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arxiv: 2606.27468 · v1 · pith:NIL5PT3Jnew · submitted 2026-06-25 · 🌌 astro-ph.GA

JWST Reveals Compact Nuclear Starbursts Masquerading as AGNs in Metal-Poor Dwarfs: Where Are the Accreting Intermediate-Mass Black Holes?

William Matzko (1) , Shobita Satyapal (1) , Jeffrey D. Mckaig (2 , 3) , Sara Doan (1) , Michael McDonald (4) , Archana Aravindan (5) , Gabriela Canalizo (4)
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Jenna M. Cann (2 6) Nicholas P. Abel (7) Omkar Bait (8 9) Laura Blecha (10) Torsten B\"oker (11) Thomas Bohn (12) Jacqueline Fischer (1) Stephanie LaMassa (13) Suzanne C. Madden (14) Mallory Molina (15) Barry Rothberg (1 16) D. Schaerer (17 18) Anil Seth (19) Remington O. Sexton (16). ((1) George Mason University (2) NASA Goddard Space Flight Center (3) Oak Ridge Associated Universities (4) University of California Riverside (5) The University of Texas at Austin (6) University of Maryland Baltimore County (7) University of Cincinnati (8) National Radio Astronomy Observatory (9) The NSF-Simons AI Institute for Cosmic Origins (10) University of Florida (11) European Space Agency c/o with STSCI (12) Hiroshima University (13) Space Telescope Science Institute (14) Universite Paris-Saclay (15) Vanderbilt University (16) U.S. Naval Observatory (17) Universite de Geneve (18) CNRS IRAP (19) University of Utah)
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Pith reviewed 2026-06-29 01:52 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords JWST spectroscopynuclear starburstsAGN diagnosticsmetal-poor dwarf galaxiesmid-infrared colorsphotoionization modelsintermediate-mass black holes
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The pith

Compact nuclear starbursts in metal-poor dwarf galaxies produce AGN-like mid-infrared colors without any accretion onto black holes.

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

Two low-mass, metal-poor galaxies were selected because their mid-infrared colors match those used to identify active galactic nuclei. JWST spectroscopy reveals compact nuclear starbursts instead, with no coronal lines, X-ray emission, or variability that would indicate accretion. The red colors arise from unresolved emission in the nuclear star cluster, and photoionization models show the lack of high-ionization lines cannot be attributed to low metallicity alone. The two systems differ in stellar populations and dust content yet both lack accretion signatures, indicating the absence of black hole activity is not merely a timing effect. These observations imply that standard AGN selection methods do not uniquely flag accreting black holes in such environments.

Core claim

The paper establishes that the extreme mid-infrared colors in these metal-poor dwarfs originate from compact, unresolved nuclear starburst emission rather than accretion, as confirmed by the absence of typical AGN tracers and by models demonstrating a genuine deficit of hard ionizing photons beyond what metallicity can explain.

What carries the argument

JWST/NIRSpec spectroscopy combined with photoionization models that isolate the contribution of nuclear star cluster emission to the mid-infrared colors.

If this is right

  • Widely used WISE color diagnostics can be contaminated by star formation in low-mass systems.
  • Metal-poor dwarf galaxies with nuclear starbursts do not show conditions for efficient black hole growth.
  • Such galaxies may lie below the mass or metallicity threshold where black hole seeds readily form or accrete.
  • Multiwavelength follow-up beyond mid-infrared colors is required to confirm AGN activity in dwarfs.

Where Pith is reading between the lines

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

  • Searches for intermediate-mass black holes in dwarfs may need to prioritize X-ray or variability data over infrared colors alone.
  • The findings connect to broader questions of whether low-metallicity environments suppress black hole seeding mechanisms.
  • Similar starburst contamination could affect AGN demographic studies at higher redshifts where dwarfs are more common.

Load-bearing premise

The lack of coronal lines, X-ray emission, and variability is taken to mean there is no accretion activity at all.

What would settle it

Detection of coronal lines or variable X-ray emission from the nuclei of similar metal-poor dwarfs selected by the same mid-infrared colors would show that accretion is present after all.

