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arxiv: 2602.12548 · v2 · pith:ZZKEUXLKnew · submitted 2026-02-13 · 🌌 astro-ph.GA

The Structure and Evolution of LRDs: Insights from JWST NIRSpec Medium and High Resolution Spectroscopy at zsim4

Yuxuan Pang , Xin Wang , Cheng Cheng , Shengzhe Wang , Hang Zhou , Qianqiao Zhou , Xue-Bing Wu , Karl Glazebrook This is my paper

Pith reviewed 2026-05-21 13:12 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords little red dotsJWST NIRSpec spectroscopybroad Hα linesactive galactic nucleiblack hole massesclumpy envelope modelhigh-redshift galaxiesEddington ratios
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The pith

Broad Hα luminosity correlates with optical continuum in z~4 little red dots, indicating a shared AGN origin and yielding black hole masses of 10^6-10^8 solar masses.

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

This paper decomposes Balmer lines in JWST medium- and high-resolution spectra of eleven little red dots at redshift around four. It finds that broad Hα strength tracks the optical continuum closely but shows no such link to the ultraviolet light, which points to a common active galactic nucleus origin for the optical emission and the line. From the broad line width and luminosity the authors derive central black hole masses between one million and one hundred million solar masses accreting at Eddington ratios near 0.6. They introduce a clumpy envelope model in which the optical light comes from an extended, clumpy gas region tens of light-days across whose radial temperature gradients and self-absorption produce the observed continuum shapes. The work places these objects in an early, rapid-growth phase that may later become narrow-line Seyfert 1 galaxies.

Core claim

The broad Hα luminosity strongly correlates with the optical continuum but not with the UV, indicating a common AGN origin for both. Using the width and luminosity of the broad Hα line, central black hole masses of 10^6-10^8 M⊙ accreting at high Eddington ratios are estimated. A Clumpy Envelope model is proposed in which the optical emission arises from an extended, clumpy gas with a characteristic radius of tens of light-days, with diversity in continuum shapes explained by radial temperature gradients and self-absorption effects.

What carries the argument

The Clumpy Envelope model: an extended, clumpy gas structure with characteristic radius of tens of light-days that produces the observed optical emission through radial temperature gradients and self-absorption.

If this is right

  • Assuming constant mass accretion in slim-disk models, the objects have growth timescales of roughly 10^5 to 10^7 years.
  • LRDs may evolve into narrow-line Seyfert 1 galaxies.
  • LRDs exhibit intrinsically weak optical Fe II emission relative to typical AGN.
  • The variety of observed optical continuum shapes is produced by radial temperature gradients and self-absorption within the clumpy gas.

Where Pith is reading between the lines

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

  • If the clumpy envelope accounts for the optical properties, similar structures could be searched for via continuum variability in other high-redshift AGN.
  • The inferred rapid accretion phase implies these objects contribute to the early assembly of the supermassive black hole population seen today.
  • Future independent mass checks, such as from dynamical modeling or X-ray observations, would test whether local virial calibrations hold at z~4.

Load-bearing premise

The black hole masses and Eddington ratios are derived by applying standard virial relations calibrated on local AGN directly to the width and luminosity of the broad Hα line.

What would settle it

Reverberation mapping that measures a broad-line region size inconsistent with tens of light-days, or a larger sample showing no correlation between broad Hα luminosity and optical continuum, would undermine the common AGN origin and mass estimates.

Figures

Figures reproduced from arXiv: 2602.12548 by Cheng cheng, Hang Zhou, Karl Glazebrook, Qianqiao Zhou, Shengzhe Wang, Xin Wang, Xue-Bing Wu, Yuxuan Pang.

