pith. machine review for the scientific record. sign in

arxiv: 2604.25991 · v1 · submitted 2026-04-28 · 🌌 astro-ph.GA

Recognition: unknown

The GlimmIr: Spectroscopic Variability in a z~7 LRD Indicates Rapid Changes in Both the Narrow and Broad Line Regions

Erini Lambrides , Taylor A. Hutchison , Rebecca L. Larson , Pablo Arrabal Haro , Casey Papovich , Weida Hu , Nikko J. Cleri , Steven L. Finkelstein , Jonathan R. Trump , Pablo G. Perez-Gonzalez , Bingjie Wang , Dale D. Kocevski , John Chisholm , Amy Secunda , Sarah E. I. Bosman , Hollis Akins , Mitchell Karmen , Mark Dickinson , Volker Bromm , Bren E. Backhaus , Marco Chiaberge , Olivia R. Cooper , Yukta Ajay , Guillermo Barro , Danielle A. Berg , Jenna Cann , M. C. Cooper , Norman A. Grogin , Michaela Hirschmann , Marc Huertas-Company , Jeyhan S. Kartaltepe , Anton M. Koekemoer , Ray A. Lucas , Arianna S. Long , Roberto Gilli , Colin Norman , Andrew F. Ptak , Chris T. Richardson , Jane R. Rigby , Brittany N. Vanderhoof , L. Y. Aaron Yung , Jorge A. Zavala

Authors on Pith no claims yet

Pith reviewed 2026-05-07 15:24 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords Little Red Dotsspectroscopic variabilityhigh-redshift AGNJWST NIRSpecbroad line regionnarrow line regionblack hole accretionearly universe galaxies
0
0 comments X

The pith

A z~7 Little Red Dot shows 30% flux changes in continuum, broad lines, and [OIII] over 13 rest-frame days.

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

The paper establishes the first detection of spectroscopic variability in a Little Red Dot at redshift approximately 7 by comparing JWST/NIRSpec spectra separated by 99 observer-frame days. The observations reveal roughly 30% differences in the continuum and broad-line fluxes along with a 42% difference in the narrow [OIII]5008 line, and the authors rule out slit placement or simple calibration offsets through multiple cross-checks with additional epochs. This variability indicates that the central source can directly illuminate gas on scales larger than the broad-line region. It further suggests that narrow-line emission arises from gas ionized by the LRD itself rather than host-galaxy star formation. These findings require revisions to models of black-hole properties and obscuration in these early systems.

Core claim

We show for the first time spectroscopic variability in a z ~ 7 LRD. Comparing spectra taken 99 days apart (~13 rest-days), we find a ~30% difference in the continuum and broad-line flux, and a 42% difference in [OIII]5008 flux. Assuming LRDs are a type of accreting black hole system, this implies direct sight-lines must exist from the accretion disk to the surrounding nebular gas on scales beyond the broad-line region, and thus any high-density gas interpretations must allow for covering fractions < 100%. The [OIII] line emission is likely not galaxy process-dominated, with a significant population of the narrow-line emitting gas closest to the broad-line region being directly ionized by Lr

What carries the argument

Multi-epoch comparison of JWST/NIRSpec F290LP/G395M spectra revealing intrinsic flux variations in continuum, broad emission lines, and narrow [OIII]5008.

Load-bearing premise

The measured flux differences between epochs are intrinsic astrophysical variability rather than residual instrumental or calibration effects.

What would settle it

An independent re-reduction or new observation of the same source using identical instrument settings that recovers identical flux levels in all components would falsify the claim of rapid intrinsic changes.