Figures

Figures reproduced from arXiv: 2606.27468 by (10) University of Florida, (11) European Space Agency, (12) Hiroshima University, (13) Space Telescope Science Institute, (14) Universite Paris-Saclay, (15) Vanderbilt University, 16), (16) U.S. Naval Observatory, (17) Universite de Geneve, 18), (18) CNRS, (19) University of Utah), (2) NASA Goddard Space Flight Center, 3), (3) Oak Ridge Associated Universities, (4) University of California, (5) The University of Texas at Austin, 6), (6) University of Maryland, (7) University of Cincinnati, (8) National Radio Astronomy Observatory, 9), (9) The NSF-Simons AI Institute for Cosmic Origins, Anil Seth (19), Archana Aravindan (5), Baltimore County, Barry Rothberg (1, c/o with STSCI, D. Schaerer (17, Gabriela Canalizo (4), IRAP, Jacqueline Fischer (1), Jeffrey D. Mckaig (2, Jenna M. Cann (2, Laura Blecha (10), Mallory Molina (15), Michael McDonald (4), Nicholas P. Abel (7), Omkar Bait (8, Remington O. Sexton (16). ((1) George Mason University, Riverside, Sara Doan (1), Shobita Satyapal (1), Stephanie LaMassa (13), Suzanne C. Madden (14), Thomas Bohn (12), Torsten B\"oker (11), William Matzko (1).