Figure 1
Figure 1. Figure 1: Spectral fitting results for the Hα emission lines in our LRD sample. In each panel, the black histogram represents the observed 1D flux density fν (in units of µJy), the gray shaded region indicates its 1σ uncertainty, and the best fitting total model is shown as the solid red line. The broad and narrow emission-line components are depicted by the green and blue dashed curves, respectively. The source ID … view at source ↗
Figure 2
Figure 2. Figure 2: Spectral fitting results for the Hβ and [O III] emission lines in our LRD sample. The line components, labels, and annotations are the same as [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: The flux of the broad Hα component, the narrow Hα component, and the [O III]λ5007 emission line as a function of rest-frame UV and optical luminosities from de Graaff et al. (2025b) in our LRD sample. Spearman correlation coefficients and p-values are indicated in each panel. The broad Hα flux shows a strong correlation with the optical luminosity but exhibits no significant correlation with the UV magnitu… view at source ↗
Figure 4
Figure 4. Figure 4: Distribution of LRDs and AGNs on the FWHMHα–λEdd plane. Our LRD sample is shown as black filled circles. Other known LRDs from Labbe et al. (2024); de Graaff et al. (2025a); Naidu et al. (2025); Wang et al. (2025); Taylor et al. (2025a); Ji et al. (2025) are indicated by colored squares (using the same method from Hα line in this work to estimate the λEdd). Recently identified candidates in a possible tran… view at source ↗
Figure 5
Figure 5. Figure 5: Distribution of LRDs and AGNs on the FWHMHα–RFeII plane. Upper limits for our LRD sample are plotted as black filled dots, while predicted RFeII values based on the λEdd − RFeII relation from the QSO sample in Pan et al. (2025) are indicated by open black dots. Results from other literature studies with Fe line fitting are sum￾marized as squares (Labbe et al. 2024; Torralba et al. 2025; Tripodi et al. 2025… view at source ↗
Figure 6
Figure 6. Figure 6: Schematic illustration of our proposed gas shell structure for LRDs. Compared to the cocoon envelope model originally proposed by Naidu et al. (2025), our model suggests a larger physical size and lower covering factor in each layer of the cocoon envelope. Compared to the black hole star model of Inayoshi et al. (2025), our model possesses a thicker photosphere, with a temperature that gradually decreases … view at source ↗
Figure 7
Figure 7. Figure 7: Physical origins and interpretations of the LRD optical continuum shape. Upper panel: Influence of ex￾tinction and gas shell thickness. The black solid curve rep￾resents the standard blackbody emission for Teff = 5000K. The blue curve shows the same blackbody spectrum after applying an extinction of AV = 1 assuming the extinction law from Fitzpatrick (1999), which does not differ signifi￾cantly from a cool… view at source ↗
Figure 8
Figure 8. Figure 8: Redshift evolution of the black hole to stellar mass ratio (MBH/M∗). LRD sources from this work are plot￾ted as stars. Filled squares denote recently identified JWST selected normal AGNs and LRDs (Goulding et al. 2023; Lar￾son et al. 2023; Kocevski et al. 2023; Harikane et al. 2023; Bogd´an et al. 2024; Wang et al. 2024; Furtak et al. 2024; Kokorev et al. 2024b; Maiolino et al. 2024; Juodˇzbalis et al. 202… view at source ↗
read the original abstract

We present an analysis of medium/high-resolution JWST/NIRSpec spectra for 11 LRDs at $z \sim 4$. By decomposing the broad and narrow components of the Balmer emission lines, we investigate the connection between line emission and UV/optical continua for the LRD population. We find that the broad H$\alpha$ luminosity strongly correlates with the optical continuum (but not with the UV), indicating a common AGN origin for both. In contrast, the [O III] line strength is correlated with the UV continuum rather than the optical. Using the width and luminosity of the broad H$\alpha$ line, we estimate central black hole masses of $10^6-10^8 M_{\odot}$ accreting at high Eddington ratios, consistent with an early ($\lambda_{\rm Edd} \sim 0.6$), rapid-growth phase of AGN evolution. Assuming a constant mass accretion rate in the framework of slim-disk models, we infer growth timescales of $\sim 10^5-10^7\rm yr$, and suggest LRDs may evolve into narrow-line Seyfert 1 galaxies. Upper limits from our spectra indicate that LRDs exhibit intrinsically weak optical Fe II emission compared to typical AGN. To simultaneously account for the inferred broad-line region size and observed luminosity, we propose a "Clumpy Envelope" model in which the optical emission arises from an extended, clumpy gas with a characteristic radius of tens of light-days. The diversity in observed optical continuum shapes can be explained by radial temperature gradients and self-absorption effects within this structure. Our results demonstrate the power of JWST high-resolution spectroscopy in probing the central engines and physical nature of the LRD population.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript analyzes medium- and high-resolution JWST/NIRSpec spectra of 11 Little Red Dots (LRDs) at z ≈ 4. By decomposing broad and narrow Balmer line components, it reports a strong correlation between broad Hα luminosity and the optical continuum (but not UV), indicating a common AGN origin. Central black hole masses of 10^6–10^8 M_⊙ accreting at λ_Edd ≈ 0.6 are estimated via virial relations on the broad Hα, yielding growth timescales of ~10^5–10^7 yr under constant accretion in slim-disk models. A 'Clumpy Envelope' model is proposed in which optical emission arises from extended clumpy gas at radii of tens of light-days, with diversity in continuum shapes attributed to radial temperature gradients and self-absorption. LRDs are suggested to evolve into narrow-line Seyfert 1 galaxies, and upper limits on optical Fe II are noted.

Significance. If the virial mass estimates can be shown to be robust against high-redshift systematics and the clumpy envelope model is developed with testable quantitative predictions, the work would provide valuable spectroscopic constraints on early supermassive black hole growth and the physical structure of the LRD population. The use of NIRSpec medium/high-resolution data for line decomposition and continuum correlation analysis is a clear observational strength.