Figures

Figures reproduced from arXiv: 2604.25991 by Amy Secunda, Andrew F. Ptak, Anton M. Koekemoer, Arianna S. Long, Bingjie Wang, Bren E. Backhaus, Brittany N. Vanderhoof, Casey Papovich, Chris T. Richardson, Colin Norman, Dale D. Kocevski, Danielle A. Berg, Erini Lambrides, Guillermo Barro, Hollis Akins, Jane R. Rigby, Jenna Cann, Jeyhan S. Kartaltepe, John Chisholm, Jonathan R. Trump, Jorge A. Zavala, L. Y. Aaron Yung, Marc Huertas-Company, Marco Chiaberge, Mark Dickinson, M. C. Cooper, Michaela Hirschmann, Mitchell Karmen, Nikko J. Cleri, Norman A. Grogin, Olivia R. Cooper, Pablo Arrabal Haro, Pablo G. Perez-Gonzalez, Ray A. Lucas, Rebecca L. Larson, Roberto Gilli, Sarah E. I. Bosman, Steven L. Finkelstein, Taylor A. Hutchison, Volker Bromm, Weida Hu, Yukta Ajay.

Figure 1
Figure 1. Figure 1: Spectroscopic Variability in an Early Little Red Dot. view at source ↗
Figure 2
Figure 2. Figure 2: Spectroscopic Variability in an Early Little Red Dot. view at source ↗
Figure 3
Figure 3. Figure 3: (left)Synthetic F444W for all NIRSpec Observations: Circles correspond to NIRCam imaging, diamonds correspond to prism observations, squares correspond to G395M observations. Colors of non-NIRCam points correspond to the slit orien￾tations shown in the right-most panel. (right) Slit Orientations for all multi-epoch observations of the GlimmIR (see view at source ↗
Figure 4
Figure 4. Figure 4: Comparing to other Dually Observed Sources view at source ↗
Figure 5
Figure 5. Figure 5: The existence of direct sight-lines from the accre￾tion indicates a covering fraction < 1 of the broad-line gas. the Balmer self-absorption. The same level of flux dif￾ferences found for Hα, our most constrained broad line feature, is within the error of the continuum variability increase. We then test if the flux difference is truly intrinsic or due to unaccounted for systematic differences between the tw… view at source ↗
Figure 6
Figure 6. Figure 6: Pathloss Impact: The differences in flux between the three spectral regions shown are greater than the differences in flux due to including or not including a pathloss correction. As described in Section 2 and shown in view at source ↗
Figure 7
Figure 7. Figure 7: (a) F115 (blue slitlets are THRILS and red slitlets are C3PO) (b) F444W overlapped – note the center of the F444W emission is offset from the center of the F115W blob. (c) The two sub-aperture definitions for THRILS, and (d) the two sub-aperture definitions for C3PO. There are some known resolved blue features – especially seen in the F115W imaging, with one “blob” in particular extending within the F444W … view at source ↗
Figure 8
Figure 8. Figure 8: Spectra labels are defined in Section 7. C3PO(4) is slightly greater than C3PO(3) – due to the brightness of Hα, we are potentially seeing the impact of sub-sampling on (4) or off (3) center of the AGN. driven by varying coverage of the UV-blue components due to the different MSA configurations between programs. We split the extraction aperture in half (spatially) for both C3PO and THRILS observations, and… view at source ↗
read the original abstract

The enigmatic population of ``Little Red Dots'' (LRDs) sit at the center of some of the largest debates in extragalactic astronomy today. The source(s) of ionizing emission and the physical scale over which it governs is still largely unknown. We show for the first time spectroscopic variability in a z ~ 7 LRD. Comparing a recently obtained 10.2 hr JWST/NIRSpec F290LP/G395M spectrum via the C3PO survey to an 8.4 hr F290LP/G395M spectrum taken 99 days earlier (~13 rest-days) via the THRILS survey, we find a ~30% $ difference in the continuum and broad-line flux, and a 42% difference between [OIII]5008 flux in the two epochs. Through rigorous testing, we confirm that such differences are not the result of differing MSA slit placements on source nor merely flux calibration offsets. These results are further corroborated by both a similar continuum and [OIII]5008 flux differences found in NIRSpec prism/clear observations of the source at an epoch taken approximately a year earlier than the THRILS observations via RUBIES and an additional observation fortuitously taken during the THRILS epoch (within a rest-day) via the CAPERS survey. Assuming LRDs are a type of accreting black hole system, this implies direct sight-lines must exist from the accretion disk to the surrounding nebular gas on scales beyond the broad-line region, and thus any high-density gas interpretations must allow for covering fractions < 100%. Furthermore, these results show the [OIII] line emission is likely not galaxy process-dominated, with a significant population of the narrow-line emitting gas closest to the broad-line region being directly ionized by the LRD. Finally, these results highlight the need for new approaches in inferring black hole properties of these systems, accounting for the lack of significant ionization via star formation, and/or exploring more exotic host-galaxy conditions at these early epochs.

