Reality or Mirage? Observational Test and Implications for the Claimed Extremely Magnified Quasar at z = 6.3

Pacucci, Fabio; Loeb, Abraham

doi:10.3847/1538-4357/ab6130

Cited by 15 publications

(13 citation statements)

References 49 publications

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“…We find that, for J0100+2802 to be magnified at this level, it would have to be an extremely yet uncharacteristically intrinsically-faint X-ray source. In addition, the implication posed by Pacucci & Loeb (2020) • If the population of z > 6 quasars is lensed following the predictions of Pacucci & Loeb (2020), which are needed to produce a magnification of µ = 450, then these quasars would be in tension with the Lusso & Risaliti (2016) L 2500 − α OX relation for lower-redshift quasars at a 3σ level, despite extensive evidence that the central engines of high-redshift quasars are not significantly different from those of low-redshift quasars.…”

Section: Discussionmentioning

confidence: 99%

“…Even if we accept enough uncertainty to allow for J0100+2802 to be an order of magnitude fainter than predicted, there is still one further test. If J0100+2802 were magnified by µ∼450, Pacucci & Loeb (2020) argue that we would expect a significant fraction of all known z > 6 quasars to be lensed as well. Pacucci & Loeb (2020) find that the detection of a source with such an extreme magnification requires β, the bright-end slope of the luminosity function -such that Φ(L) ∝ L −β -must be β ≥ 3.7.…”

Section: Constraints From the Broader Populationmentioning

confidence: 99%

“…If J0100+2802 were magnified by µ∼450, Pacucci & Loeb (2020) argue that we would expect a significant fraction of all known z > 6 quasars to be lensed as well. Pacucci & Loeb (2020) find that the detection of a source with such an extreme magnification requires β, the bright-end slope of the luminosity function -such that Φ(L) ∝ L −β -must be β ≥ 3.7. From this value we can derive P (µ), the probability of an individual quasar being lensed to a certain magnification (Pacucci & Loeb 2019).…”

Section: Constraints From the Broader Populationmentioning

confidence: 99%

“…For the β = 3.7 case, we simulate what the values of ∆α OX would be if each quasar was unmagnified for a randomly-drawn value of P (µ). Magnification probabilities are derived from Pacucci & Loeb (2020), who report…”

Section: Constraints From the Broader Populationmentioning

confidence: 99%

“…If J0100+2802 is lensed, a magnification of µ∼450 would be significant; as the black hole mass estimate is based partially on the quasar's luminosity, this would imply M BH < 10 9 M . And not only does µ∼450 for J0100+2802 remove one of the strongest pieces of evidence for significant mass growth in late-stage reionization, but it could also imply broader trends; Pacucci & Loeb (2020) argue that, for a µ∼450 quasar to exist, the expected distribution of magnification values would require that more of the z > 6 quasar population is lensed by µ 10.…”

Section: Introductionmentioning

confidence: 99%

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X-Ray Evidence Against the Hypothesis that the Hyper-Luminous z=6.3 Quasar J0100+2802 is Lensed

Connor,

Stern,

Bañados

et al. 2021

Preprint

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The z = 6.327 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802) is believed to be powered by a black hole more massive than 10 10 M , making it the most massive black hole known in the first billion years of the Universe. However, recent high-resolution ALMA imaging shows four structures at the location of this quasar, potentially implying that it is lensed with a magnification of µ ∼ 450 and thus its black hole is significantly less massive. Furthermore, for the underlying distribution of magnifications of z 6 quasars to produce such an extreme value, theoretical models predict that a larger number of quasars in this epoch should be lensed, implying further overestimates of early black hole masses. To provide an independent constraint on the possibility that J0100+2802 is lensed, we re-analyzed archival XMM-Newton observations of the quasar and compared the expected ratios of X-ray luminosity to rest-frame UV and IR luminosities. For both cases, J0100+2802's X-ray flux is consistent with the no-lensing scenario; while this could be explained by J0100+2802 being Xray faint, we find it does not have the X-ray or optical spectral features expected for an X-ray faint quasar. Finally, we compare the overall distribution of X-ray fluxes for known, typical z 6 quasars. We find a 3σ tension between the observed and predicted X-ray-to-UV flux ratios when adopting the magnification probability distribution required to produce a µ = 450 quasar.