Figure 1
Figure 1. Figure 1: Left: A BPT ratio plot showing the narrow line ratios of J1601 and J1201 from SDSS indicated by the orange and red diamonds, respectively. We also display the narrow line ratios for the sample of BCDs showing [Ne V] emission from (Izotov et al. 2012, 2021; Hatano et al. 2024), which includes SBS 0335-032, another metal–poor dwarf with extreme MIR colors and MIR variability suggestive of accretion activity … view at source ↗
Figure 2
Figure 2. Figure 2: Stellar mass and metallicity of J1201 and J1601 in re￾lationship with previously identified dwarf AGN candidates and metal-poor systems. Optically selected dwarf AGNs from Reines et al. (2013) are shown for comparison, along with metal-poor [Ne V] emitters from Legrand et al. (2001); Izotov et al. (2012); Jaskot et al. (2019); Izotov et al. (2021); Hatano et al. (2024). Benchmark extremely metal-poor galax… view at source ↗
Figure 3
Figure 3. Figure 3: Paα emission map of J1601 from JWST/NIRSpec. A bright central (nuclear) source is observed, along with two knots of emission south of the nucleus and a faint extension toward the northwest. The dots indicate the centers of the spectral extraction apertures, each with a radius of 0. ′′5 (shown in the lower left). North is up and east is to the left. yses at the spaxel level. At the time the Cycle 1 data wer… view at source ↗
Figure 4
Figure 4. Figure 4: Spatial maps of J1601 showing representative emission from ionized gas, molecular gas, PAH emission, and the line-free 4.6 µm continuum. The panels show Brα, H2 1–0 O(3), PAH emission, and the 4.6 µm continuum. The contours in each panel trace the Paα emission shown in [PITH_FULL_IMAGE:figures/full_fig_p008_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Extracted JWST/NIRSpec spectra for the apertures shown in [PITH_FULL_IMAGE:figures/full_fig_p009_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Full nuclear JWST/NIRSpec spectrum with identified emission lines labeled. The spectrum is dominated by hydrogen recombination lines, molecular hydrogen transitions, and He,I emission. Unlabeled features were not considered robust line detections because they are not recovered consistently in the independent dither exposures. No infrared coronal lines or broad near-infrared emission-line components are obs… view at source ↗
Figure 7
Figure 7. Figure 7: Large-scale KCWI view of J1601 showing the region used for the matched-field maps (red box). This region covers ap￾proximately the same projected field as the JWST/NIRSpec IFU, al￾lowing direct comparison between the optical KCWI maps and the higher spatial resolution NIRSpec maps. The green box shows the nuclear extraction aperture used to search for optical coronal lines. The image displays the total int… view at source ↗
Figure 8
Figure 8. Figure 8: KCWI maps of J1601 extracted over a field of view comparable to the JWST/NIRSpec IFU. The panels show the [O III] λ5007 emission, the rest-frame 5100 Å continuum, the optical Wolf–Rayet feature, and the narrow He II λ4686/Hβ ratio. The [O III] emission is extended and clumpy, broadly following the large-scale ionized-gas morphology seen at higher spatial resolution in the JWST/NIRSpec recombination-line ma… view at source ↗
Figure 9
Figure 9. Figure 9: Nuclear KCWI spectrum of J1601 extracted from the nuclear aperture shown in [PITH_FULL_IMAGE:figures/full_fig_p015_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Spatially resolved BPT diagram for J1601 using KCWI spaxels with sufficient signal-to-noise. All measured spaxels fall in the star-forming region, with no spaxels occupying the composite or AGN region. 1.00 0.75 0.50 0.25 0.00 0.25 0.50 0.75 RA [arcsec] 1.5 1.0 0.5 0.0 0.5 1.0 D E C [ a r c s e c ] 7.6 7.8 8.0 8.2 8.4 1 2 +lo g ( O / H ) [PITH_FULL_IMAGE:figures/full_fig_p016_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Gas-phase metallicity map of J1601 derived from the Keck/KCWI IFU data using the direct method. Contours indicate the [O III] λ5007 flux. The metallicity distribution is approximately uniform across the field of view, with no significant radial gradient or localized nuclear enhancement. tinuum in the nuclear spectrum and the intrinsically weaker near-infrared He II transition compared to the optical He II… view at source ↗
Figure 12
Figure 12. Figure 12: Extinction and continuum maps of J1601. Top left: optical extinction, expressed as AV , derived from the Balmer decrement measured with KCWI. Top right: line-free rest-frame 5100 Å continuum from KCWI. Bottom left: near-infrared extinction, expressed as AV , derived from the Paα/Brα ratio measured with JWST/NIRSpec. Bottom right: line-free 4.6 µm continuum from JWST/NIRSpec. Contours in the extinction pan… view at source ↗
Figure 13
Figure 13. Figure 13: Near-infrared spectra of J1601 highlighting the CO bandhead absorption features in the nuclear region. The CO bandheads are detected in the nuclear extractions, indicating that red supergiants/late-type stars contribute to the continuum emission in the central regions of the galaxy. In contrast, these features are weak or absent in the off-nuclear regions. The presence of CO absorption in J1601, but not i… view at source ↗
Figure 14
Figure 14. Figure 14: Optical spectral region of J1601 showing the Wolf–Rayet features in the nuclear aperture. A faint broad He II component associated with WR stars is detected in the smaller nuclear extractions and becomes diluted in the larger aperture, indicating recent massive star formation concentrated toward the central region. The WR features are weak and are not accompanied by the coronal-line emission expected from… view at source ↗
Figure 15
Figure 15. Figure 15: Coronal-line luminosity as a function of WISE W2 luminosity for J1201 and J1601 compared to AGN samples from Lamperti et al. (2017) and Bohn et al. (2021). The solid lines show the best-fit relations for AGNs, with dashed lines indicating the intrinsic scatter. Downward arrows denote the observed 3σ upper limits for J1201 and J1601. In each plot, the value of the extinction at the wavelength of each line … view at source ↗
Figure 16
Figure 16. Figure 16: Upper limit on the optical [Ne V] λ3426 luminosity of J1601 compared with the quasar sample from Doan et al. (2025b) and metal-poor [Ne V] emitters from Izotov et al. (2021) and Hatano et al. (2024). The dashed line indicates the best-fit relation for the quasar sample. The color bar shows gas-phase metallicity in units of percent solar for the metal-poor comparison sample. J1601 lies significantly below … view at source ↗
Figure 17
Figure 17. Figure 17: JWST/NIRSpec nuclear spectrum of J1601 with WISE photometry overlaid. The red curve shows a CIGALE model including a heavily obscured AGN component using the SKIRTOR templates. The model reproduces the mid-infrared photometry, but requires substantial obscuration to remain consistent with the absence of near-infrared coronal lines. This fit should be interpreted as a test of whether a buried AGN could rep… view at source ↗
Figure 18
Figure 18. Figure 18: Predicted emission-line ratios for AGN photoionization models as a function of ionization parameter. The left panel shows models with log(m˙ ) = −3, and the right panel shows log(m˙ ) = −1. Curves correspond to different black hole masses. The predicted He II/Paα and [Si VI]/Paα ratios from the IMBH models are systematically higher than the observational upper limits, indicating that even weakly accreting… view at source ↗
Figure 19
Figure 19. Figure 19: Qualitative schematic comparing two possible states of compact nuclear starbursts in low-mass, metal-poor galaxies, based on the contrasting nuclear properties of J1201 and J1601. J1201 is shown as a more dust-enshrouded, chemically primitive nuclear starburst with high Paα equivalent width, redder mid-infrared colors, and no detected CO bandheads, Wolf–Rayet features, or PAH emission. J1601 is shown as a… view at source ↗
Figure 20
Figure 20. Figure 20: Predicted [Ne V] λ3426 luminosity as a function of oxy￾gen abundance for an AGN ionizing spectrum. The models assume a fixed bolometric luminosity, ionizing spectral shape, and pressure ratio in order to isolate the effect of metallicity. The [Ne V] lumi￾nosity does not decrease monotonically toward low metallicity, but instead increases over much of the metal-poor regime because of the declining dust-to-… view at source ↗
Figure 21
Figure 21. Figure 21: Comparison of the Gemini/GNIRS spectrum (red) with a matched extraction from JWST/NIRSpec (black). The JWST extraction aperture (right panel, red box) is chosen to approximate the 0.3 ′′ ×1.8 ′′ Gemini slit. Prominent emission lines are marked with dashed vertical lines. The Gemini spectrum has been convolved to the JWST spectral resolution. APPENDIX A. CORRECTION OF SINUSOIDAL MODULATIONS IN NIRSPEC IFU … view at source ↗
Figure 22
Figure 22. Figure 22: NEOWISE W1 (3.4 µm) and W2 (4.6 µm) light curves for J1601. The data span multiple epochs over several years. No significant variability is observed in either band beyond the measurement uncertainties. The absence of mid-infrared variability argues against the presence of a variable or transient AGN and supports the conclusion that the nuclear emission is not powered by accretion. The JWST extraction repr… view at source ↗
read the original abstract