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 paper reports the first detection of spectroscopic variability in a z~7 Little Red Dot (LRD) using JWST/NIRSpec observations. Comparing two G395M spectra from the THRILS and C3PO surveys separated by 99 observer-frame days (~13 rest-frame days), the authors measure ~30% differences in continuum and broad-line fluxes and a 42% difference in [OIII]5008 flux. These changes are corroborated by prism observations from RUBIES (taken ~1 year earlier) and CAPERS (taken within ~1 rest-day of THRILS). Rigorous tests are claimed to rule out instrumental artifacts from MSA slit placement and flux calibration. The authors interpret this as evidence for direct sight-lines from an accretion disk to nebular gas beyond the broad-line region (assuming LRDs are accreting black holes), implying covering fractions <100% and that [OIII] emission is not purely galaxy-process dominated.

Significance. If the variability is confirmed to be astrophysical rather than residual systematics, this would represent a significant advance as the first spectroscopic variability detection in an LRD at z~7. It would provide direct constraints on the physical scale and geometry of the ionizing source and narrow-line gas, supporting AGN-like models with partial covering and highlighting limitations in current black-hole mass and accretion-rate inferences for these objects. The multi-epoch, multi-instrument cross-checks add strength if quantitative metrics are provided.

major comments (2)
  1. [Abstract and results section] Abstract and results section: The central claim of intrinsic variability rests on the assertion that 'rigorous testing' rules out MSA slit-placement and flux-calibration effects, yet no quantitative metrics are provided (e.g., modeled slit-loss fractions for the point-source component, continuum overlap residuals between epochs, cross-program flux-calibration precision, or statistical significance/error bars on the 30% and 42% differences). A 30-42% offset is comparable in magnitude to plausible residual systematics in faint high-z NIRSpec data, so these details are load-bearing for distinguishing astrophysical changes from artifacts.
  2. [Results and discussion] The corroborating prism observations (RUBIES and CAPERS) are presented as independent confirmation, but the manuscript does not quantify the consistency of the flux scales across grating vs. prism modes or address potential differences in absolute calibration between programs.
minor comments (2)
  1. [Abstract] The abstract would benefit from a brief statement of the measured flux ratios with uncertainties and the exact time baselines in both observer and rest frames.
  2. [Abstract] Notation for the flux differences (e.g., the ~30% difference symbol) should be clarified for precision.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their detailed and constructive review. The comments correctly identify areas where additional quantitative detail would strengthen the presentation of the variability results. We address each major comment below and have revised the manuscript accordingly to include the requested metrics and comparisons.

read point-by-point responses
  1. Referee: [Abstract and results section] Abstract and results section: The central claim of intrinsic variability rests on the assertion that 'rigorous testing' rules out MSA slit-placement and flux-calibration effects, yet no quantitative metrics are provided (e.g., modeled slit-loss fractions for the point-source component, continuum overlap residuals between epochs, cross-program flux-calibration precision, or statistical significance/error bars on the 30% and 42% differences). A 30-42% offset is comparable in magnitude to plausible residual systematics in faint high-z NIRSpec data, so these details are load-bearing for distinguishing astrophysical changes from artifacts.

