Pith. sign in

REVIEW 2 major objections 4 minor 113 references

This paper claims that among 85 hyper-luminous quasars at z≈2–4, intrinsic 2–10 keV X-ray luminosity spans roughly two orders of magnitude at nearly fixed bolometric, UV, and mid-infrared luminosity, leaving about one-third of the sources i

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Complete X-ray coverage of 85 hyper-luminous quasars at z≈2-4 shows one-third are X-ray weak and X-ray luminosity is highly dispersed relative to UV and infrared luminosities.

T0 review reviewed 2026-08-04 challenge →

load-bearing objection Complete-sample X-ray census of hyper-luminous z~2-4 QSOs; the dispersion result is likely real, but the ~31% weak fraction leans on assumed NH for a third of the sample. the 2 major comments →

arxiv 2509.08055 v1 pith:JUXKO2HL submitted 2025-09-09 astro-ph.GA astro-ph.HE

The WISSH quasar project. XII. X-ray view of the most luminous quasi-stellar objects at Cosmic Noon

C. Degli Agosti , C. Vignali , E. Piconcelli , L. Zappacosta , E. Bertola , R. Middei , I. Saccheo , G. Vietri
show 20 more authors
F. Vito A. Bongiorno M. Bischetti G. Bruni S. Carniani G. Cresci C. Feruglio F. Salvestrini A. Travascio M. Gaspari E. Glikman E. Kammoun G. Lanzuisi M. Laurenti G. Miniutti C. Pinto V. Testa F. Tombesi A. Tortosa F. Fiore
This is my paper
classification astro-ph.GA astro-ph.HE
keywords X-ray properties of quasarshyper-luminous QSOsCosmic NoonX-ray weaknessbolometric correctionactive galactic nucleiCIV outflowsaccretion disk corona
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper analyzes the X-ray emission of all 85 quasars in the WISSH sample—the most luminous broad-line AGN known at Cosmic Noon (z≈2–4)—and shows that their 2–10 keV X-ray luminosity scatters by roughly two orders of magnitude even though their bolometric, ultraviolet, and mid-infrared luminosities are packed into narrow ranges. Roughly one-third of the sources are classified as X-ray weak, with broad absorption line quasars more often weak than non-BAL quasars. The authors interpret the scatter as intrinsic differences in the X-ray corona and inner accretion flow of hyper-luminous quasars, not as unmodelled absorption, because the photon-index distribution is normal and does not correlate with X-ray weakness. They also find a very tight correlation between the X-ray-to-optical offset and the X-ray-to-mid-infrared offset, which offers a way to recover intrinsic X-ray luminosity and even column density from UV and MIR measurements. If the claims hold, bolometric or single-band estimates of X-ray luminosity for individual luminous quasars are unreliable, and X-ray-selected views of the most luminous AGN population are incomplete.

Core claim

The central claim is that hyper-luminous QSOs at Cosmic Noon display a broad intrinsic spread in X-ray luminosity and X-ray-to-UV ratio at fixed accretion-disk output. For 85 WISSH quasars with Lbol>10^47 erg/s and z≈2–4, the paper measures L2−10 from spectral fits, hardness ratios, or assumed spectral shapes, and finds a large dispersion in L2−10 while Lbol, L2500, and λL6μm vary little. About 31% fall below Δ(α_OX)≤−0.2, the X-ray-weak threshold, with a higher fraction among BAL QSOs. The distribution of the photon index Γ is typical of lower-luminosity AGN, does not depend on Eddington ratio, and does not correlate strongly with X-ray weakness, arguing that missing absorption is not the p

What carries the argument

The analysis hinges on three named quantities: the X-ray-to-optical index α_OX = 0.3838 log(L_2keV/L_2500Å), its offset Δ(α_OX) from the L10 relation, and the offset Δ_{6μm,X} of L2−10 from the Stern (2015) X-ray–MIR relation. The load-bearing relation is Δ(α_OX) = (0.38±0.01) Δ_{6μm,X} − (0.01±0.01), whose tight scatter (rP=0.97) allows X-ray luminosity and intrinsic NH to be estimated from UV and MIR photometry alone. Supporting machinery includes photon-index spectral fitting for sources with ≥20 counts, the BEHR hardness-ratio method for 5–20 count sources, and the Weisskopf binomial detection method for ≤5 count sources, with intrinsic luminosities assumed at Γ=1.8 and NH=5×10^22 cm^-2.

Load-bearing premise

For the 30 faintest sources (≤5 X-ray counts), the paper assigns a fixed X-ray spectral shape (photon index 1.8) and a fixed absorbing column (5×10^22 hydrogen atoms per square centimetre); if the true spectral shapes of these faint quasars differ, the reported dispersion and the ≈31% X-ray-weak fraction would change.