major comments (2)
  1. [Abstract and §4.2] Abstract and §4.2 (Black Hole Mass Estimates): The headline masses (10^6–10^8 M_⊙) and Eddington ratios (λ_Edd ~0.6) rest on direct application of the local virial estimator M_BH ∝ L_Hα^{0.5} × FWHM_Hα^2 with standard zero-point and f-factor. This is load-bearing for the growth timescale and evolutionary claims, yet the text provides no discussion of possible systematic offsets in BLR radius-luminosity relation, geometry, or non-virial motions at z~4 within the proposed clumpy envelope. No uncertainty quantification or independent mass anchor is given, rendering the numerical values extrapolations.
  2. [§5] §5 (Clumpy Envelope Model): The model is introduced to reconcile the inferred BLR size with observed luminosity and to explain continuum diversity via temperature gradients and self-absorption. However, it remains qualitative; no specific predictions (e.g., expected line profiles, radial temperature law, or synthetic spectra) are derived or compared to the NIRSpec observations, limiting its ability to be tested or falsified with the current data.
minor comments (2)
  1. [Abstract] Abstract: Correlations are stated as 'strong' without reporting correlation coefficients, p-values, or error bars on derived quantities such as masses and timescales.
  2. [Throughout] Notation: Ensure uniform use of λ_Edd (or λ_Edd) and clarify the exact assumptions entering the slim-disk growth timescale calculation.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their detailed and constructive report on our manuscript analyzing JWST/NIRSpec spectra of Little Red Dots at z~4. The comments on the robustness of the black hole mass estimates and the development of the clumpy envelope model are well taken. We address each point below and have revised the manuscript to incorporate additional discussion and clarifications while preserving the core observational results.

read point-by-point responses

  1. Referee: [Abstract and §4.2] Abstract and §4.2 (Black Hole Mass Estimates): The headline masses (10^6–10^8 M_⊙) and Eddington ratios (λ_Edd ~0.6) rest on direct application of the local virial estimator M_BH ∝ L_Hα^{0.5} × FWHM_Hα^2 with standard zero-point and f-factor. This is load-bearing for the growth timescale and evolutionary claims, yet the text provides no discussion of possible systematic offsets in BLR radius-luminosity relation, geometry, or non-virial motions at z~4 within the proposed clumpy envelope. No uncertainty quantification or independent mass anchor is given, rendering the numerical values extrapolations.

    Authors: We agree that a more explicit discussion of potential high-redshift systematics is needed to strengthen the presentation. In the revised §4.2 we have added a dedicated paragraph noting that the local R-L relation and virial factor may evolve at z~4, particularly if the BLR geometry differs within the proposed clumpy envelope. We cite recent high-z AGN studies that explore similar offsets and emphasize that our mass estimates should be viewed as order-of-magnitude indicators rather than precise values. We also report the propagated uncertainties from the line measurements and explicitly state the absence of independent mass anchors for this population. These additions do not alter the reported growth timescales but place them in appropriate context. revision: yes

  2. Referee: [§5] §5 (Clumpy Envelope Model): The model is introduced to reconcile the inferred BLR size with observed luminosity and to explain continuum diversity via temperature gradients and self-absorption. However, it remains qualitative; no specific predictions (e.g., expected line profiles, radial temperature law, or synthetic spectra) are derived or compared to the NIRSpec observations, limiting its ability to be tested or falsified with the current data.

    Authors: The clumpy envelope is offered as an interpretive framework motivated by the observed line-continuum correlations and the inferred BLR radii. We acknowledge that it is currently qualitative. In the revised §5 we now include a simple illustrative radial temperature gradient (T ∝ r^{-0.5}) and describe how self-absorption and clump covering factors could produce the range of observed optical slopes. We also outline two observable predictions: (1) a correlation between continuum redness and broad-line asymmetry that could be tested with higher-S/N spectra, and (2) the expected suppression of high-ionization lines relative to Balmer lines. Full radiative-transfer synthetic spectra lie beyond the scope of this observational work but are flagged as a natural next step. revision: partial

Circularity Check

0 steps flagged

No significant circularity; estimates apply external calibrations to new data

full rationale

The paper measures broad Hα properties from JWST spectra, applies the standard virial mass estimator (external local-AGN calibration) to obtain 10^6-10^8 M⊙ values, computes Eddington ratios from observed luminosity and those masses, and infers growth times under constant-accretion slim-disk assumptions. The Clumpy Envelope model is introduced as a new proposal to reconcile the resulting BLR size with the observed optical luminosity and continuum shapes. None of these steps reduce by construction to the paper's own inputs or prior self-citations; all rest on independently established relations and the fresh spectroscopic dataset. The derivation chain is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 1 invented entities

The analysis depends on standard AGN spectroscopic assumptions and introduces a novel structural model for LRDs.

free parameters (2)
  • Eddington ratio λ_Edd = ~0.6
    Estimated for the LRD sample from broad line properties.
  • Characteristic radius of clumpy gas = tens of light-days
    Inferred to match broad-line region size and luminosity.
axioms (2)
  • domain assumption Virial theorem applies to estimate black hole mass from broad Hα width and luminosity
    Used to derive masses of 10^6-10^8 M_⊙
  • domain assumption Slim-disk models with constant mass accretion rate
    For calculating growth timescales of 10^5-10^7 yr
invented entities (1)
  • Clumpy Envelope no independent evidence
    purpose: Explains the optical continuum and broad line region as arising from extended clumpy gas
    New model proposed to account for observed properties without prior independent confirmation

pith-pipeline@v0.9.0 · 5884 in / 1696 out tokens · 77927 ms · 2026-05-21T13:12:27.721476+00:00 · methodology

discussion (0)

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Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Paschen Jumps in Little Red Dots: Evidence for Nebular Continua

    astro-ph.GA 2026-04 unverdicted novelty 6.0

    Paschen jumps in Little Red Dots indicate their continua originate from free-bound recombination emission in low-temperature nebular gas rather than thermalized or AGN components.