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Section: Discussionmentioning

confidence: 99%

Section: Constraints From the Broader Populationmentioning

confidence: 99%

Section: Constraints From the Broader Populationmentioning

confidence: 99%

Section: Constraints From the Broader Populationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

X-Ray Evidence Against the Hypothesis that the Hyper-Luminous z=6.3 Quasar J0100+2802 is Lensed

Connor,

Stern,

Bañados

et al. 2021

Preprint

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Jetted radio-quiet quasars at z > 5

Sbarrato

Ghisellini

Giovannini

et al. 2021

A&A

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We report on the JVLA observations of three high-redshift active galactic nuclei (AGNs) that have black hole masses estimated to be among the largest known. Two of them, SDSS J0100+2802 and SDSS J0306+1853 at redshift 6.326 and 5.363, respectively, are radio-quiet AGNs according to the classic definition, while the third (B2 1023+25 at z = 5.284) is a powerful blazar. The JVLA data clearly show a radio structure in the first source and a radio emission with a relatively steep radio spectrum in the second one, indicating the presence of a radio jet and a diffuse component. Therefore, being radio-quiet does not exclude the presence of a powerful relativistic jet, which has important consequences on population studies and on the ratio between jetted and non-jetted AGNs. We can estimate the viewing angle of these jets, and this allows us to find, albeit with some uncertainty, the density of black holes with a mass in excess of 1010 M⊙ at high redshifts. We found that their density in jetted AGNs is very large in the redshift bin 5–6 and comparable with the overall AGN population of the same optical luminosity. Jets might thus play a crucial role in the fast formation and evolution of the most massive black holes in the early Universe. They are more common than what is expected from wide radio surveys with milliJansky flux sensitivity. Deeper JVLA or very-long-baseline interferometry observations are key to discovering a possible relativistic jet population hiding in plain sight at very high redshift. The discovery of powerful relativistic jets associated with the most massive black holes in the early Universe revives the question: is the jet instrumental for a rapid growth of the black hole or, instead, is the black hole mass the main driver for the jet formation?

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Lensing in the darkness: a Bayesian analysis of 22 Chandra sources at z ≳ 6 shows no evidence of lensing

Pacucci

Foord

Gordon

et al. 2022

Monthly Notices of the Royal Astronomical Society

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More than 200 quasars have been detected so far at z > 6, with only one showing clear signs of strong gravitational lensing. Some studies call for a missing population of lensed high-z quasars, but their existence is still in doubt. A large fraction of high-z quasars being lensed would have a significant effect on the shape of the intrinsic quasar luminosity function (QLF). Here, we perform the first systematic search for lensed X-ray-detected quasars at z ≳ 6 employing a Bayesian analysis, with the code baymax, to look for morphological evidence of multiple images that may escape a visual inspection. We analyzed a sample of 22 quasars at z > 5.8 imaged by the Chandra X-ray observatory and found none with statistically significant multiple images. In the sub-sample of the 8 sources with photon counts >20 we exclude multiple images with separations r > 1″ and count ratios f > 0.4, or with separations as small as 0${^{\prime\prime}_{.}}$7 and f > 0.7 at 95% confidence level. Comparing this non-detection with predictions from theoretical models suggesting a high and a low lensed fraction, we placed upper limits on the bright-end slope, β, of the QLF. Using only the sub-sample with 8 sources, we obtain, in the high-lensing model, a limit β < 3.38. Assuming no multiple source is present in the full sample of 22 sources, we obtain β < 2.89 and β < 3.53 in the high and low lensing models, respectively. These constraints strongly disfavor steep QLF shapes previously proposed in literature.

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Reality or Mirage? Observational Test and Implications for the Claimed Extremely Magnified Quasar at z = 6.3

Cited by 15 publications

References 49 publications

X-Ray Evidence Against the Hypothesis that the Hyper-Luminous z=6.3 Quasar J0100+2802 is Lensed

X-Ray Evidence Against the Hypothesis that the Hyper-Luminous z=6.3 Quasar J0100+2802 is Lensed

Jetted radio-quiet quasars at z > 5

Lensing in the darkness: a Bayesian analysis of 22 Chandra sources at z ≳ 6 shows no evidence of lensing

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