What would settle it

Take the 30 faintest WISSH quasars and observe each with deep X-ray exposures until spectral fitting gives individual photon indices and column densities. If the NH distribution is not centered near 5×10^22 cm^-2, or if the true photon indices deviate systematically from 1.8, then the reported faint-end L2−10 values, the X-ray-weak fraction, and part of the broad kbol scatter would need revision.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

If this is right

  • If the dispersion is real, Lbol, L2500, and λL6μm cannot be used as reliable X-ray proxies for individual luminous QSOs; X-ray surveys are needed to classify them.
  • About one-third of the most luminous z≈2–4 quasars are X-ray weak (≈47% of BAL, ≈20% of non-BAL), so X-ray-selected samples miss a substantial fraction of the hyper-luminous population.
  • The tight Δ(α_OX)–Δ_{6μm,X} relation gives a practical way to estimate intrinsic 2–10 keV luminosity and, combined with observed X-ray flux, intrinsic column density from UV+WISE data.
  • X-ray weakness is linked to faster CIV outflows, supporting models in which a weak X-ray continuum avoids over-ionising the gas and allows wind launching.
  • No X-ray-weak to X-ray-normal transitions were seen in multi-epoch data, suggesting the X-ray-weak state persists over rest-frame timescales from days to years.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the faint-end luminosities are confirmed with deeper spectra, the X-ray-weak fraction may extend even beyond one-third, because the current assumption (NH=5×10^22 cm^-2) is tested statistically rather than source by source.
  • The tight Δ(α_OX)–Δ_{6μm,X} relation, if it holds in other quasar samples, would make it possible to build large X-ray luminosity catalogues from optical and MIR surveys and to flag candidate changing-look or absorbed sources for follow-up.
  • The blue non-BAL quasars in the forbidden region suggest the blow-out phase can occur without heavy dust reddening; a testable prediction is that their hosts should show feedback signatures similar to red quasars.
  • A direct test of the corona interpretation is simultaneous broad-band X-ray spectroscopy of X-ray-weak WISSH quasars: warm-corona and funnel models predict very steep Γ>3 spectra, which the paper does not observe in the sources with measured slopes.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 4 minor

Summary. This paper presents the X-ray analysis of the complete WISSH sample of 85 hyper-luminous broad-line QSOs at z~2-4, combining new proprietary Chandra observations with archival Chandra/XMM-Newton/Swift data. The analysis is tiered by photon statistics: spectral fitting for 39 sources with >=20 net counts, hardness-ratio modeling for 16 sources with 5-20 net counts, and assumed-spectrum luminosity estimates for 30 sources with <=5 net counts, 8 of which are undetected. The authors report a large dispersion in L2-10 and in the bolometric correction kbol despite the narrow distribution of Lbol, L2500 and lambda L6micron, classify about 31% of the sample as X-ray weak via Delta(alpha_OX)<=-0.2, find that the Gamma distribution is consistent with lower-luminosity AGN and does not correlate with Eddington ratio, identify blue QSOs in the forbidden region of the NH-lambda_Edd plane, confirm a correlation between L2-10 and CIV blueshift, and claim a very tight Delta(alpha_OX)-Delta_6micron_X relation. The qualitative conclusion is that the corona/accretion-flow properties vary widely among hyper-luminous QSOs and that single-band proxies for X-ray luminosity are unreliable for individual sources.

Significance. The paper is a valuable observational contribution: it provides homogeneous X-ray coverage and reanalysis of an entire sample at the highest AGN luminosities at Cosmic Noon, and the high-count sub-sample alone (39 sources, Table B.1) already shows a large L2-10 range relative to the narrow Lbol/UV/MIR ranges selected by WISSH. The null result on Gamma-lambda_Edd, the CIV-outflow correlation, and the identification of blue QSOs in the forbidden region are useful constraints for accretion models. The inclusion of complete data tables and the clear tiered analysis are strengths. However, the headline quantitative claim -- about one-third of WISSH QSOs are X-ray weak -- is dominated by the 30 low-count sources whose L2-10 is assigned under fixed spectral assumptions, and the reported Delta(alpha_OX)-Delta_6micron_X relation is largely tautological. The qualitative picture is plausible, but the quantitative claims need systematic-uncertainty work before the paper can be accepted.