We present JWST/NIRSpec spectroscopy of the low-mass, metal-poor galaxy SDSS~J160135.95+311353.7 (J1601), selected for its extreme mid-infrared colors and compact nuclear emission, placing it within widely used WISE color diagnostics for active galactic nuclei (AGNs). Despite this selection, we find no evidence for coronal lines, X-ray emission, or variability typically associated with accretion activity. We compare J1601 to SDSS~J120122.30+021108.3 (J1201), a similar but lower-mass, more metal-poor system studied previously (Doan, 2025). Both galaxies host compact nuclear starbursts but differ in their stellar populations and dust properties: J1601 shows CO bandhead absorption indicative of red supergiants, weak nuclear Wolf--Rayet features, and a circumnuclear PAH ring, consistent with a more developed recent starburst, while J1201 is more dust-enshrouded and chemically primitive. Despite these differences, neither system shows evidence for AGN activity, indicating that the absence of accretion is not simply due to evolutionary timing. Photoionization models show that the weakness of high-ionization emission cannot be explained by low metallicity alone, implying a genuine deficit of hard ionizing photons. Crucially, the red mid-infrared colors in both systems originate from compact, unresolved nuclear emission confined to the nuclear star cluster. These results demonstrate that compact nuclear starbursts can mimic AGN-like mid-infrared colors without accretion, and that commonly used AGN diagnostics may not uniquely identify accreting black holes in metal-poor dwarf galaxies. Our findings suggest that such systems may not provide the conditions required for efficient black hole growth and/or may lie near or below the regime where black hole seeds can form.

