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Discovery of three z>6.5 quasars in the VISTA Kilo-degree Infrared Galaxy (VIKING) survey

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Paper breakdownThe authors' claims, conditions and measurements, as JSON Signed receiptProof this review has not been altered
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B. P. Venemans (1), J. R. Findlay (2), W. J. Sutherland (3), G. De Rosa (4), R. G. McMahon (5, 6), R. Simcoe (7), E. A. Gonzalez-Solares (5)
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K. Kuijken (8), J. R. Lewis (5) ((1) MPIA Heidelberg, (2) Durham University, (3) Queen Mary, London, (4) Ohio State University, (5) IoA Cambridge, (6) KICC Cambridge, (7) MIT, (8) Leiden Observatory)

Cosmology and Nongalactic Astrophysics · Submitted 14 Nov 2013

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim Here we report the discovery of three new z>6.4 quasars in 332 square degrees of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4.

how it is stated · asserted 1.00 read the record →

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arXiv ID1311.3666 (version 2)
Pith IDYDR4P26S, Pith's permanent record of this paper and its review
Citation(2) Durham University, (3) Queen Mary, (4) Ohio State University, (5) IoA Cambridge, 6), (6) KICC Cambridge, (7) MIT, (8) Leiden Observatory), B. P. Venemans (1), E. A. Gonzalez-Solares (5), G. De Rosa (4), J. R. Findlay (2), J. R. Lewis (5) ((1) MPIA Heidelberg, K. Kuijken (8), London, R. G. McMahon (5, R. Simcoe (7), W. J. Sutherland (3). "Discovery of three z>6.5 quasars in the VISTA Kilo-degree Infrared Galaxy (VIKING) survey." arXiv:1311.3666 (2013). https://pith.science/paper/YDR4P26S
Claim paper

The compiled record

The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Open the compiled record

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 8,531 input tokens, $0.0004 reported.

What the abstract itself states, as probabilities: claims first 0.20 · states limitation 0.47 · human participants 0.02 · controlled comparison 0.15 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.97 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, and it also probes the intergalactic medium in the early universe. Optical surveys have to date discovered more than 60 quasars up to z~6.4, a limit set by the use of the z-band and CCD detectors. Only one z>6.4 quasar has been discovered, namely the z=7.08 quasar ULAS J1120+0641, using near-infrared imaging. Here we report the discovery of three new z>6.4 quasars in 332 square degrees of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4. The newly discovered quasars have redshifts of z=6.60, 6.75, and 6.89. The absolute magnitudes are between -26.0 and -25.5, 0.6-1.1 mag fainter than ULAS J1120+0641. Near-infrared spectroscopy revealed the MgII emission line in all three objects. The quasars are powered by black holes with masses of ~(1-2)x10^9 M_sun. In our probed redshift range of 6.44<z<7.44 we can set a lower limit on the space density of supermassive black holes of \rho(M_BH>10^9 M_sun) > 1.1x10^(-9) Mpc^(-3). The discovery of three quasars in our survey area is consistent with the z=6 quasar luminosity function when extrapolated to z~7. We do not find evidence for a steeper decline in the space density of quasars with increasing redshift from z=6 to z=7.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, and it also probes the intergalactic medium in the early universe. background 1.00 0.05 0.02 asserted 0.94
s1 Optical surveys have to date discovered more than 60 quasars up to z~6.4, a limit set by the use of the z-band and CCD detectors. background 0.92 0.04 0.02 asserted 1.00
s2 Only one z>6.4 quasar has been discovered, namely the z=7.08 quasar ULAS J1120+0641, using near-infrared imaging. background 0.69 0.06 0.03 asserted 1.00
s3 Here we report the discovery of three new z>6.4 quasars in 332 square degrees of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4. contribution 0.87 0.98 0.87 asserted 1.00
s4 The newly discovered quasars have redshifts of z=6.60, 6.75, and 6.89. result 1.00 0.96 0.22 asserted 1.00
s5 The absolute magnitudes are between -26.0 and -25.5, 0.6-1.1 mag fainter than ULAS J1120+0641. result 1.00 0.90 0.05 asserted 1.00
s6 Near-infrared spectroscopy revealed the MgII emission line in all three objects. result 0.80 0.94 0.04 asserted 1.00
s7 The quasars are powered by black holes with masses of ~(1-2)x10^9 M_sun. result 0.96 0.86 0.07 asserted 0.99
s8 In our probed redshift range of 6.44<z<7.44 we can set a lower limit on the space density of supermassive black holes of \rho(M_BH>10^9 M_sun) > 1.1x10^(-9) Mpc^(-3). result 0.99 0.97 0.17 asserted 1.00
s9 The discovery of three quasars in our survey area is consistent with the z=6 quasar luminosity function when extrapolated to z~7. interpretation 0.92 0.86 0.19 hedged possibility 0.98
s10 We do not find evidence for a steeper decline in the space density of quasars with increasing redshift from z=6 to z=7. result 0.62 0.96 0.27 asserted 0.99

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.96.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper
Original abstract

Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, and it also probes the intergalactic medium in the early universe. Optical surveys have to date discovered more than 60 quasars up to z~6.4, a limit set by the use of the z-band and CCD detectors. Only one z>6.4 quasar has been discovered, namely the z=7.08 quasar ULAS J1120+0641, using near-infrared imaging. Here we report the discovery of three new z>6.4 quasars in 332 square degrees of the Visible and Infrared Survey Telescope for Astronomy Kilo-degree Infrared Galaxy (VIKING) survey, thus extending the number from 1 to 4. The newly discovered quasars have redshifts of z=6.60, 6.75, and 6.89. The absolute magnitudes are between -26.0 and -25.5, 0.6-1.1 mag fainter than ULAS J1120+0641. Near-infrared spectroscopy revealed the MgII emission line in all three objects. The quasars are powered by black holes with masses of ~(1-2)x10^9 M_sun. In our probed redshift range of 6.44<z<7.44 we can set a lower limit on the space density of supermassive black holes of \rho(M_BH>10^9 M_sun) > 1.1x10^(-9) Mpc^(-3). The discovery of three quasars in our survey area is consistent with the z=6 quasar luminosity function when extrapolated to z~7. We do not find evidence for a steeper decline in the space density of quasars with increasing redshift from z=6 to z=7.

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References
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80 later papers cite it

Evidence: substantial. 62 of the citing papers share no author with it, and 11 of those carry a confident label from Pith's citation classifier.

Pith read 14 of the 105 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 2 papers · 1 by the same authors

By the same authors

How the literature uses it

9 arXiv papers cite this in 11 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 9 sentences without a confident label

Uses its data or values 1 paper
Cites it as background 1 paper

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