  2. Halo-driven Origin and Suppression of Over-massive Black Holes and Little Red Dots

    astro-ph.GA 2026-05 unverdicted novelty 5.0

    Halo-driven transient rapid growth followed by thermodynamic suppression explains over-massive black holes and Little Red Dots as precursors to standard SMBH-galaxy coevolution.

Reference graph

Works this paper leans on

110 extracted references · 110 canonical work pages · cited by 2 Pith papers · 10 internal anchors

  1. [1]

    B., Casey, C

    Akins, H. B., Casey, C. M., Lambrides, E., et al. 2025a, ApJ, 991, 37, doi: 10.3847/1538-4357/ade984

    work page doi:10.3847/1538-4357/ade984

  2. [2]

    B., Casey, C

    Akins, H. B., Casey, C. M., Berg, D. A., et al. 2025b, ApJL, 980, L29, doi: 10.3847/2041-8213/adab76

    work page doi:10.3847/2041-8213/adab76 2041

  3. [3]

    T., Bogd´ an,´A., Kov´ acs, O

    Ananna, T. T., Bogd´ an,´A., Kov´ acs, O. E., Natarajan, P., & Hickox, R. C. 2024, ApJL, 969, L18, doi: 10.3847/2041-8213/ad5669

    work page doi:10.3847/2041-8213/ad5669 2024

  4. [4]

    1993, ARA&A, 31, 473, doi: 10.1146/annurev.aa.31.090193.002353

    Antonucci, R. 1993, ARA&A, 31, 473, doi: 10.1146/annurev.aa.31.090193.002353

    work page doi:10.1146/annurev.aa.31.090193.002353 1993

  5. [5]

    Origins of the UV continuum and Balmer emission lines in Little Red Dots: observational validation of dense gas envelope models enshrouding the AGN

    Asada, Y., Inayoshi, K., Fei, Q., Fujimoto, S., & Willott, C. 2026, arXiv e-prints, arXiv:2601.10573, doi: 10.48550/arXiv.2601.10573

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2601.10573 2026

  6. [6]

    Baggen, J. F. W., van Dokkum, P., Brammer, G., et al. 2024, ApJL, 977, L13, doi: 10.3847/2041-8213/ad90b8

    work page doi:10.3847/2041-8213/ad90b8 2024

  7. [7]

    1995, ApJL, 455, L119, doi: 10.1086/309827

    Baldwin, J., Ferland, G., Korista, K., & Verner, D. 1995, ApJL, 455, L119, doi: 10.1086/309827

    work page doi:10.1086/309827 1995

  8. [8]

    A., Ferland, G

    Baldwin, J. A., Ferland, G. J., Korista, K. T., Hamann, F., & LaCluyz´ e, A. 2004, ApJ, 615, 610, doi: 10.1086/424683

    work page doi:10.1086/424683 2004

  9. [9]

    G., Kocevski, D

    Barro, G., P´ erez-Gonz´ alez, P. G., Kocevski, D. D., et al. 2024, ApJ, 963, 128, doi: 10.3847/1538-4357/ad167e

    work page doi:10.3847/1538-4357/ad167e 2024

  10. [10]

    G., Kocevski, D., et al

    Barro, G., Perez-Gonzalez, P. G., Kocevski, D., et al. 2025, arXiv e-prints, arXiv:2512.15853, doi: 10.48550/arXiv.2512.15853

    work page doi:10.48550/arxiv.2512.15853 2025

  11. [11]

    C., & Dexter, J

    Begelman, M. C., & Dexter, J. 2026, ApJ, 996, 48, doi: 10.3847/1538-4357/ae274a Bogd´ an,´A., Goulding, A. D., Natarajan, P., et al. 2024, Nature Astronomy, 8, 126, doi: 10.1038/s41550-023-02111-9

    work page doi:10.3847/1538-4357/ae274a 2026

  12. [12]

    2010, A&A, 510, A56, doi: 10.1051/0004-6361/200913229

    Bongiorno, A., Mignoli, M., Zamorani, G., et al. 2010, A&A, 510, A56, doi: 10.1051/0004-6361/200913229

    work page doi:10.1051/0004-6361/200913229 2010

  13. [13]

    A., & Green, R

    Boroson, T. A., & Green, R. F. 1992, ApJS, 80, 109, doi: 10.1086/191661

    work page doi:10.1086/191661 1992

  14. [14]

    J., Curtis-Lake, E., et al

    Boyett, K., Bunker, A. J., Curtis-Lake, E., et al. 2024, MNRAS, 535, 1796, doi: 10.1093/mnras/stae2430

    work page doi:10.1093/mnras/stae2430 2024

  15. [15]

    2023, msaexp: NIRSpec analyis tools, 0.6.17, Zenodo, doi: 10.5281/zenodo.8319596

    Brammer, G. 2023, msaexp: NIRSpec analyis tools, 0.6.17, Zenodo, doi: 10.5281/zenodo.8319596

    work page doi:10.5281/zenodo.8319596 2023

  16. [16]

    2023, The DAWN JWST Archive: Compilation of Public NIRSpec Spectra, 4.4, Zenodo, doi: 10.5281/zenodo.15472353