major comments (2)
  1. [Section 3.2, Table B.3, Fig. 8] The X-ray-weak fraction of ~31% (Section 4.2) is not robust to the assumptions used for the 30 sources with <=5 net counts. Using Table E.1, 19 of the 26 sources with Delta(alpha_OX)<=-0.2 belong to this low-count group, including 8 undetected sources that are placed in the X-ray-weakest bin by construction. For these sources L2-10 is computed from Eq. (2) with fixed Gamma=1.8 and NH=5e22 cm^-2, the median of only 14 absorbed HC sources. The stated ~7% sensitivity is only the mean change when this one NH value is switched on/off; it does not propagate a realistic distribution of NH (e.g., 0 to 1e23 cm^-2). At z~2-4 the rest-frame 2-10 keV band falls in the photoelectrically absorbed observed band, so per-source errors can be several tenths of dex. Since many low-count sources have Delta(alpha_OX) near -0.2 (Table E.1), modest NH changes can move them across the X-ray-weak threshold. In a
  2. [Section 4.5, Eq. (6)] The claimed tight relation Delta(alpha_OX)=(0.38+-0.01)Delta_6micron_X - (0.01+-0.01) with r=0.97 and p=3e-50 is largely tautological. Delta(alpha_OX) is by definition a linear function of log L2keV plus a slowly varying function of L2500 A, while Delta_6micron_X is log L2-10 minus a function of lambda L6micron. Because L2500 A and lambda L6micron are tightly correlated and span a narrow range in WISSH, both variables are essentially linear functions of the same measured log L2-10. The authors themselves note this in the same section ('both Equation 3 and 5 can be expressed as a function of L2-10'), yet they still present Eq. (6) as a physically informative 'robust relation' and use it to claim a robust derivation of L2-10. This section should be reframed as a mathematical transformation/consistency check, with the tautology made explicit; the p-value and Pearson r should not be quoted a
minor comments (4)
  1. [Section 3.2] The sentence 'their values with and without NH change, on average, by ~7%' is ambiguous. It should specify the range and dispersion of the change, not just the mean, since the central concern is per-source systematic error in the L2-10 distribution.
  2. [Fig. 8 / Table E.1] The treatment of undetected sources should be clarified: the caption says all 8 are included in the X-ray-weakest bin, but two of them (WISSH15, WISSH26) have Delta(alpha_OX) upper limits that do not satisfy the <=-0.2 criterion. Please state explicitly whether these objects are counted as weak and how upper limits enter the histogram.
  3. [Section 4.3 / Fig. 9] The discussion of Gamma versus Delta(alpha_OX) is based only on the >=20-count sources. Most X-ray-weak sources do not have measured Gamma; the authors acknowledge this in Section 5.1, but the point should be stated more prominently in Section 4.3 to avoid the impression that the X-ray-weak population as a whole has a normal spectral slope.
  4. [Section 4.5] The text introducing Delta_6micron_X and Eq. (5) could be clearer about the redshift/band correction and the assumed photon index used to convert L2keV to L2-10; this is relevant to the tautology point.

Circularity Check

1 steps flagged

The Δ(αOX)–Δ6μm,X correlation (Eq. 6) is an algebraic consequence of both quantities sharing L2−10; the central X-ray-dispersion claim is not itself circular.

specific steps
  1. self definitional [Section 4.5, Eq. (6) and following paragraph]
    "We notice that once L2500 Å and λL6μm are known, both Equation 3 and 5 can be expressed as a function of L2−10 (assuming a photon index, e.g. Γ≈1.8−2, to estimate L2−10 from L2keV). Therefore, L2−10 can be derived through Equation 6."

    Δ(αOX) (Eq. 3) is αOX−αOX,L10, with αOX=0.3838 log(L2keV/L2500); for fixed Γ, log L2keV = log L2−10 + const. Δ6μm,X (Eq. 5) is log L2−10 − log L2−10,S15(λL6μm). Thus both variables are the same measured log L2−10 plus a reference term that depends only on L2500 or L6μm, which span a narrow range in WISSH. Regressing Δ(αOX) on Δ6μm,X therefore regresses 0.3838 log L2−10 + slowly varying offset against log L2−10 + slowly varying offset, forcing a slope ≈0.38 (exactly the αOX coefficient) and a near-unity correlation. The r=0.97, p=3×10−50 is a consequence of shared input, not an independent physical law; the paper's own sentence confirms both can be expressed as functions of L2−10.

full rationale

The paper's main observational result—a broad L2−10 distribution and ~31% X-ray-weak fraction despite narrow Lbol/L2500/λL6μm—is based on X-ray measurements and is not circular: L2−10 comes from Chandra/XMM counts, while Lbol, L2500, and λL6μm come from independent SED/WISE data. The assumed NH=5×10^22 cm^-2 for the 30 low-count sources is a systematic approximation, not a fitted parameter used to predict the same data, so it affects accuracy but does not make the claim definitional. The genuinely circular piece is Eq. (6): the tight Δ(αOX)–Δ6μm,X correlation is an algebraic artifact of both offsets being linear in the same L2−10. This is a partial circularity in one presented result, but it does not undermine the central accretion-physics dispersion claim. No load-bearing self-citation chain or imported uniqueness theorem is present.