    Authors: We agree that the current manuscript would benefit from explicit quantitative metrics to support the claim that the observed differences are astrophysical. The revised version adds a dedicated subsection in the results that reports: (i) modeled slit-loss fractions for the point-source component using the known MSA shutter geometry and source position, (ii) measured continuum overlap residuals between the two G395M epochs after re-extraction with identical apertures, (iii) cross-program flux-calibration precision estimated from standard-star observations and overlapping sources in the same programs (typically 8-15% at these wavelengths), and (iv) statistical significance of the 30% continuum/broad-line and 42% [OIII] differences with propagated uncertainties. These additions show that the variations exceed the estimated systematic floor. revision: yes

  2. Referee: [Results and discussion] The corroborating prism observations (RUBIES and CAPERS) are presented as independent confirmation, but the manuscript does not quantify the consistency of the flux scales across grating vs. prism modes or address potential differences in absolute calibration between programs.

    Authors: We acknowledge the need for explicit cross-mode and cross-program calibration comparisons. The revised manuscript now includes a quantitative assessment of the grating-to-prism flux-scale consistency for this source, demonstrating that the continuum and [OIII] trends align within the combined calibration uncertainties. We also report the absolute calibration offsets between the RUBIES, CAPERS, THRILS, and C3PO programs, derived from standard stars and common sources observed across programs, which fall within the 10-20% range typical for NIRSpec at 3-5 microns. These values are now stated explicitly in the text and a new supplementary table. revision: yes

Circularity Check

0 steps flagged

No circularity: pure observational comparison of independent multi-epoch spectra

full rationale

The paper's central claim is an empirical detection of flux differences (~30% continuum/broad-line, 42% [OIII]) between NIRSpec G395M and prism observations from four separate programs (THRILS, C3PO, RUBIES, CAPERS) separated by ~13–99 rest-days. These differences are presented as direct measurements after the authors describe tests ruling out slit-placement and calibration artifacts; no equations, fitted parameters, model derivations, or ansatzes are invoked to produce the variability result. The BH-system interpretation is explicitly conditional ('Assuming LRDs are...') and does not enter any derivation chain. No self-citations, uniqueness theorems, or renamings of known results are used as load-bearing steps. The result is therefore self-contained against external benchmarks (the raw spectra themselves) and receives a score of 0.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the interpretation that flux differences are astrophysical and on the assumption that LRDs are accreting black holes; no free parameters or invented entities are introduced.

axioms (1)
  • domain assumption JWST/NIRSpec flux calibration and slit placement effects can be rigorously tested and ruled out as causes of observed differences across epochs
    The paper relies on this to attribute changes to intrinsic variability.

pith-pipeline@v0.9.0 · 5905 in / 1343 out tokens · 99079 ms · 2026-05-07T15:24:30.691119+00:00 · methodology

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

56 extracted references · 56 canonical work pages · 2 internal anchors

  1. [1]

    arXiv e-prints , keywords =

    Akins, H. B., Casey, C. M., Lambrides, E., et al. 2024, arXiv e-prints, arXiv:2406.10341, doi: 10.48550/arXiv.2406.10341 Arrabal Haro, P., Dickinson, M., Finkelstein, S. L., et al. 2023, ApJL, 951, L22, doi: 10.3847/2041-8213/acdd54 Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., et al. 2013, AAP, 558, A33, doi: 10.1051/0004-6361/201322068

  2. [2]

    , keywords =

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

  3. [3]

    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

  4. [5]

    D., Drew, J

    Baskin, A., & Laor, A. 2005b, MNRAS, 358, 1043, doi: 10.1111/j.1365-2966.2005.08841.x

  5. [6]

    D., & McKee, C

    Blandford, R. D., & McKee, C. F. 1982, ApJ, 255, 419, doi: 10.1086/159843

  6. [7]

    J., Stone, Z., Shen, Y ., & Jiang, Y .-F

    Burke, C. J., Stone, Z., Shen, Y., & Jiang, Y.-F. 2025, arXiv e-prints, arXiv:2511.16082, doi: 10.48550/arXiv.2511.16082

  7. [8]

    2022, JWST Calibration Pipeline, 1.8.5 Zenodo, doi: 10.5281/zenodo.7429939

    Bushouse, H., Eisenhamer, J., Dencheva, N., et al. 2022, JWST Calibration Pipeline, 1.8.5 Zenodo, doi: 10.5281/zenodo.7429939

  8. [9]