    Brammer, G., & Valentino, F. 2023, The DAWN JWST Archive: Compilation of Public NIRSpec Spectra, 4.4, Zenodo, doi: 10.5281/zenodo.15472353

    work page doi:10.5281/zenodo.15472353 2023

  17. [17]

    2026, arXiv e-prints, arXiv:2601.22214, doi: 10.48550/arXiv.2601.22214

    Brazzini, M., D’Eugenio, F., Maiolino, R., et al. 2026, arXiv e-prints, arXiv:2601.22214, doi: 10.48550/arXiv.2601.22214

    work page doi:10.48550/arxiv.2601.22214 2026

  18. [18]

    C., Trump, J

    Brooks, M., Simons, R. C., Trump, J. R., et al. 2025, ApJ, 986, 177, doi: 10.3847/1538-4357/addac4

    work page doi:10.3847/1538-4357/addac4 2025

  19. [19]

    The 6dF Galaxy Survey: Baryon Acoustic Oscillations and the Local Hubble Constant,

    Caccianiga, A., & Severgnini, P. 2011, MNRAS, 415, 1928, doi: 10.1111/j.1365-2966.2011.18838.x LRD Properties & Evolution17

    work page doi:10.1111/j.1365-2966.2011.18838.x 2011

  20. [20]

    M., Akins, H

    Casey, C. M., Akins, H. B., Kokorev, V., et al. 2024, ApJL, 975, L4, doi: 10.3847/2041-8213/ad7ba7

    work page doi:10.3847/2041-8213/ad7ba7 2024

  21. [21]

    M., Akins, H

    Casey, C. M., Akins, H. B., Finkelstein, S. L., et al. 2025, ApJL, 990, L61, doi: 10.3847/2041-8213/adfa91

    work page doi:10.3847/2041-8213/adfa91 2025

  22. [22]

    C., Li, R., & Inayoshi, K

    Chen, C.-H., Ho, L. C., Li, R., & Inayoshi, K. 2025, ApJL, 989, L12, doi: 10.3847/2041-8213/adee0a

    work page doi:10.3847/2041-8213/adee0a 2025

  23. [23]

    JADES Data Release 4 Paper I: Sample Selection, Observing Strategy and Redshifts of the complete spectroscopic sample

    Curtis-Lake, E., Cameron, A. J., Bunker, A. J., et al. 2025, arXiv e-prints, arXiv:2510.01033, doi: 10.48550/arXiv.2510.01033

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2510.01033 2025

  24. [24]

    J., et al

    Dattathri, S., Natarajan, P., Porras-Valverde, A. J., et al. 2025, ApJ, 984, 122, doi: 10.3847/1538-4357/adbeef de Graaff, A., Rix, H.-W., Naidu, R. P., et al. 2025a, A&A, 701, A168, doi: 10.1051/0004-6361/202554681 de Graaff, A., Hviding, R. E., Naidu, R. P., et al. 2025b, arXiv e-prints, arXiv:2511.21820, doi: 10.48550/arXiv.2511.21820 de Graaff, A., Br...

    work page doi:10.3847/1538-4357/adbeef 2025

  25. [25]

    D., et al

    Ding, X., Onoue, M., Silverman, J. D., et al. 2023, Nature, 621, 51, doi: 10.1038/s41586-023-06345-5

    work page doi:10.1038/s41586-023-06345-5 2023

  26. [26]

    C., Yuan, W., et al

    Dong, X.-B., Ho, L. C., Yuan, W., et al. 2012, ApJ, 755, 167, doi: 10.1088/0004-637X/755/2/167

    work page doi:10.1088/0004-637x/755/2/167 2012

  27. [27]

    2018, ApJ, 856, 6, doi: 10.3847/1538-4357/aaae6b

    Du, P., Zhang, Z.-X., Wang, K., et al. 2018, ApJ, 856, 6, doi: 10.3847/1538-4357/aaae6b

    work page doi:10.3847/1538-4357/aaae6b 2018

  28. [28]

    Overview of the JWST Advanced Deep Extragalactic Survey (JADES)

    Eisenstein, D. J., Willott, C., Alberts, S., et al. 2023, arXiv e-prints, arXiv:2306.02465, doi: 10.48550/arXiv.2306.02465

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2306.02465 2023

  29. [29]

    Fitzpatrick, E. L. 1999, PASP, 111, 63, doi: 10.1086/316293

    work page doi:10.1086/316293 1999

  30. [30]

    2025, arXiv e-prints, arXiv:2512.02096, doi: 10.48550/arXiv.2512.02096

    Fu, S., Zhang, Z., Jiang, D., et al. 2025, arXiv e-prints, arXiv:2512.02096, doi: 10.48550/arXiv.2512.02096

    work page doi:10.48550/arxiv.2512.02096 2025

  31. [31]

    J., Labb´ e, I., Zitrin, A., et al

    Furtak, L. J., Labb´ e, I., Zitrin, A., et al. 2024, Nature, 628, 57, doi: 10.1038/s41586-024-07184-8

    work page doi:10.1038/s41586-024-07184-8 2024

  32. [32]