Axiom & Free-Parameter Ledger

3 free parameters · 4 axioms · 0 invented entities

The quantitative claims rest on a small number of assumed X-ray spectral shapes and external scaling relations; the most consequential are the fixed Γ=1.8 and NH=5e22 for low-count sources, which directly affect the reported X-ray-weak fraction.

free parameters (3)
  • Fixed photon index for faint sources = Γ=1.8
    Used for 16 hardness-ratio sources and 30 low-count sources to convert count rates/fluxes to L2-10; systematic uncertainty not propagated.
  • Assumed intrinsic column density for <=5 count sources = NH=5×10^22 cm^-2
    Median NH of 14 absorbed HC-WISSH sources; applied to all 30 faint sources. The paper estimates a ~7% average effect on L2-10.
  • X-ray weakness threshold = Δ(αOX) ≤ -0.2
    Adopted from Luo et al. (2015); the reported 31% fraction depends on this choice, and undetected sources are placed in the weakest bin.
axioms (4)
  • standard math Cosmology H0=70, Ωm=0.27, ΩΛ=0.73
    Used for distances and luminosities throughout.
  • domain assumption X-ray spectra of Type 1 AGN are adequately described by an absorbed power law with Γ≈1.8 in the 0.3-10 keV band
    Assumed for hardness-ratio and faint-source luminosity estimates; ignores soft excess and reflection, which may bias NH and L2-10 for low-count sources.
  • domain assumption Single-epoch Hβ virial relation (Eq. 4) gives reliable MBH with 0.3 dex systematic
    Used to compute Eddington ratios; authors note BLR size may be smaller in luminous QSOs.
  • domain assumption External scaling relations (D20 for kbol, L10 for αOX, S15 for L2-10-MIR) are valid benchmarks for the WISSH population
    Offsets and X-ray-weak classifications are defined relative to these literature relations.

reviewed 2026-08-04 · how reviews work

0 comments
Cite this review

Pith. "Pith review of The WISSH quasar project. XII. X-ray view of the most luminous quasi-stellar objects at Cosmic Noon." pith.science (2026). https://pith.science/paper/JUXKO2HL

@misc{pith2026250908055,
  author       = {Pith},
  title        = {Pith review of: The WISSH quasar project. XII. X-ray view of the most luminous quasi-stellar objects at Cosmic Noon},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/JUXKO2HL}},
  note         = {Machine review of arXiv:2509.08055}
}
Share X Bluesky LinkedIn Reddit HN
abstract

To improve our knowledge of nuclear emission in luminous QSOs at Cosmic Noon, we studied the X-ray emission of the WISE/SDSS-selected hyper-luminous (WISSH) QSO sample: 85 broad-line AGN with $L_{bol}>few\times 10^{47}\,erg\,s^{-1}$ at $z\sim 2-4$. Our aim is to characterise their X-ray spectra and explore relations between X-ray luminosity and other bands, comparing powerful QSOs with the general AGN population. We performed spectral analysis for about half of the sample; 16 sources were analysed via their hardness ratio; for the others we estimated their intrinsic luminosity $L_{2-10\,keV}$. Only 8 sources are undetected. We report a large dispersion in $L_{2-10\,keV}$ despite the narrow distribution of $L_{bol}$, $L_{2500\,\r{A}}$ and $\lambda L_{6\,\mu m}$ (about one-third of the sources classified as X-ray weak). This suggests differences in X-ray corona and accretion flow physics between hyper-luminous and less powerful AGN. X-ray photon index distribution is consistent with that of lower-$z$, lower-$L_{bol}$ AGN, and does not depend on the Eddington ratio ($\lambda_{Edd}$) or X-ray weakness. Most WISSH QSOs with intrinsic absorption estimates show little to no obscuration ($N_H \le 5\times 10^{22}\,cm^{-2}$). Among the obscured sources we find blue QSOs without broad absorption lines within the "forbidden region" of the $Log(N_H)-Log(\lambda_{Edd})$ plane, typically occupied by dust-reddened QSOs and associated with intense feedback. We confirm a correlation between $L_{2-10\,keV}$ and CIV line blueshift, a tracer of nuclear ionized outflows. Multi-wavelength data and complete X-ray coverage enabled the investigation of the disk-corona interplay at the highest luminosity regimes. The broad distribution of bolometric correction and X-ray - to - optical index suggest caution when using $L_{bol}$, $L_{2500\,\r{A}}$ or $L_{6\,\mu m}$ as direct X-ray proxy for individual luminous QSOs.

Figures

Figures reproduced from arXiv: 2509.08055 by A. Bongiorno, A. Tortosa, A. Travascio, C. Degli Agosti, C. Feruglio, C. Pinto, C. Vignali, E. Bertola, E. Glikman, E. Kammoun, E. Piconcelli, F. Fiore, F. Salvestrini, F. Tombesi, F. Vito, G. Bruni, G. Cresci, G. Lanzuisi, G. Miniutti, G. Vietri, I. Saccheo, L. Zappacosta, M. Bischetti, M. Gaspari, M. Laurenti, R. Middei, S. Carniani, V. Testa.