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 presents JWST/NIRSpec spectroscopy of the metal-poor dwarf galaxy SDSS J1601 (selected for extreme WISE mid-IR colors and compact nuclear emission) and compares it to the similar system J1201. Despite AGN-like mid-IR colors, no coronal lines ([Ne V], [Fe VII]), X-ray emission, or variability are detected. Stellar features (CO bandheads, weak WR lines, circumnuclear PAH) and photoionization models are used to attribute the emission to compact nuclear starbursts rather than accretion, concluding that standard AGN diagnostics may fail to identify (or rule out) accreting IMBHs in such galaxies.

Significance. If the central claim holds, the result is significant for AGN selection in low-mass, low-metallicity systems and for constraints on IMBH growth and seed formation. The work provides concrete observational examples of starburst mimicry of mid-IR colors, supported by multi-wavelength non-detections and direct comparison of two systems with differing starburst properties; this is a strength for an observational paper.

major comments (2)
  1. [Abstract and photoionization modeling section] Abstract and photoionization modeling section: The models are stated to show that 'the weakness of high-ionization emission cannot be explained by low metallicity alone,' but the text does not report composite starburst+AGN grids that test whether a weak, obscured AGN (L_bol ~10^40-10^42 erg s^-1, low Eddington ratio) remains consistent with the observed upper limits on coronal lines and X-rays while still producing the unresolved nuclear mid-IR colors.
  2. [Section discussing non-detections and AGN exclusion] Section discussing non-detections and AGN exclusion: The claim that absence of [Ne V], [Fe VII], X-rays, and variability rules out accretion is load-bearing for the conclusion that the mid-IR colors originate purely from the starburst. In metal-poor gas, coronal-line and X-ray suppression can occur even for accreting sources; without quantitative upper-limit modeling for IMBHs (including obscuration and Eddington-ratio dependence), the non-detections do not uniquely exclude a sub-dominant AGN component.
minor comments (2)
  1. [Abstract] The abstract and introduction could explicitly quote the numerical upper limits on X-ray luminosity and coronal-line equivalent widths to allow readers to assess the strength of the non-detections.
  2. [Figures and methods] Figure captions and text describing the circumnuclear PAH ring and CO absorption should clarify the spatial resolution and aperture sizes used to isolate nuclear versus extended emission.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments, which correctly identify areas where our analysis could be strengthened by additional discussion of possible weak AGN contributions. We respond point by point below.

read point-by-point responses

  1. Referee: [Abstract and photoionization modeling section] The models are stated to show that 'the weakness of high-ionization emission cannot be explained by low metallicity alone,' but the text does not report composite starburst+AGN grids that test whether a weak, obscured AGN (L_bol ~10^40-10^42 erg s^-1, low Eddington ratio) remains consistent with the observed upper limits on coronal lines and X-rays while still producing the unresolved nuclear mid-IR colors.

    Authors: We agree that our photoionization analysis used pure starburst grids and did not include composite starburst+AGN models to test the viability of a weak, obscured AGN component. The current models demonstrate that the observed line ratios, including the absence of high-ionization lines, are reproduced by starburst photoionization at the measured metallicities without requiring an additional hard radiation field. In the revised manuscript we will add a paragraph in the modeling section explicitly noting this limitation and discussing how a low-luminosity AGN might remain consistent with the data, while reiterating that the spatially unresolved mid-IR emission is co-located with the nuclear star cluster. revision: partial

  2. Referee: [Section discussing non-detections and AGN exclusion] The claim that absence of [Ne V], [Fe VII], X-rays, and variability rules out accretion is load-bearing for the conclusion that the mid-IR colors originate purely from the starburst. In metal-poor gas, coronal-line and X-ray suppression can occur even for accreting sources; without quantitative upper-limit modeling for IMBHs (including obscuration and Eddington-ratio dependence), the non-detections do not uniquely exclude a sub-dominant AGN component.