    J., Duncan, K

    Gloudemans, A. J., Duncan, K. J., Eilers, A.-C., et al. 2025, ApJ, 986, 130, doi: 10.3847/1538-4357/adddb9

    work page doi:10.3847/1538-4357/adddb9 2025

  33. [33]

    D., Greene, J

    Goulding, A. D., Greene, J. E., Setton, D. J., et al. 2023, ApJL, 955, L24, doi: 10.3847/2041-8213/acf7c5

    work page doi:10.3847/2041-8213/acf7c5 2023

  34. [34]

    E., Labbe, I., Goulding, A

    Greene, J. E., Labbe, I., Goulding, A. D., et al. 2024, ApJ, 964, 39, doi: 10.3847/1538-4357/ad1e5f

    work page doi:10.3847/1538-4357/ad1e5f 2024

  35. [35]

    E., Setton, D

    Greene, J. E., Setton, D. J., Furtak, L. J., et al. 2026, ApJ, 996, 129, doi: 10.3847/1538-4357/ae1836

    work page doi:10.3847/1538-4357/ae1836 2026

  36. [36]

    2023, ApJ, 959, 39, doi: 10.3847/1538-4357/ad029e

    Harikane, Y., Zhang, Y., Nakajima, K., et al. 2023, ApJ, 959, 39, doi: 10.3847/1538-4357/ad029e

    work page doi:10.3847/1538-4357/ad029e 2023

  37. [37]

    E., Brammer, G

    Heintz, K. E., Brammer, G. B., Watson, D., et al. 2025, A&A, 693, A60, doi: 10.1051/0004-6361/202450243

    work page doi:10.1051/0004-6361/202450243 2025

  38. [38]

    2025, ApJ, 988, 234, doi: 10.3847/1538-4357/adeb6a

    Hoshi, A., & Yamada, T. 2025, ApJ, 988, 234, doi: 10.3847/1538-4357/adeb6a

    work page doi:10.3847/1538-4357/adeb6a 2025

  39. [39]

    2024, ApJ, 969, 11, doi: 10.3847/1538-4357/ad414c

    Nagao, T. 2024, ApJ, 969, 11, doi: 10.3847/1538-4357/ad414c

    work page doi:10.3847/1538-4357/ad414c 2024

  40. [40]

    E., de Graaff, A., Miller, T

    Hviding, R. E., de Graaff, A., Miller, T. B., et al. 2025, A&A, 702, A57, doi: 10.1051/0004-6361/202555816

    work page doi:10.1051/0004-6361/202555816 2025

  41. [41]

    2025, ApJL, 980, L27, doi: 10.3847/2041-8213/adaebd

    Inayoshi, K., & Maiolino, R. 2025, ApJL, 980, L27, doi: 10.3847/2041-8213/adaebd

    work page doi:10.3847/2041-8213/adaebd 2025

  42. [42]

    Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts

    Inayoshi, K., Murase, K., & Kashiyama, K. 2025, arXiv e-prints, arXiv:2509.19422, doi: 10.48550/arXiv.2509.19422

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2509.19422 2025

  43. [43]

    2025, MNRAS, 544, 3900, doi: 10.1093/mnras/staf1867

    Ji, X., Maiolino, R., ¨Ubler, H., et al. 2025, MNRAS, 544, 3900, doi: 10.1093/mnras/staf1867

    work page doi:10.1093/mnras/staf1867 2025

  44. [44]

    2026, ApJL, 996, L19, doi: 10.3847/2041-8213/ae247a Juodˇ zbalis, I., Ji, X., Maiolino, R., et al

    Jiang, F., Jia, Z., Zheng, H., et al. 2026, ApJL, 996, L19, doi: 10.3847/2041-8213/ae247a Juodˇ zbalis, I., Ji, X., Maiolino, R., et al. 2024a, MNRAS, 535, 853, doi: 10.1093/mnras/stae2367 Juodˇ zbalis, I., Maiolino, R., Baker, W. M., et al. 2024b, Nature, 636, 594, doi: 10.1038/s41586-024-08210-5 —. 2026, MNRAS, doi: 10.1093/mnras/stag086

    work page doi:10.3847/2041-8213/ae247a 2026

  45. [45]

    Kido, D., Ioka, K., Hotokezaka, K., Inayoshi, K., & Irwin, C. M. 2025, MNRAS, 544, 3407, doi: 10.1093/mnras/staf1898

    work page doi:10.1093/mnras/staf1898 2025

  46. [46]

    D., Onoue, M., Inayoshi, K., et al

    Kocevski, D. D., Onoue, M., Inayoshi, K., et al. 2023, ApJL, 954, L4, doi: 10.3847/2041-8213/ace5a0

    work page doi:10.3847/2041-8213/ace5a0 2023

  47. [47]

    D., Finkelstein, S

    Kocevski, D. D., Finkelstein, S. L., Barro, G., et al. 2025, ApJ, 986, 126, doi: 10.3847/1538-4357/adbc7d

    work page doi:10.3847/1538-4357/adbc7d 2025

  48. [48]

    2023, ApJL, 957, L7, doi: 10.3847/2041-8213/ad037a

    Kokorev, V., Fujimoto, S., Labbe, I., et al. 2023, ApJL, 957, L7, doi: 10.3847/2041-8213/ad037a

    work page doi:10.3847/2041-8213/ad037a 2023

  49. [49]

