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Constraining Disk-to-Corona Power Transfer Fraction, Soft X-ray Excess Origin, and Black Hole Spin Population of Type-1 AGN across Mass Scales

T0 review · 3 major / 5 minor · reviewed 2026-08-10 · deepseek-v4-flash

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Pith's one-line read This paper derives the disk-to-corona power transfer fraction in 11 AGN, finds a strong correlation with black hole mass times accretion rate squared that validates the standard α-disk model with variable coupling, and constrains the soft…

desk verdict Careful spectral fitting undermined by a circular validation claim for the disk-to-corona power transfer fraction. read the letter →

arxiv 2501.15380 v2 pith:ELSGJPZL submitted 2025-01-26 astro-ph.HE astro-ph.GAphysics.space-ph

Labani Mallick (CITA National Fellow) , Ciro Pinto , John Tomsick , Alex Markowitz , Andrew Fabian , Samar Safi-Harb , James Steiner , Fabio Pacucci
show 1 more author
William Alston
This is my paper · ORCID
classification astro-ph.HEastro-ph.GAphysics.space-ph
keywords accretiondisksX-rayreflectionspectroscopysoftexcessblackholespinactivegalacticnucleicoronadisk-to-coronapowertransfer
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

Using joint XMM-Newton and NuSTAR spectra from 0.3 to 78 keV for 11 Type-1 active galactic nuclei, the paper tests whether the standard $\alpha$-disk model, with a fraction $f$ of the disk energy carried into a hot corona, explains the inner-disk densities that reflection spectroscopy actually measures. It finds that $f$ correlates strongly with $\log(M_{\rm BH}\dot{m}^2)$, as the model predicts, and reports the first systematic measurement of $f$ in any accreting object, with a sample median of 0.68. The same fits show that high-density relativistic reflection can explain the disputed soft X-ray excess along with the broad iron line and Compton hump in most sources, with a separate warm Comptonizing component still needed in three. If correct, the disk–corona coupling becomes a predictable function of black hole mass and accretion rate, the soft X-ray excess is a hybrid phenomenon, and the AGN spin census grows by roughly 20%.

What carries the argument

The carrying machinery is the SZ94 density relation for a radiation-pressure-dominated Shakura–Sunyaev disk with power-transfer fraction $f$, used in reverse: the reflection fit supplies the disk density, and Eq. (1) is solved for $f$ at $r=10r_s$, the radius at which model and measured densities agree for all sources. The spectral engine is the relxillCp high-density relativistic reflection model, which allows the disk density to vary up to $\log(n_e/{\rm cm^{-3}})=20$ and the coronal temperature to vary, with a broken-power-law emissivity profile. Model comparison uses MCMC posteriors and the Deviance Information Criterion to decide between canonical-density reflection, high-density reflection, and an added warm Comptonization component. The confirmation step is the Spearman rank correlation between the derived $f$ and $\log(M_{\rm BH}\dot{m}^2)$.

What would settle it

Take a source observed at several epochs with different luminosities but fixed $\dot{m}$ (or with independent $\dot{m}$ monitoring) and check whether the $f$ values derived from the reflection density remain constant; if $f$ tracks flux, the assumption that the fitted $n_e$ is the local SZ94 density at $r=10r_s$ is not valid.

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Extended reading notes

Core claim

The paper's central claim is that the standard radiation-pressure-dominated $\alpha$-disk model, augmented by a variable fraction $f$ of disk power transferred to the X-ray corona, is validated by the observed relation between the derived $f$ and $\log(M_{\rm BH}\dot{m}^2)$. For each source, the electron density $n_e$ measured by fitting the high-density relativistic reflection model relxillCp is inserted into the SZ94 density formula $n_e \propto \alpha^{-1}r^{3/2}\dot{m}^{-2}(1-f)^{-3}$ evaluated at $r=10r_s$ with $\alpha=0.1$, giving $f$ for that source; the resulting values show a strong positive correlation (Spearman $\rho_s=0.73$, $p=0.01$). The paper reports the first systematic calculation of this transfer fraction in any accreting object, with a sample median of $0.68$, and shows that the transferred power can soften the coronal spectrum. It also finds that high-density relativistic reflection alone describes the soft X-ray excess together with the broad iron line and Compton hump in 8 of the 11 sources, while 3 require an additional warm Comptonization component, implying a hybrid origin for the soft X-ray excess. The same reflection fits yield black hole spin measurements that add about 20% to the available AGN spin sample across $\log(M_{\rm BH}/M_\odot)\sim5.5{-}9$.