    2025, JWST Calibration Pipeline, 1.20.2 Zenodo, doi: 10.5281/zenodo.17515973

    Bushouse, H., Eisenhamer, J., Dencheva, N., et al. 2025, JWST Calibration Pipeline, 1.20.2 Zenodo, doi: 10.5281/zenodo.17515973

  9. [10]

    J., Treu, T., et al

    Dalmasso, N., Watson, P. J., Treu, T., et al. 2025, MNRAS, 544, 1915, doi: 10.1093/mnras/staf1837 11 de Graaff, A., Brammer, G., Weibel, A., et al. 2025a, AAP, 697, A189, doi: 10.1051/0004-6361/202452186 de Graaff, A., Hviding, R. E., Naidu, R. P., et al. 2025b, arXiv e-prints, arXiv:2511.21820, doi: 10.48550/arXiv.2511.21820 D’Eugenio, F., Nelson, E., Ji...

  10. [11]

    2022, A&A, 661, A81, doi: 10.1051/0004-6361/202142673

    Ferruit, P., Jakobsen, P., Giardino, G., et al. 2022, AAP, 661, A81, doi: 10.1051/0004-6361/202142673

  11. [12]

    , keywords =

    Finkelstein, S. L., Leung, G. C. K., Bagley, M. B., et al. 2024, ApJL, 969, L2, doi: 10.3847/2041-8213/ad4495

  12. [13]

    W., Lang, D., & Goodman, J

    Foreman-Mackey, D., Hogg, D. W., Lang, D., & Goodman, J. 2013, PASP, 125, 306, doi: 10.1086/670067

  13. [14]

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

    Furtak, L. J., Labb´ e, I., Zitrin, A., et al. 2023, arXiv e-prints, arXiv:2308.05735, doi: 10.48550/arXiv.2308.05735

  14. [15]

    Investigating photometric and spectroscopic variability in the multiply imaged little red dot A2744-QSO1

    Furtak, L. J., Secunda, A. R., Greene, J. E., et al. 2025, A&A, 698, A227, doi: 10.1051/0004-6361/202554110

  15. [16]

    Gaskell, C. M. 2009, NAR, 53, 140, doi: 10.1016/j.newar.2009.09.006 Gravity Collaboration, Sturm, E., Dexter, J., et al. 2018, Nature, 563, 657, doi: 10.1038/s41586-018-0731-9

  16. [17]

    Greene, I

    Greene, J. E., Labbe, I., Goulding, A. D., et al. 2023, arXiv e-prints, arXiv:2309.05714, doi: 10.48550/arXiv.2309.05714

  17. [18]

    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

  18. [19]

    , keywords =

    Horne, K. 1986, PASP, 98, 609, doi: 10.1086/131801

  19. [20]

    A., Larson, R

    Hutchison, T. A., Larson, R. L., Arrabal Haro, P., et al. 2025, arXiv e-prints, arXiv:2512.12509. https://arxiv.org/abs/2512.12509 Ili´ c, D., Popovi´ c, L.ˇC., Shapovalova, A. I., et al. 2015, Journal of Astrophysics and Astronomy, 36, 433, doi: 10.1007/s12036-015-9360-y

  20. [21]

    , keywords =

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

  21. [22]

    2020, ARA&A, 58, 27, doi: 10.1146/annurev-astro-120419-014455

    Inayoshi, K., Visbal, E., & Haiman, Z. 2020, Annual Review of Astronomy and Astrophysics, 58, 27, doi: 10.1146/annurev-astro-120419-014455

  22. [23]

    2025, arXiv e-prints, arXiv:2501.13082, doi: 10.48550/arXiv.2501.13082

    Ji, X., Maiolino, R., ¨Ubler, H., et al. 2025, arXiv e-prints, arXiv:2501.13082, doi: 10.48550/arXiv.2501.13082

  23. [24]

    Deciphering the JWST spectrum of a ‘little red dot’ at <i>z</i> ∼ 4.53: An obscured AGN and its star-forming host

    Killi, M., Watson, D., Brammer, G., et al. 2024, AAP, 691, A52, doi: 10.1051/0004-6361/202348857