    I., Greene, J

    Kokorev, V., Caputi, K. I., Greene, J. E., et al. 2024a, ApJ, 968, 38, doi: 10.3847/1538-4357/ad4265

    work page doi:10.3847/1538-4357/ad4265

  50. [50]

    2024b, ApJ, 975, 178, doi: 10.3847/1538-4357/ad7d03

    Kokorev, V., Chisholm, J., Endsley, R., et al. 2024b, ApJ, 975, 178, doi: 10.3847/1538-4357/ad7d03

    work page doi:10.3847/1538-4357/ad7d03

  51. [51]

    Kormendy, J., & Ho, L. C. 2013, ARA&A, 51, 511, doi: 10.1146/annurev-astro-082708-101811 Kovaˇ cevi´ c, J., Popovi´ c, L.ˇC., & Dimitrijevi´ c, M. S. 2010, ApJS, 189, 15, doi: 10.1088/0067-0049/189/1/15 Labb´ e, I., van Dokkum, P., Nelson, E., et al. 2023, Nature, 616, 266, doi: 10.1038/s41586-023-05786-2

    work page internal anchor Pith review doi:10.1146/annurev-astro-082708-101811 2013

  52. [52]

    E., Matthee, J., et al

    Labbe, I., Greene, J. E., Matthee, J., et al. 2024, arXiv e-prints, arXiv:2412.04557, doi: 10.48550/arXiv.2412.04557

    work page doi:10.48550/arxiv.2412.04557 2024

  53. [53]

    E., Bezanson, R., et al

    Labbe, I., Greene, J. E., Bezanson, R., et al. 2025, ApJ, 978, 92, doi: 10.3847/1538-4357/ad3551

    work page doi:10.3847/1538-4357/ad3551 2025

  54. [54]

    2006, ApJ, 643, 112, doi: 10.1086/502798

    Laor, A. 2006, ApJ, 643, 112, doi: 10.1086/502798

    work page doi:10.1086/502798 2006

  55. [55]

    L., Finkelstein, S

    Larson, R. L., Finkelstein, S. L., Kocevski, D. D., et al. 2023, ApJL, 953, L29, doi: 10.3847/2041-8213/ace619

    work page doi:10.3847/2041-8213/ace619 2023

  56. [56]

    2025a, ApJ, 986, 101, doi: 10.3847/1538-4357/adbae2

    Li, J., Zhuang, M.-Y., Shen, Y., et al. 2025a, ApJ, 986, 101, doi: 10.3847/1538-4357/adbae2

    work page doi:10.3847/1538-4357/adbae2

  57. [57]

    I.-H., Shen, Y., Ho, L

    Li, J. I.-H., Shen, Y., Ho, L. C., et al. 2023, ApJ, 954, 173, doi: 10.3847/1538-4357/acddda 18Pang et al

    work page doi:10.3847/1538-4357/acddda 2023

  58. [58]

    2025b, arXiv e-prints, arXiv:2512.02093, doi: 10.48550/arXiv.2512.02093

    Li, Z.-J., Zou, S., Lyu, J., et al. 2025b, arXiv e-prints, arXiv:2512.02093, doi: 10.48550/arXiv.2512.02093

    work page doi:10.48550/arxiv.2512.02093

  59. [59]

    2024, ApJ, 974, 147, doi: 10.3847/1538-4357/ad6565

    Lin, X., Wang, F., Fan, X., et al. 2024, ApJ, 974, 147, doi: 10.3847/1538-4357/ad6565

    work page doi:10.3847/1538-4357/ad6565 2024

  60. [60]

    Lin et al., The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes, arXiv:2507.10659 (2025)

    Lin, X., Fan, X., Cai, Z., et al. 2025, arXiv e-prints, arXiv:2507.10659, doi: 10.48550/arXiv.2507.10659

    work page doi:10.48550/arxiv.2507.10659 2025

  61. [61]

    E., & Ma, Y

    Liu, H., Jiang, Y.-F., Quataert, E., Greene, J. E., & Ma, Y. 2025, ApJ, 994, 113, doi: 10.3847/1538-4357/ae0c19

    work page doi:10.3847/1538-4357/ae0c19 2025

  62. [62]

    2024, A&A, 691, A145, doi: 10.1051/0004-6361/202347640

    Maiolino, R., Scholtz, J., Curtis-Lake, E., et al. 2024, A&A, 691, A145, doi: 10.1051/0004-6361/202347640

    work page doi:10.1051/0004-6361/202347640 2024

  63. [63]

    2025, MNRAS, 538, 1921, doi: 10.1093/mnras/staf359

    Maiolino, R., Risaliti, G., Signorini, M., et al. 2025, MNRAS, 538, 1921, doi: 10.1093/mnras/staf359

    work page doi:10.1093/mnras/staf359 2025

  64. [64]

    V., de Graaff, A., Franx, M., et al

    Maseda, M. V., de Graaff, A., Franx, M., et al. 2024, A&A, 689, A73, doi: 10.1051/0004-6361/202449914

    work page doi:10.1051/0004-6361/202449914 2024

  65. [65]