Load-bearing premise

The calculation treats the electron density returned by the reflection fit as the local density of a standard disk supported by radiation pressure, evaluated exactly at 10 Schwarzschild radii with the viscosity parameter fixed at 0.1; if the fitted density is an average over a density gradient, or the inner disk is not radiation-pressure dominated where the reflection arises, the derived $f$ values and the correlation that validates the model do not follow.

Editorial extensions

If this is right

  • The $f$–$\log(M_{\rm BH}\dot{m}^2)$ correlation validates the standard $\alpha$-disk model with a variable disk-to-corona power transfer fraction.
  • Because $f$ ranges from a few percent to above 98 percent across the sample, the canonical assumption of a fixed low disk density is insufficient; density must be fitted.
  • The soft X-ray excess has a hybrid origin: relativistic reflection from a dense, ionized disk in most sources, plus warm Comptonization in a minority.
  • Higher disk-to-corona power transfer is associated with softer primary X-ray spectra, consistent with the injected disk photons cooling the corona.
  • Eleven new spin measurements extend the AGN spin census across nearly the full supermassive black hole mass range, increasing the sample by about 20%.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Beyond the paper, if the correlation holds in a larger sample, $f$ could be predicted from optical/UV accretion-rate estimates, turning the disk-to-corona fraction into an input rather than an output of spectral models.
  • The same inversion of the SZ94 relation could be applied to stellar-mass black hole X-ray binaries, testing whether the disk-to-corona coupling law is universal across roughly six orders of magnitude in mass; the paper does not do this.
  • A decisive check of the assumed radius $r=10r_s$ would be to use reflection models that return density as a function of radius, or to compare the derived $f$ with independent coronal-height or emissivity measurements.
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Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

3 major / 5 minor

Summary. This paper presents joint XMM-Newton/NuSTAR (0.3–78 keV) spectral modeling of 11 Type-1 AGN spanning log(M_BH/M_sun) ≈ 5.9–9.1, using the relxillCp high-density relativistic reflection model with MCMC parameter exploration and DIC-based model comparison. The authors report three headline results: (i) a hybrid origin for the soft X-ray excess, with high-density disk reflection alone fitting 8/11 sources and an additional warm Comptonization component required for 3/11 (NGC 4748, Mrk 110, PG 1426+015); (ii) the first systematic derivation of the disk-to-corona power transfer fraction f, obtained by inverting the Svensson–Zdziarski (1994) density formula (Eq. 1) at fixed α = 0.1 and r = 10 r_s, with a reported sample median f ≈ 0.7 (0.68 in the separate abstract); and (iii) a claimed validation of the standard α-disk model via a strong correlation between f and log(M_BH mdot^2) (Spearman ρ_s = 0.73, p = 0.01). Additional results include median hot-corona temperature and optical depth (63 keV and 0.85) and spin measurements that increase the published AGN spin census by roughly 20%.

Significance. The spectral modeling is careful and transparent: MCMC chains with convergence checks, DIC tables for model selection, per-source appendices with spectra, residuals, and corner plots, and a fully documented fitting pipeline. If valid, the f measurement would open a new observational window on disk–corona coupling, and the correlation test would be a strong confirmation of the SZ94/SS73 framework. Unfortunately, the central validation claim is circular and unsound for the reasons given in Major Comment 1: f is derived from Eq. (1) using the same M_BH and mdot variables against which it is later correlated, so the reported ρ_s = 0.73 restates the measured lack of an n_e–M_BH mdot^2 anti-correlation rather than testing the model. The remaining contributions — the systematic soft-excess census and the spin measurements — are useful but largely confirmatory of earlier work (JJ19; Mallick et al. 2022; Porquet et al. 2024).