  24. [25]

    Hidden Little Monsters: Spectroscopic Iden- tification of Low-Mass, Broad-Line AGN atz >5 with CEERS

    Kocevski, D. D., Onoue, M., Inayoshi, K., et al. 2023, arXiv e-prints, arXiv:2302.00012, doi: 10.48550/arXiv.2302.00012

  25. [26]

    , keywords =

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

  26. [27]

    Kokorev, S

    Kokorev, V., Fujimoto, S., Labbe, I., et al. 2023, arXiv e-prints, arXiv:2308.11610, doi: 10.48550/arXiv.2308.11610

  27. [28]

    I., Greene, J

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

  28. [29]

    , keywords =

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

  29. [30]

    The case for super-Eddington accretion in JWST broad-line AGN during the first billion years

    Lambrides, E., Garofali, K., Larson, R., et al. 2024, arXiv e-prints, arXiv:2409.13047, doi: 10.48550/arXiv.2409.13047

  30. [31]

    arXiv e-prints , keywords =

    Lambrides, E., Larson, R., Hutchison, T., et al. 2025, arXiv e-prints, arXiv:2509.09607, doi: 10.48550/arXiv.2509.09607

  31. [32]

    J., Steenbrugge, K

    Landt, H., Ward, M. J., Steenbrugge, K. C., & Ferland, G. J. 2015, MNRAS, 449, 3795, doi: 10.1093/mnras/stv062

  32. [33]

    Larson, S.L

    Larson, R. L., Finkelstein, S. L., Kocevski, D. D., et al. 2023, arXiv e-prints, arXiv:2303.08918, doi: 10.48550/arXiv.2303.08918

  33. [34]

    2026, arXiv e-prints, arXiv:2603.01473

    Lin, R., Zheng, Z.-Y., Wang, J., et al. 2026, arXiv e-prints, arXiv:2603.01473. https://arxiv.org/abs/2603.01473

  34. [35]

    L., Ivezi´ c,ˇZ., Sesar, B., et al

    MacLeod, C. L., Ivezi´ c,ˇZ., Sesar, B., et al. 2012, ApJ, 753, 106, doi: 10.1088/0004-637X/753/2/106

  35. [36]

    Matthee et al.,Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z∼ 5 Revealed by the EIGER and FRESCO JWST Surveys,Astrophys

    Matthee, J., Naidu, R. P., Brammer, G., et al. 2023, arXiv e-prints, arXiv:2306.05448, doi: 10.48550/arXiv.2306.05448

  36. [37]

    P., Matthee, J., Katz, H., et al

    Naidu, R. P., Matthee, J., Katz, H., et al. 2025, arXiv e-prints, arXiv:2503.16596, doi: 10.48550/arXiv.2503.16596 P´ erez-Gonz´ alez, P. G., Barro, G., Rieke, G. H., et al. 2024, ApJ, 968, 4, doi: 10.3847/1538-4357/ad38bb P´ erez-Gonz´ alez, P. G., Barro, G., Carniani, S., et al. 2026, arXiv e-prints, arXiv:2602.20247, doi: 10.48550/arXiv.2602.20247

  37. [38]

    Peterson, B. M. 1993, PASP, 105, 247, doi: 10.1086/133140

  38. [39]

    M., Denney, K

    Peterson, B. M., Denney, K. D., De Rosa, G., et al. 2013, ApJ, 779, 109, doi: 10.1088/0004-637X/779/2/109

  39. [40]

    The Astronomical Journal , author =

    Price-Whelan, A. M., Sip˝ ocz, B. M., G¨ unther, H. M., et al. 2018, AJ, 156, 123, doi: 10.3847/1538-3881/aabc4f

  40. [41]

    E., Eckart, A., Valencia-S., M., et al

    Rashed, Y. E., Eckart, A., Valencia-S., M., et al. 2015, MNRAS, 454, 2918, doi: 10.1093/mnras/stv2066

  41. [42]

    Rauscher, B. J. 2024, PASP, 136, 015001, doi: 10.1088/1538-3873/ad1b36

  42. [43]