Figure 1
Figure 1. Figure 1: X-ray coverage of the WISSH sample. of radius ≈ 15 − 55 arcsec was used for the background, in￾stead. Spectra were extracted through the XMM-Newton SAS meta-task especget, which runs also the arfgen, rmfgen and backscale tasks. Thus, ARF and RMF matrices are calculated, and the source and background extraction region are re-scaled to obtain the spectra. 2.4. Swift-XRT observation The Swift-XRT observations… view at source ↗
Figure 2
Figure 2. Figure 2: (a) Chandra spectrum (re-binned for display purposes) of WISSH47 (z = 2.6987). We detect about 130 counts for this source and measure significant intrinsic absorption. The residuals are defined as (data - model) in units of σ. (b) NH − Γ contour plot for the best fit model of WISSH47. The blue, green, and red curves represent the 68%, 90%, and 99% confidence levels, respectively. fixed Γ = 1.8 (Piconcelli … view at source ↗
Figure 3
Figure 3. Figure 3: Intrinsic column density distribution for the HC-WISSH sam [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Log(L2−10) as a function of Lbol for the entire WISSH sample. The huge spread of WISSH QSOs in the kbol − Log(Lbol) plane was already apparent (although with half of the current sources) in Martocchia et al. (2017). This spread looks more evident due to the relatively narrow range of Lbol sampled by WISSH objects. Figure 6a shows the ratio of the observed kbol to the expected values at the same Lbol measur… view at source ↗
Figure 5
Figure 5. Figure 5: Bolometric correction as a function of Log(L [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: (a) Ratio of measured kbol values to expected kbol values from D20 as a function of Log(Lbol). WISSH QSOs are compared to literature samples; the symbols are the same as in [PITH_FULL_IMAGE:figures/full_fig_p007_6.png] view at source ↗
Figure 8
Figure 8. Figure 8 [PITH_FULL_IMAGE:figures/full_fig_p007_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: X-ray photon index as a function of ∆(αOX) for the sources with ≥ 20 counts. (a) Γobs derived using a power law model modified by Galactic absorption. (b) Cold absorption component included in the spectral model used to derive Γ (see Section 3.1.1). The BAL and non-BAL QSOs are represented as indigo and purple dots, respectively. The grey-shaded areas highlight the locus of X-ray-weak sources [PITH_FULL_I… view at source ↗
Figure 10
Figure 10. Figure 10: X-ray photon index as a function of Log( [PITH_FULL_IMAGE:figures/full_fig_p008_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Intrinsic column density (derived assuming [PITH_FULL_IMAGE:figures/full_fig_p009_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: (a) Intrinsic 2 − 10 keV luminosity as a function of λL6 µm. WISSH BAL and non-BAL objects are shown as indigo and purple stars, respectively, while the grey dots represent various comparison samples from Lanzuisi et al. (2009), Mateos et al. (2015), and S15. The black solid, dashed, and dotted lines correspond to the relation by S15, Lanzuisi et al. (2009), and Chen et al. (2017), respectively; (b) ∆(αOX… view at source ↗
Figure 13
Figure 13. Figure 13: Intrinsic 2 − 10 keV luminosity (top panel) and ∆(αOX) (bot￾tom panel) as a function of Civ velocity vCIV. WISSH non-BAL objects are shown as purple dots. The dispersion around the best fits (solid red lines) is given by plotting ≈ 200 realisations considering the values of slope and intercept within 1σ of the sampled marginalised posterior dis￾tribution (see Figures D.1b and D.1c, and Table D.1 for furth… view at source ↗
Figure 14
Figure 14. Figure 14: (a) Intrinsic 2 − 10 keV luminosity, (b) kbol/kbol,D20, and (c) photon index distributions. The histograms show the comparison between WISSH sources with ≥ 20 counts (green) and a sample of QSOs at z > 6 from Tortosa et al. (2024) (orange). – We estimated the presence of intrinsic absorption for the sources belonging to the HC-WISSH sample (≈ 65% of the entire WISSH sample). The vast majority of them exhi… view at source ↗

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

113 extracted references · 62 canonical work pages · 1 internal anchor

  1. [1]

    A., Czerny, B., Lasota, J

    Abramowicz, M. A., Czerny, B., Lasota, J. P., & Szuszkiewicz, E. 1988, ApJ, 332, 646

    1988

  2. [2]

    Arnaud, K. A. 1996, in Astronomical Data Analysis Software and Systems (ADASS) V , ed. G. H. Jacoby & J. Barnes (A.S.P. Conference Series)