major comments (3)
  1. [§4.4, Eq. (1), Figs. 8–9] The claimed validation of the α-disk model is circular. Equation (1) is inverted to solve for f from the measured density, yielding f = 1 − [C′/(n_e,obs M_BH mdot^2)]^{1/3} up to a weak r_in-dependent factor, so correlating this f with log(M_BH mdot^2) is a nonlinear transformation of the observed relation between n_e,obs and M_BH mdot^2 rather than an independent prediction. The paper itself finds no anti-correlation between log n_e and log(M_BH mdot^2) (Fig. 8, §4.4), whereas the fixed-f SS73 model predicts exactly log n_e = −log(M_BH mdot^2) + const; a null slope is therefore a disconfirmation of the fixed-f prediction, and allowing f to vary per source absorbs that failure by construction. Consequently, the reported ρ_s = 0.73 (p = 0.01) is a mathematical consequence of the inversion, not evidence for the variable-f α-disk model. A valid test requires either independent physics predicting f, a simulation of the null distribution of ρ_s under f = const using the measured n_e uncertainties, or statistics based on quantities not already used in the inversion. As written, the statements in the abstract and §5 that the variable-f α-disk model is validated are unsupported.
  2. [§4.4, Eq. (1), Fig. A6] The identification of the relxillCp-fitted density with the SZ94 local density at a single radius r = 10 r_s is assumed without independent justification. relxillCp is computed for a constant-density atmosphere, whereas the SZ94 density is radius-dependent; the observed reflection spectrum is a disk-integrated quantity, so the fitted n_e need not equal the local density at any one radius. The statement that "the point of agreement between the model and measured density is found to be at r = 10 rs for all sources" cannot carry the weight placed on it: since f is free and (1−f)^{-3} spans six orders of magnitude, the model family can be brought into agreement at any chosen radius. The choices r = 10 r_s, α = 0.1, and the fixed emissivity profile (q_out = 3, r_br = 6 r_g) therefore directly determine the reported f values in Table 3 and the sample median f ≈ 0.7, and the abstract's median f = 0.68 inherits these assumptions. If the reflection density is a flux-weighted average over a density gradient, or if the reflection zone is not radiation-pressure dominated, the derived f values and the f–log(M_BH mdot^2) correlation collapse.
  3. [Table 3, Fig. 9] The correlation test treats censored, asymmetric f values as point measurements. Four of the eleven f values in Table 3 are upper limits (UGC 6728, Mrk 1310, NGC 4748, PG 1426+015) and one is a lower limit (PG 1229+204). In addition, the quoted f uncertainties propagate only the n_e uncertainties, not the large errors on the input mdot and M_BH (Table 1: e.g., UGC 6728 has mdot = 0.58^{+0.76}_{−0.21} and PG 0844+349 has log n_e = 18.1^{+0.5}_{−2.1}). Because (1−f)^{-3} ∝ M_BH mdot^2, the input-parameter uncertainties translate into f uncertainties comparable to or larger than the reported ranges, and these same parameters appear in the independent variable X, further coupling the test to the inversion. With N = 11, heavy censoring, and asymmetric posteriors, the reported ρ_s = 0.73, p = 0.01 does not establish the claimed correlation; a censored-data treatment with full posterior propagation is needed before any correlation claim can be made.
minor comments (5)
  1. [Abstract vs. §4.1, Table 2, Appendix A] The arXiv abstract states that pure high-density reflection fits "3 out of 11 AGN" with warm Comptonization required for the remaining sources, whereas the full-text abstract, the body text, Table 2, and the per-source appendices consistently find the opposite (8/11 fitted by reflection alone; 3/11 — NGC 4748, Mrk 110, PG 1426+015 — requiring additional warm Comptonization). The abstract inverts the headline soft-excess result and must be corrected.
  2. [Abstract (both versions)] The manuscript contains two different abstracts with inconsistent median values (f = 0.68 vs 0.7; hot-corona kTe = 54 vs 63 keV; τe = 0.98 vs 0.85). The body text (§4.4 and §4.5) matches the full-text abstract; the two versions should be reconciled before publication.
  3. [Eq. (2), §4.5] Equation (2) as typeset places the "−1.5" term inside the square root: τe = √(2.25 + 3(kTe/mec^2)[(Γ+0.5)^2 − 2.25] − 1.5). In the standard form of this expression the −1.5 sits outside the radical; as printed, the inferred optical depths shift by roughly a unit and the median τe = 0.85 quoted in §4.5 is not reproducible from the stated kTe and Γ values. Please fix the formula and recompute the τe distribution.
  4. [§4.6, Fig. 13] The three sources for which spin is claimed to be measured for the first time (UGC 6728, Mrk 1310, PG 1426+015) have weakly constrained values (a* = 0.73^{+0.11}_{−0.61}, 0.9^{+0.07}_{−0.70}, 0.44^{+0.49}_{−0.12}, respectively), and the claim of a "~20% increase in the spin census" should be qualified accordingly.
  5. [§4.4 and abstract] The phrases "first-ever calculation" and "for the first time in any accreting objects" concerning f are over-claims. f is obtained by rearranging an existing analytic formula (SZ94) under assumed parameter choices; the genuinely new element is the systematic application to a sample, and the text should be worded as such.