    2025, arXiv e-prints, arXiv:2508.20177

    Ronayne, K., Papovich, C., Kirkpatrick, A., et al. 2025, arXiv e-prints, arXiv:2508.20177, doi: 10.48550/arXiv.2508.20177

  43. [44]

    S., Jiang, Y.-F., et al

    Secunda, A., Somerville, R. S., Jiang, Y.-F., et al. 2026, ApJ, 996, 6, doi: 10.3847/1538-4357/ae1f08 12

  44. [45]

    2021, MNRAS, 500, 2871, doi: 10.1093/mnras/staa3278

    Gorjian, V. 2021, MNRAS, 500, 2871, doi: 10.1093/mnras/staa3278

  45. [46]

    The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results

    Shen, Y., Grier, C. J., Horne, K., et al. 2024, ApJS, 272, 26, doi: 10.3847/1538-4365/ad3936

  46. [47]

    2019, Contemporary Physics, 60, 111, doi: 10.1080/00107514.2019.1615715

    Smith, A., & Bromm, V. 2019, Contemporary Physics, 60, 111, doi: 10.1080/00107514.2019.1615715

  47. [48]

    B., Fries, L

    Smith, T. B., Fries, L. B., Trump, J. R., et al. 2025, ApJ, 995, 185, doi: 10.3847/1538-4357/ae1f18 Smithsonian Astrophysical Observatory. 2000, SAOImage DS9: A utility for displaying astronomical images in the X11 window environment,, Astrophysics Source Code Library, record ascl:0003.002 http://ascl.net/0003.002

  48. [49]

    P., Plat, A., et al

    Tang, M., Stark, D. P., Plat, A., et al. 2025, arXiv e-prints, arXiv:2505.06359, doi: 10.48550/arXiv.2505.06359

  49. [50]

    J., Finkelstein, S

    Taylor, A. J., Finkelstein, S. L., Kocevski, D. D., et al. 2025a, ApJ, 986, 165, doi: 10.3847/1538-4357/add15b

  50. [51]

    J., Kokorev, V., Kocevski, D

    Taylor, A. J., Kokorev, V., Kocevski, D. D., et al. 2025b, ApJL, 989, L7, doi: 10.3847/2041-8213/ade789 Vanden Berk, D. E., Wilhite, B. C., Kron, R. G., et al. 2004, ApJ, 601, 692, doi: 10.1086/380563

  51. [52]
  52. [53]

    , keywords =

    Wang, B., de Graaff, A., Davies, R. L., et al. 2025a, ApJ, 984, 121, doi: 10.3847/1538-4357/adc1ca

  53. [54]

    The Missing Hard Photons of Little Red Dots: Their Incident Ionizing Spectra Resemble Massive Stars

    Wang, B., Leja, J., Katz, H., et al. 2025b, arXiv e-prints, arXiv:2508.18358, doi: 10.48550/arXiv.2508.18358

  54. [56]

    Little red dot variability over a century reveals black hole envelope via a giant Einstein cross

    Zhang, Z., Li, M., Oguri, M., et al. 2025b, arXiv e-prints, arXiv:2512.05180, doi: 10.48550/arXiv.2512.05180

  55. [57]

    Zhou, S., Sun, M., Zhang, Z., Chen, J., & Ho, L. C. 2025, ApJ, 991, 137, doi: 10.3847/1538-4357/adfd5f

  56. [58]

    J., & Sutherland, R

    Zhu, P., Kewley, L. J., & Sutherland, R. S. 2023, ApJ, 954, 175, doi: 10.3847/1538-4357/acd757 All Authors and Affiliations Erini Lambrides ,1, 2, 3 Taylor A. Hutchison ,1, 4, 3,∗ Rebecca L. Larson ,5,† Pablo Arrabal Haro ,6, 1 Casey Papovich ,7, 8 Weida Hu ,7, 8 Nikko J. Cleri ,9, 10, 11 Steven L. Finkelstein ,12, 13 Jonathan R. Trump ,14 Pablo G. P´erez...