    Authors: The referee is correct that the non-detections alone do not furnish quantitative upper limits on a possible sub-dominant IMBH, particularly given known suppression effects in low-metallicity gas. The manuscript language states that we find 'no evidence' for accretion rather than claiming definitive exclusion. We will revise the relevant section to include an explicit caveat on this point, reference existing IMBH accretion models that incorporate obscuration and Eddington-ratio effects, and clarify that while the multi-wavelength data and starburst modeling favor a pure nuclear starburst origin for the mid-IR colors, a weak AGN component cannot be ruled out at high confidence without further quantitative analysis. revision: yes

Circularity Check

0 steps flagged

No circularity: purely observational analysis with external comparisons

full rationale

The manuscript is an observational JWST spectroscopy study reporting non-detections of AGN signatures and comparing two galaxies. No equations, fitted parameters, or derivations are present that reduce to inputs by construction. The reference to prior work on J1201 (Doan 2025) is an external comparison of independent observations, not a self-citation chain bearing the central claim. Photoionization models are invoked only to interpret line weakness, without any self-referential fitting or renaming of results. The analysis is self-contained against external benchmarks and contains no load-bearing steps matching the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard assumptions in emission-line diagnostics and photoionization modeling with no new free parameters or invented entities introduced.

axioms (1)
  • domain assumption Standard assumptions in photoionization modeling for interpreting high-ionization emission lines in low-metallicity gas
    Invoked to conclude that low metallicity alone cannot explain the observed line weakness.

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Works this paper leans on

100 extracted references · 11 canonical work pages · 6 internal anchors

  1. [1]

    T., Bogdán, Á., Kovács, O

    Ananna, T. T., Bogdán, Á., Kovács, O. E., Natarajan, P., & Hickox, R. C. 2024, ApJL, 969, L18

    2024

  2. [2]

    Arnaud, K. A. 1996, in Astronomical Society of the Pacific Conference Series, V ol. 101, Astronomical Data Analysis Software and Systems V , ed. G. H. Jacoby & J. Barnes, 17 Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., et al. 2013, A&A, 558, A33

    1996

  3. [3]

    C., & Dexter, J

    Begelman, M. C., & Dexter, J. 2026, ApJ, 996, 48

    2026

  4. [4]

    F., Satyapal, S., & Ellison, S

    Blecha, L., Snyder, G. F., Satyapal, S., & Ellison, S. L. 2018, MNRAS, 478, 3056 Bogdán, Á., Goulding, A. D., Natarajan, P., et al. 2024, Nature Astronomy, 8, 126

    2018

  5. [5]

    2021, ApJ, 911, 70 Böker, T., Arribas, S., Lützgendorf, N., et al

    Bohn, T., Canalizo, G., Veilleux, S., & Liu, W. 2021, ApJ, 911, 70 Böker, T., Arribas, S., Lützgendorf, N., et al. 2022, A&A, 661, A82

    2021

  6. [6]

    J., Liu, X., Chen, Y .-C., Shen, Y ., & Guo, H

    Burke, C. J., Liu, X., Chen, Y .-C., Shen, Y ., & Guo, H. 2021, MNRAS, 504, 543

    2021

  7. [7]

    2023, JWST Calibration Pipeline

    Bushouse, H., Eisenhamer, J., Dencheva, N., et al. 2023, JWST Calibration Pipeline

    2023

  8. [8]

    M., Satyapal, S., Abel, N

    Cann, J. M., Satyapal, S., Abel, N. P., et al. 2019, ApJL, 870, L2 —. 2018, ApJ, 861, 142

    2019

  9. [9]

    M., Satyapal, S., Bohn, T., et al

    Cann, J. M., Satyapal, S., Bohn, T., et al. 2020, ApJ, 895, 147 2 http://www.astropy.org

    2020

  10. [10]

    M., Satyapal, S., Rothberg, B., et al

    Cann, J. M., Satyapal, S., Rothberg, B., et al. 2021, ApJL, 912, L2

    2021

  11. [11]

    A., Endsley, R., et al

    Chisholm, J., Berg, D. A., Endsley, R., et al. 2024, arXiv e-prints, arXiv:2402.18643

    work page arXiv 2024

  12. [12]