Circularity Check

1 steps flagged · score 7.0 of 10

The f–log(MBH ṁ^2) correlation is an inversion artifact, not an independent validation of the α-disk model.

  1. fitted input called prediction [Section 4.4, Eq. (1), Figs. 8–9, Table 3]
    "ne = 1/(σT rs) (256√2/27) α^{-1} r^{3/2} ṁ^{-2} [1-(rin/r)^{1/2}]^{-2} (1-f)^{-3} ... We calculate the f-values from the measured disk density at r = 10 rs for each source using equation (1) ... As it stands, we have taken care of all the model intrinsic scatters involved, and if the standard α-disk model is valid, we expect a correlation between f and log[MBH ṁ2]. ..."

    Equation (1) is inverted to solve for f from the fitted density ne and the same MBH and ṁ that define X = MBH ṁ^2. Setting α = 0.1 and r = 10 rs, the inversion gives f = 1 − [C'/(ne X)]^{1/3} up to a weak rin-dependent factor. Thus f is not an independent observable: it is a deterministic function of the measured ne and the same X used in the correlation. The paper explicitly reports no anti-correlation between log ne and log X (Fig. 8)—the actual fixed-f SS73 prediction—and then converts the residuals into f. With log ne approximately independent of log X, the transformation log(1−f) = −(1/3)(log ne + log X) + const automatically produces a positive f−X correlation. The claimed validation therefore restates the input inversion rather than testing a model prediction.

full rationale

The central validation claim in Section 4.4 reduces by construction. Equation (1) is the defining relation used to compute f from the spectral-fit density and the same black-hole-mass and accretion-rate variables that appear in the claimed correlation, so the f versus log(MBH ṁ^2) correlation is a transformed plot of the inputs, not an independent test of the variable-f α-disk model. The paper acknowledges the absence of the fixed-f predicted log ne–log X anti-correlation, then absorbs that failure into per-source f values and presents the resulting correlation as validation; this is a fitted-input-called-prediction pattern. The other principal results—DIC-based model selection for the soft X-ray excess, coronal temperature/optical-depth comparisons with external literature, and spin measurements validated against prior broadband spectroscopy—are self-contained spectral modeling exercises with independent benchmark comparisons and show no circularity. There is no load-bearing self-citation chain; self-citations to Mallick et al. (2022) and JJ19 provide data and context rather than forcing the f-inversion. Overall score 7: the manuscript contains substantial independent analysis, but its headline disk-to-corona power-transfer fraction validation is circular by inversion.

Assumptions & free parameters 5 free parameters · 5 assumptions · 0 invented entities

The central derived quantity f rests on the assumed SZ94 formula, fixed alpha = 0.1 and r = 10 r_s, and on the mapping between the reflection-model density and the local disk density. These assumptions are not independently tested in the paper, and the validation correlation follows algebraically from them.