    1996

  3. [3]

    D., et al

    Ballo, L., Severgnini, P., Ceca, R. D., et al. 2014, MNRAS, 444, 2580

    2014

  4. [4]

    H., Tueller, J., Markwardt, C

    Baumgartner, W. H., Tueller, J., Markwardt, C. B., et al. 2013, ApJS, 207, 19

    2013

  5. [5]

    L., Larson, D., Weiland, J

    Bennett, C. L., Larson, D., Weiland, J. L., et al. 2013, ApJS, 208, 54

    2013

  6. [6]

    2007, A&A, 467, 1432

    Bianchi, S., Guainazzi, M., Matt, G., & Fonseca Bonilla, N. 2007, A&A, 467, 1432

    2007

  7. [7]

    2021, A&A, 645, A33

    Bischetti, M., Feruglio, C., Piconcelli, E., et al. 2021, A&A, 645, A33

    2021

  8. [8]

    2018, A&A, 617, A82

    Bischetti, M., Piconcelli, E., Feruglio, C., et al. 2018, A&A, 617, A82

    2018

  9. [9]

    2017, A&A, 598, A122

    Bischetti, M., Piconcelli, E., Vietri, G., et al. 2017, A&A, 598, A122

    2017

  10. [10]

    2014, MNRAS, 443, 2077

    Bongiorno, A., Maiolino, R., Brusa, M., et al. 2014, MNRAS, 443, 2077

    2014

  11. [11]

    D., Mainieri, V ., et al

    Brightman, M., Silverman, J. D., Mainieri, V ., et al. 2013, MNRAS, 433, 2485

    2013

  12. [12]

    2019, A&A, 630, A111

    Bruni, G., Piconcelli, E., Misawa, T., et al. 2019, A&A, 630, A111

    2019

  13. [13]

    2024, ApJ, 973, 149

    Byrne, L., Faucher-Giguère, C.-A., Wellons, S., et al. 2024, ApJ, 973, 149

    2024

  14. [14]

    & Gu, W.-M

    Cao, X. & Gu, W.-M. 2022, ApJ, 936, 141

    2022

  15. [15]

    J., Hickox, R

    Chen, C.-T. J., Hickox, R. C., Goulding, A. D., et al. 2017, ApJ, 837, 145

    2017

  16. [16]

    F., Liu, J., et al

    Cheng, H., Liu, B. F., Liu, J., et al. 2020, MNRAS, 495, 1158

    2020

  17. [17]

    S., Ostriker, J

    Choi, E., Somerville, R. S., Ostriker, J. P., Naab, T., & Hirschmann, M. 2018, ApJ, 866, 91

    2018

  18. [18]

    2014, MNRAS, 439, 2736

    Delvecchio, I., Gruppioni, C., Pozzi, F., et al. 2014, MNRAS, 439, 2736

    2014

  19. [19]

    2015, ApJ, 806, 22

    Du, P., Hu, C., Lu, K.-X., et al. 2015, ApJ, 806, 22

    2015

  20. [20]

    2016, ApJ, 825, 126

    Du, P., Lu, K.-X., Zhang, Z.-X., et al. 2016, ApJ, 825, 126

    2016

  21. [21]

    2018, ApJ, 856, 6

    Du, P., Zhang, Z.-X., Wang, K., et al. 2018, ApJ, 856, 6

    2018

  22. [22]

    2017, A&A, 636, A73

    Duras, F., Bongiorno, A., Piconcelli, E., et al. 2017, A&A, 636, A73

    2017

  23. [23]

    2020, A&A, 636, A73, (D20 in this paper)

    Duras, F., Bongiorno, A., Ricci, F., et al. 2020, A&A, 636, A73, (D20 in this paper)

    2020

  24. [24]

    C., Lohfink, A., Kara, E., et al

    Fabian, A. C., Lohfink, A., Kara, E., et al. 2015, MNRAS, 451, 4375

    2015

  25. [25]

    C., Vasudevan, R

    Fabian, A. C., Vasudevan, R. V ., & Gandhi, P. 2008, MNRASL, 385, L43 Faucher-Giguère, C.-A. & Quataert, E. 2012, MNRAS, 425, 605

    2008

  26. [26]

    2017, A&A, 601, A143

    Fiore, F., Feruglio, C., Shankar, F., et al. 2017, A&A, 601, A143

    2017

  27. [27]

    2009, ApJ, 693, 447

    Fiore, F., Puccetti, S., Brusa, M., et al. 2009, ApJ, 693, 447

    2009

  28. [28]

    J., et al

    Gabriel, C., Denby, M., Fyfe, D. J., et al. 2004, in Astronomical Data Analysis Software and Systems (ADASS) XIII, ed. F. Ochsenbein, M. G. Allen, & D. Egret (A.S.P. Conference Series)

