ray observations of PSO J352.4034−15.3373, a quasar at z = 5.831 that, with a radio-to-optical flux ratio of R > 1000, is one of the radio-loudest quasars in the early universe and is the only quasar with observed extended radio jets of kiloparsec scale at z ≳ 6. Modeling the X-ray spectrum of the quasar with a power law, we find a best fit of Γ = 1.99 − 0.28 + 0.29 , leading to an X-ray luminosity of L 2 – 10 = 1.26 − 0.33 + 0.45 × 10 45 erg s − 1 and an X-ray to UV brightness ratio of α OX = −1.45 ± −0.11. We identify a diffuse structure 50 kpc (∼8″) to the NW of the quasar along the jet axis that corresponds to a 3σ enhancement in the angular density of emission and can be ruled out as a background fluctuation with a probability of P = 0.9985. While with few detected photons the spectral fit of the structure is uncertain, we find that it has a luminosity of L 2–10 ∼ 1044 erg s−1. These observations therefore potentially represent the most distant quasar jet yet seen in X-rays. We find no evidence for excess X-ray emission where the previously reported radio jets are seen (which have an overall linear extent of 0.″28), and a bright X-ray point source located along the jet axis to the SE is revealed by optical and NIR imaging to not be associated with the quasar.

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Section: Discussionmentioning

confidence: 60%

Section: Evidence For Inverse Compton/cosmic Microwave Backgroundmentioning

confidence: 99%

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Connor

Bañados

Stern

et al. 2021

ApJ

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“…High-redshift radio-loud quasars at z > 5 are critical for probing the physical conditions at the end of the reionization epoch and for studying the early evolutionary stage of the radioloud AGN and the coevolution with their host galaxies (e.g., Bañados et al 2021;Khorunzhev et al 2021;Ighina et al 2021). Of these objects, four are identified as blazars, which mostly have a core-jet morphology (e.g., Romani et al 2004;Frey et al 2010Frey et al , 2015Spingola et al 2020). About half of the objects have been observed at milliarcsecond (mas) resolution by the European Very Long Baseline Interferometry (VLBI) Network (EVN) or the Very Long Baseline Array (VLBA; e.g., Frey et al 2003Frey et al , 2005Frey et al , 2008Frey et al , 2011Momjian et al 2003Momjian et al , 2008Momjian et al , 2018Momjian et al , 2021Romani et al 2004;Cao et al 2014;Gabányi et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The radio spectral turnover of radio-loud quasars at $z>5$

Shao,

Wagg,

Wang

et al. 2021

Preprint

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We present Karl G. Jansky Very Large Array (VLA) S-(2-4 GHz), C-(4-8 GHz), and X-band (8-12 GHz) continuum observations toward seven radio-loud quasars at z > 5. This sample has previously been found to exhibit spectral peaks at observed-frame frequencies above ∼1 GHz. We also present upgraded Giant Metrewave Radio Telescope (uGMRT) band-2 (200 MHz), band-3 (400 MHz), and band-4 (650 MHz) radio continuum observations toward eight radio-loud quasars at z > 5, selected from our previous GMRT survey, in order to sample their low-frequency synchrotron emission. Combined with archival radio continuum observations, all ten targets show evidence for spectral turnover. The turnover frequencies are ∼1-50 GHz in the rest frame, making these targets gigahertzpeaked-spectrum (GPS) or high-frequency-peaker (HFP) candidates. For the nine well-constrained targets with observations on both sides of the spectral turnover, we fit the entire radio spectrum with absorption models associated with synchrotron self-absorption and free-free absorption (FFA). Our results show that FFA in an external inhomogeneous medium can accurately describe the observed spectra for all nine targets, which may indicate an FFA origin for the radio spectral turnover in our sample. As for the complex spectrum of J114657.79+403708.6 at z = 5.00 with two spectral peaks, it may be caused by multiple components (i.e., core-jet) and FFA by the high-density medium in the nuclear region. However, we cannot rule out the spectral turnover origin of variability. Based on our radio spectral modeling, we calculate the radio loudness R 2500 Å for our sample, which ranges from 12 +1 −1 to 674 +61 −51 .

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“…At high redshift, we include the other three sources from D20, the sample from (Saxena et al 2019) and the radio-loud QSO from Bañados et al (2018). The two radio-loud QSOs at z > 6 come from Ighina et al (2021) and Spingola et al (2020). MG 1131+0456 is a radio-loud lensed galaxy (Stern & Walton 2020).…”

Section: An Extreme Radio-to-near-ir Ratiomentioning

confidence: 99%

The nature and likely redshift of GLEAM J0917–0012

Drouart

Seymour

Broderick

et al. 2021

Publ. Astron. Soc. Aust.

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We previously reported a putative detection of a radio galaxy at $z=10.15$ , selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The redshift of this source, GLEAM J0917–0012, was based on three weakly detected molecular emission lines observed with the Atacama Large Millimetre Array (ALMA). In order to confirm this result, we conducted deep spectroscopic follow-up observations with ALMA and the Karl Jansky Very Large Array (VLA). The ALMA observations targeted the same CO lines previously reported in Band 3 (84–115 GHz) and the VLA targeted the CO(4-3) and [CI(1-0)] lines for an independent confirmation in Q-band (41 and 44 GHz). Neither observation detected any emission lines, removing support for our original interpretation. Adding publicly available optical data from the Hyper Suprime-Cam survey, Widefield Infrared Survey Explorer (WISE), and Herschel Space Observatory in the infrared, as well as $<$ 10 GHz polarisation and 162 MHz inter-planetary scintillation observations, we model the physical and observational characteristics of GLEAM J0917–0012 as a function of redshift. Comparing these predictions and observational relations to the data, we are able to constrain its nature and distance. We argue that if GLEAM J0917–0012 is at $z<3,$ then it has an extremely unusual nature, and that the more likely solution is that the source lies above $z=7$ .

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Parsec-scale properties of the radio brightest jetted AGN atz> 6

Cited by 56 publications

References 63 publications

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

The radio spectral turnover of radio-loud quasars at $z>5$

The nature and likely redshift of GLEAM J0917–0012

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