free parameters (5)
  • Disk electron density log n_e = 15 to 20 per source, e.g., Mrk 110: 18.0^{+1.5}_{-0.3}
    Fitted to the broadband spectra with relxillCp; it directly determines the derived f values through Eq. (1).
  • Viscosity parameter alpha = 0.1 (fixed)
    Assumed in Eq. (1) to convert measured density to f; not varied in the paper, so systematic error on f is underestimated.
  • Disk radius r for f evaluation = 10 r_s (fixed)
    The f values are evaluated at r = 10 r_s because 'the point of agreement' was found there; no uncertainty is propagated for this choice.
  • Emissivity break radius r_br = 6 r_g (fixed)
    Fixed in the reflection model as 'a typical value' from Mallick et al. 2021, 2022; affects spin and density constraints.
  • Seed photon temperature = 50 eV (fixed)
    Assumed in relxillCp and nthComp; affects the continuum shape and thus the derived densities.
assumptions (5)
  • domain assumption SZ94 density formula (Eq. 1) for a radiation-pressure-dominated inner disk
    The paper uses this relation to convert measured n_e into f; the formula itself assumes the standard α-disk model, so using its success as validation is circular.
  • domain assumption The α-disk model (SS73) structure applies to the inner disk of these AGN
    The paper claims to test the standard α-disk model but assumes it in Eq. (1) to derive f.
  • domain assumption relxillCp reflection model correctly predicts soft excess, Fe K line and Compton hump for dense disks
    The central spectral conclusions rely on the accuracy of this publicly available table model, including its broken power-law emissivity assumption.
  • ad hoc to paper Broken power-law emissivity with qout = 3 and r_br = 6 r_g
    The emissivity profile is assumed, with the break radius fixed to 6 r_g based on prior self-cited work; this affects the measured spin.
  • ad hoc to paper The measured reflection density corresponds to the SZ94 local density at a single radius
    The reflection model yields a density parameter that is not necessarily the local density at r = 10 r_s; this mapping is assumed without independent justification.

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Cite this review

Pith. "Pith review of Constraining Disk-to-Corona Power Transfer Fraction, Soft X-ray Excess Origin, and Black Hole Spin Population of Type-1 AGN across Mass Scales." pith.science (2026). https://pith.science/paper/ELSGJPZL

@misc{pith2026250115380,
  author       = {Pith},
  title        = {Pith review of: Constraining Disk-to-Corona Power Transfer Fraction, Soft X-ray Excess Origin, and Black Hole Spin Population of Type-1 AGN across Mass Scales},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/ELSGJPZL}},
  note         = {Machine review of arXiv:2501.15380}
}
abstract

Understanding the nature of the accretion disk, its interplay with the X-ray corona, and assessing black hole spin demographics remain open challenges in astrophysics. In this paper, we examine the predictions of the standard $\alpha$-disk model, origin of the puzzling soft X-ray excess, and measure the black hole spin parameter by applying an updated high-density disk reflection model to the XMM-Newton/NuSTAR broadband (0.3$-$78 keV) X-ray spectra of a sample of 11 Type-1 AGN. Our Bayesian analysis confirms that a variable-density relativistic disk reflection model with a broken power-law emissivity profile can simultaneously fit the soft X-ray excess, broad iron K line emission, and Compton hump in 3 out of 11 AGN. For the remaining sources, a distinct warm Comptonization component is still required, which supports a hybrid origin for the soft X-ray excess. The measured temperature and optical depth of the warm corona span nearly the entire theoretically allowed range, with median values of $0.43_{-0.18}^{+0.40}$ keV and $12.5_{-3.9}^{+3.1}$, respectively. Our first systematic calculation of the disk-to-corona power transfer fraction reveals that the fraction of power released from the accretion disk into the hot corona spans a wide range, with a sample median of $0.68_{-0.25}^{+0.25}$. The sample median values for the hot coronal plasma temperature and optical depth are $54_{-12}^{+11}$ keV and $0.98_{-0.28}^{+0.22}$, respectively. Finally, through both hard X-ray (3$-$78 keV) and broadband (0.3$-$78 keV) relativistic reflection spectroscopy, we systematically constrain the black hole spin parameter across the mass scales of $\log(M_{\rm BH}/M_{\odot}) \sim 5.5-9.0$, thereby increasing or refining the available spin measurements in the AGN population by $\sim$20%.

Figures

Figures reproduced from arXiv: 2501.15380 by the authors.