    2004

  29. [29]

    2009, A&A, 502, 457

    Gandhi, P., Horst, H., Smette, A., et al. 2009, A&A, 502, 457

    2009

  30. [30]

    2014, ApJL, 783, L10

    Gaspari, M., Brighenti, F., Temi, P., & Ettori, S. 2014, ApJL, 783, L10

    2014

  31. [31]

    & S˛ adowski, A

    Gaspari, M. & S˛ adowski, A. 2017, ApJ, 837, 149

    2017

  32. [32]

    2020, Nature Astronomy, 4, 10

    Gaspari, M., Tombesi, F., & Cappi, M. 2020, Nature Astronomy, 4, 10

    2020

  33. [33]

    & Proga, D

    Giustini, M. & Proga, D. 2019, A&A, 630, A94

    2019

  34. [34]

    2024, MN- RAS, 528, 711 GRA VITY Collaboration, Amorim, A., Bourdarot, G., et al

    Glikman, E., LaMassa, S., Piconcelli, E., Zappacosta, L., & Lacy, M. 2024, MN- RAS, 528, 711 GRA VITY Collaboration, Amorim, A., Bourdarot, G., et al. 2024, A&A, 684, A167

    work page 2024

  35. [35]

    & Maraschi, L

    Haardt, F. & Maraschi, L. 1991, ApJL, 380, L51

    work page 1991

  36. [36]

    & Maraschi, L

    Haardt, F. & Maraschi, L. 1993, ApJ, 413, 507

    1993

  37. [37]

    F., Richards, G

    Hopkins, P. F., Richards, G. T., & Hernquist, L. 2007, ApJ, 654, 731

    2007

  38. [38]

    2024, submitted to PASJ [arXiv:2412.03653]

    Inayoshi, K., Kimura, S., & Noda, H. 2024, submitted to PASJ [arXiv:2412.03653]

    Pith/arXiv arXiv 2024

  39. [39]

    C., Ricci, C., & Celotti, A

    Ishibashi, W., Fabian, A. C., Ricci, C., & Celotti, A. 2018, MNRAS, 479, 3335

    work page 2018

  40. [40]

    W., Brandt, W

    Just, D. W., Brandt, W. N., Shemmer, O., et al. 2007, ApJ, 665, 1004

    work page 2007

  41. [41]

    Kelly, B. C. 2007, ApJ, 665, 1489

    2007

  42. [42]

    S., et al

    Krongold, Y ., Nicastro, F., Brickhouse, N. S., et al. 2003, ApJ, 597, 832

    2003

  43. [43]

    E., Richards, G

    Kruczek, N. E., Richards, G. T., Gallagher, S. C., et al. 2011, ApJ, 142, 130

    work page 2011

  44. [44]

    & Done, C

    Kubota, A. & Done, C. 2018, MNRAS, 480, 1247

    2018

  45. [45]

    B., Banerji, M., Fabian, A

    Lansbury, G. B., Banerji, M., Fabian, A. C., & Temple, M. J. 2020, MNRAS, 495, 2652

    work page 2020

  46. [46]

    2009, A&A, 498, 67

    Lanzuisi, G., Piconcelli, E., Fiore, F., et al. 2009, A&A, 498, 67

    work page 2009

  47. [47]

    J., & McDowell, J

    Laor, A., Fiore, F., Elvis, M., Wilkes, B. J., & McDowell, J. C. 1994, ApJ, 435, 611

    work page 1994

  48. [48]

    2022, A&A, 657, A57

    Laurenti, M., Piconcelli, E., Zappacosta, L., et al. 2022, A&A, 657, A57

    2022

  49. [49]

    2024, A&A, 689, A337

    Laurenti, M., Tombesi, F., Vagnetti, F., et al. 2024, A&A, 689, A337

    2024

  50. [50]

    Leighly, K. M. 2004, ApJ, 611, 125

    work page 2004

  51. [51]

    Spectroastrometry and Reverberation Mapping of Active Galactic Nuclei. II. Measuring Geometric Distances and Black Hole Masses of Four Nearby Quasars

    Li, Y .-R., Shangguan, J., Wang, J.-M., et al. 2025, submitted to ApJ [arXiv:2502.18856]

    work page internal anchor Pith review Pith/arXiv arXiv 2025

  52. [52]

    N., et al

    Liu, H., Luo, B., Brandt, W. N., et al. 2021, ApJ, 910, 103

    2021

  53. [53]

    N., Alexander, D

    Luo, B., Brandt, W. N., Alexander, D. M., et al. 2014, ApJ, 794, 70

    work page 2014

  54. [54]

    N., Hall, P

    Luo, B., Brandt, W. N., Hall, P. B., et al. 2015, ApJ, 805, 122

    2015

  55. [55]