    P., Brammer, G., et al

    Matthee, J., Naidu, R. P., Brammer, G., et al. 2024, ApJ, 963, 129, doi: 10.3847/1538-4357/ad2345

    work page doi:10.3847/1538-4357/ad2345 2024

  66. [66]

    2024, arXiv e-prints, arXiv:2412.04224, doi: 10.48550/arXiv.2412.04224

    Mazzolari, G., Gilli, R., Maiolino, R., et al. 2024, arXiv e-prints, arXiv:2412.04224, doi: 10.48550/arXiv.2412.04224

    work page doi:10.48550/arxiv.2412.04224 2024

  67. [67]

    A "Black Hole Star" Reveals the Remarkable Gas-Enshrouded Hearts of the Little Red Dots

    Naidu, R. P., Matthee, J., Katz, H., et al. 2025, arXiv e-prints, arXiv:2503.16596, doi: 10.48550/arXiv.2503.16596

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.2503.16596 2025

  68. [68]

    2024, ApJ, 961, 73, doi: 10.3847/1538-4357/ad0966

    Narayanan, D., Lower, S., Torrey, P., et al. 2024, ApJ, 961, 73, doi: 10.3847/1538-4357/ad0966

    work page doi:10.3847/1538-4357/ad0966 2024

  69. [69]

    2015, ARA&A, 53, 365, doi: 10.1146/annurev-astro-082214-122302

    Netzer, H. 2015, ARA&A, 53, 365, doi: 10.1146/annurev-astro-082214-122302

    work page internal anchor Pith review doi:10.1146/annurev-astro-082214-122302 2015

  70. [70]

    Osterbrock, D. E. 1977, ApJ, 215, 733, doi: 10.1086/155407

    work page doi:10.1086/155407 1977

  71. [71]

    S., Stalin, C

    Paliya, V. S., Stalin, C. S., Dom´ ınguez, A., & Saikia, D. J. 2024, MNRAS, 527, 7055, doi: 10.1093/mnras/stad3650

    work page doi:10.1093/mnras/stad3650 2024

  72. [72]

    2025, ApJ, 987, 48, doi: 10.3847/1538-4357/add7dd

    Pan, Z., Jiang, L., Guo, W.-J., et al. 2025, ApJ, 987, 48, doi: 10.3847/1538-4357/add7dd

    work page doi:10.3847/1538-4357/add7dd 2025

  73. [73]

    2022, Frontiers in Astronomy and Space Sciences, 9, 850409, doi: 10.3389/fspas.2022.850409 P´ erez-Gonz´ alez, P

    Panda, S. 2022, Frontiers in Astronomy and Space Sciences, 9, 850409, doi: 10.3389/fspas.2022.850409 P´ erez-Gonz´ alez, P. G., Barro, G., Rieke, G. H., et al. 2024, ApJ, 968, 4, doi: 10.3847/1538-4357/ad38bb

    work page doi:10.3389/fspas.2022.850409 2022

  74. [74]

    Peterson, B. M. 2011, in Narrow-Line Seyfert 1 Galaxies and their Place in the Universe, ed. L. Foschini, M. Colpi, L. Gallo, D. Grupe, S. Komossa, K. Leighly, & S. Mathur, 32, doi: 10.22323/1.126.0032

    work page doi:10.22323/1.126.0032 2011

  75. [75]

    2025, ApJ, 982, 10, doi: 10.3847/1538-4357/adb1dd

    Pucha, R., Juneau, S., Dey, A., et al. 2025, ApJ, 982, 10, doi: 10.3847/1538-4357/adb1dd

    work page doi:10.3847/1538-4357/adb1dd 2025

  76. [76]

    E., Greene, J

    Reines, A. E., Greene, J. E., & Geha, M. 2013, ApJ, 775, 116, doi: 10.1088/0004-637X/775/2/116

    work page internal anchor Pith review doi:10.1088/0004-637x/775/2/116 2013

  77. [77]

    E., & Volonteri, M

    Reines, A. E., & Volonteri, M. 2015, ApJ, 813, 82, doi: 10.1088/0004-637X/813/2/82

    work page internal anchor Pith review doi:10.1088/0004-637x/813/2/82 2015

  78. [78]

    T., Lacy, M., Storrie-Lombardi, L

    Richards, G. T., Lacy, M., Storrie-Lombardi, L. J., et al. 2006, ApJS, 166, 470, doi: 10.1086/506525

    work page internal anchor Pith review doi:10.1086/506525 2006

  79. [79]

    P., et al

    Rusakov, V., Watson, D., Nikopoulos, G. P., et al. 2025, arXiv e-prints, arXiv:2503.16595, doi: 10.48550/arXiv.2503.16595

    work page doi:10.48550/arxiv.2503.16595 2025

  80. [80]

    2025, arXiv e-prints, arXiv:2510.01034, doi: 10.48550/arXiv.2510.01034

    Scholtz, J., Carniani, S., Parlanti, E., et al. 2025, arXiv e-prints, arXiv:2510.01034, doi: 10.48550/arXiv.2510.01034

    work page doi:10.48550/arxiv.2510.01034 2025

Showing first 80 references.