Figure 1
Figure 1. Distribution of black hole mass (left panel) and dimensionless mass accretion rate (right panel) of the AGN sample employed in this work [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. The flowchart depicts our step-by-step spectral fitting methodology, which unambiguously probes the origin of the soft X-ray excess in the sample containing diverse spectral features. 0.3−78 keV energy range. The XMM-Newton EPIC￾pn (MOS for UGC 6728) and NuSTAR FPMA/B spectral data, the Galactic absorption corrected power-law contin￾uum model, and data-to-model ratio plots for the sample are shown in Fig. A1. The ra… view at source ↗
Figure 3
Figure 3. The flux of the relativistic reflection (relxillCp) model versus non-relativistic or distant reflection (either zGauss[Narrow] or xillverCp) model relative to the primary continuum (nthComp) flux in the 5−7 keV band, demon￾strating the relative contributions of the relativistic and distant reflection components in the Fe K band. The 1 : 1 line represents  Frelativistic reflection Fprimary continnum  [5−7 keV] =  … view at source ↗
Figures from the paper (11 more)
Figure 4
Figure 4. Figure 4: The left panel shows the spectra calculated by the relativistic reflection model, relxillCp, for a range of disk densities, log[ne/cm−3 ] = 15, 16, 17, 18, 19, and 20. The standard model parameters are assumed to be Γ = 2, kTe = 300 keV, ξ = 500 erg cm s−1 , qin = 8, a…
Figure 5
Figure 5. Figure 5: The left panel shows the distribution of the measured electron density of the accretion disk for our sample. The colorbar in the right panel depicts the difference between the Deviance Information Criteria, DICwithout WC and DICwith WC, for the variable density disk re…
Figure 6
Figure 6. Figure 6: The left panel shows the variation in relativistic disk reflected flux with the directly observed continuum flux in the 0.3–50 keV range. The solid black line depicts the best-fit model and has the form FrelxillCp[0.3−50 keV] ∝ F 0.63±0.15 nthComp[0.3−50 keV]. The vari…
Figure 7
Figure 7. Figure 7: Comparison of disk density, iron abundance, black hole spin, and disk inclination angle obtained from our broadband (0.3– 78 keV) joint XMM-Newton+NuSTAR spectral modeling and the previous 0.5–10 keV XMM-Newton spectral fitting of the sample by JJ19. For UGC 6728, Mrk …
Figure 8
Figure 8. Figure 8: Theoretically, the electron density (ne) of the accretion disk depends on five parameters: MBH, m˙ , f, r, and rin. The left panel shows how the disk density changes as a function of the BH mass times the accretion rate squared, MBHm˙ 2 in logarithmic scale. The densit…
Figure 9
Figure 9. Figure 9: The fraction (f) of power transferred from the disk into the corona, measured at r = 10rs, is plotted as a function of log[MBH m˙ 2 ] and log[MBH/M⊙] in the left panel. We find a strong positive correlation between f and log[MBH m˙ 2 ] with a Spearman rank correlation …
Figure 10
Figure 10. Figure 10: Comparison of the electron temperature (blue circles) of hot corona obtained from our broadband XMM￾Newton+NuSTAR spectral modeling of the sample and their previous measurements (orange diamonds) from the literature (Ricci et al. 2017; Akylas & Georgantopoulos 2021; P…
Figure 11
Figure 11. Figure 11: Distribution of measured temperature (kTe) and inferred optical depth (τe) of the hot corona for 11 AGN from this work. The median values of hot coronal temperature and optical depth for the sample are kTe = 63+23 −11 keV and τe = 0.85+0.12 −0.27, respectively. 1.8 2.…
Figure 12
Figure 12. Figure 12: Disk-to-corona power transfer fraction (f) as a function of the photon index (Γ) of the primary continuum. A moderate pos￾itive correlation exists between the f-parameter and photon index, which can be explained in the context of inverse-Compton scatter￾ing of disk ph…
Figure 13
Figure 13. Figure 13: Evolution of dimensionless black hole spin as a function of black hole mass constructed using the most updated spin and mass measurements. The red squares show the spin measurements of the 11 AGN from this work. The green squares and blue triangles denote the spin mea…
Figure 14
Figure 14. Figure 14: Distribution of black hole spin for 11 AGN from this work and all 60 AGN with updated spin measurements, including those 11 AGN. Our spin measurements increase the spin population by ∼ 20%. where, Z1 = 1 + (1 − a ∗2 ) 1/3 h (1 + a ∗ ) 1/3 + (1 − a ∗ ) 1/3 i , (5) Z2 =…

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Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. OpenAlex reports about 2 citations worldwide. Full citation record

  1. A possible two-fold scenario for the disc-corona of the luminous AGN 1H 0419--577: a high-density disc or a warm corona

    astro-ph.HE 2025-06 conditional novelty 6.0 of 10

    Two competing disc-corona models, a high-density disc and a warm corona plus reflection, both fit the 2018 broadband X-ray spectra of the luminous AGN 1H 0419-577 equally well.

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