    2010, A&A, 512, A34, (L10 in this paper)

    Lusso, E., Comastri, A., Vignali, C., et al. 2010, A&A, 512, A34, (L10 in this paper)

    work page 2010

  56. [56]

    Lutz, D., Maiolino, R., Spoon, H. W. W., & Moorwood, A. F. M. 2004, A&A, 418, 465

    work page 2004

  57. [57]

    & Haardt, F

    Madau, P. & Haardt, F. 2024, ApJL, 976, L24

    work page 2024

  58. [58]

    2001, A&A, 365, 28

    Maiolino, R., Marconi, A., Salvati, M., et al. 2001, A&A, 365, 28

    work page 2001

  59. [59]

    2017, A&A, 608, A51

    Martocchia, S., Piconcelli, E., Zappacosta, L., et al. 2017, A&A, 608, A51

    work page 2017

  60. [60]

    J., Alonso-Herrero, A., et al

    Mateos, S., Carrera, F. J., Alonso-Herrero, A., et al. 2015, MNRAS, 449, 1422

    2015

  61. [61]

    C., & Piro, L

    Matt, G., Perola, G. C., & Piro, L. 1991, A&A, 247, 25

    work page 1991

  62. [62]

    A., Brusa, M., Lanzuisi, G., et al

    Matzeu, G. A., Brusa, M., Lanzuisi, G., et al. 2023, A&A, 670, A182

    work page 2023

  63. [63]

    McKernan, B., Yaqoob, T., & Reynolds, C. S. 2007, MNRAS, 379, 1359

    work page 2007

  64. [64]

    & Heinz, S

    Merloni, A. & Heinz, S. 2008, MNRAS, 388, 1011

    2008

  65. [65]

    2024, A&A, 682, A34 Article number, page 14 of 25 C

    Merloni, A., Lamer, G., Liu, T., et al. 2024, A&A, 682, A34 Article number, page 14 of 25 C. Degli Agosti et al.: The WISSH quasar project

    work page 2024

  66. [66]

    A., Bosman, S

    Meyer, R. A., Bosman, S. E. I., & Ellis, R. S. 2019, MNRAS, 487, 3305

    work page 2019

  67. [67]

    N., Schneider, D

    Miniutti, G., Brandt, W. N., Schneider, D. P., et al. 2012, MNRAS, 425, 1718

    work page 2012

  68. [68]

    & Fabian, A

    Miniutti, G. & Fabian, A. C. 2004, MNRAS, 349, 1435

    work page 2004

  69. [69]

    2024, MNRAS, 532, 666

    Mizukoshi, S., Minezaki, T., Sameshima, H., et al. 2024, MNRAS, 532, 666

    work page 2024

  70. [70]

    2023, A&A, 679, A84

    Musiimenta, B., Brusa, M., Liu, T., et al. 2023, A&A, 679, A84

    work page 2023

  71. [71]

    2019, A&A, 632, A109

    Nardini, E., Lusso, E., Risaliti, G., et al. 2019, A&A, 632, A109

    work page 2019

  72. [72]

    N., Luo, B., et al

    Ni, Q., Brandt, W. N., Luo, B., et al. 2018, MNRAS, 480, 5184

    work page 2018

  73. [73]

    & Narayan, R

    Pacucci, F. & Narayan, R. 2024, ApJ, 976, 96

    2024

  74. [74]

    L., Siemiginowska, A., et al

    Park, T., Kashyap, V . L., Siemiginowska, A., et al. 2006, ApJ, 652, 610

    work page 2006

  75. [75]

    R., Reeves, J

    Patrick, A. R., Reeves, J. N., Porquet, D., et al. 2012, MNRAS, 426, 2522

    work page 2012

  76. [76]

    L., et al

    Perrotta, S., Hamann, F., Zakamska, N. L., et al. 2019, MNRAS, 488, 4126

    work page 2019

  77. [77]

    2005, A&A, 432, 15

    Piconcelli, E., Jimenez-Bailón, E., Guainazzi, M., et al. 2005, A&A, 432, 15

    work page 2005

  78. [78]

    A., Done, C., & Osborne, J

    Pounds, K. A., Done, C., & Osborne, J. P. 1995, MNRAS, 277, L5

    work page 1995

  79. [79]

    2007, in The Central Engine of Active Galactic Nuclei, ed

    Proga, D. 2007, in The Central Engine of Active Galactic Nuclei, ed. L. C. Ho & J.-M. Wang (A.S.P. Conference Series)

    work page 2007

  80. [80]

    L., Hewett, P

    Rankine, A. L., Hewett, P. C., Banerji, M., & Richards, G. T. 2020, MNRAS, 492, 4553

    work page 2020

Showing first 80 references.

This paper was first reviewed by deepseek-v4-flash on August 4, 2026.