    J., Olivier, G

    Cleri, N. J., Olivier, G. M., Backhaus, B. E., et al. 2025, ApJ, 994, 146

    2025

  13. [13]

    Collins, M. L. M., & Read, J. I. 2022, Nature Astronomy, 6, 647

    2022

  14. [14]

    J., Huang, Z.-P., Yin, Q

    Condon, J. J., Huang, Z.-P., Yin, Q. F., & Thuan, T. X. 1991, ApJ, 378, 65 de Graaff, A., Rix, H.-W., Naidu, R. P., et al. 2025, A&A, 701, A168

    1991

  15. [15]

    2007, ApJ, 660, 167

    Alonso-Herrero, A. 2007, ApJ, 660, 167

    2007

  16. [16]

    J., Stanway, E

    Eldridge, J. J., Stanway, E. R., Xiao, L., et al. 2017, PASA, 34, e058

    2017

  17. [17]

    L., & Massa, D

    Fitzpatrick, E. L., & Massa, D. 2009, ApJ, 699, 1209

    2009

  18. [18]

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

    Foreman-Mackey, D., Hogg, D. W., Lang, D., & Goodman, J. 2013, PASP, 125, 306

    2013

  19. [19]

    The quasi-star model for Little Red Dots: potential and challenges

    Gentile, F., Giavalisco, M., Daddi, E., et al. 2026, arXiv e-prints, arXiv:2606.06575

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  20. [20]

    D., Clayton, G

    Gordon, K. D., Clayton, G. C., Decleir, M., et al. 2023, ApJ, 950, 86 32

    2023

  21. [21]

    M., Lavaux, G., et al

    Graziani, R., Courtois, H. M., Lavaux, G., et al. 2019, MNRAS, 488, 5438

    2019

  22. [22]

    A., Heckman, T

    Groves, B. A., Heckman, T. M., & Kauffmann, G. 2006, MNRAS, 371, 1559

    2006

  23. [23]

    M., Ji, X., Chatzikos, M., Yan, R., & Ferland, G

    Gunasekera, C. M., Ji, X., Chatzikos, M., Yan, R., & Ferland, G. 2022, MNRAS, 512, 2310

    2022

  24. [24]

    M., van Hoof, P

    Gunasekera, C. M., van Hoof, P. A. M., Dehghanian, M., et al. 2025, RMxAA, 61, 120

    2025

  25. [25]

    2017, MNRAS, 468, 3935

    Habouzit, M., V olonteri, M., & Dubois, Y . 2017, MNRAS, 468, 3935

    2017

  26. [26]

    2023, ApJ, 959, 39

    Harikane, Y ., Zhang, Y ., Nakajima, K., et al. 2023, ApJ, 959, 39

    2023

  27. [27]

    2023, arXiv e-prints, arXiv:2304.03726

    Hatano, S., Ouchi, M., Nakajima, K., et al. 2023, arXiv e-prints, arXiv:2304.03726

    work page arXiv 2023

  28. [28]

    2024, ApJ, 966, 170

    Hatano, S., Ouchi, M., Umeda, H., et al. 2024, ApJ, 966, 170

    2024

  29. [29]

    Stellar winds of O-type stars traced by high ionization fine-structure emission lines with JWST/MIRI

    Hawcroft, C., Law, D. R., Smith, L. J., et al. 2026, arXiv e-prints, arXiv:2606.23456

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  30. [30]

    C., Micheva, G., Weilbacher, P

    Herenz, E. C., Micheva, G., Weilbacher, P. M., et al. 2023, Research Notes of the American Astronomical Society, 7, 99

    2023

  31. [31]

    F., Quataert, E., & Murray, N

    Hopkins, P. F., Quataert, E., & Murray, N. 2012, MNRAS, 421, 3522

    2012

  32. [32]

    G., & Storey, P

    Hummer, D. G., & Storey, P. J. 1987, MNRAS, 224, 801

    1987

  33. [33]

    K., Draine, B

    Hunt, L. K., Draine, B. T., Navarro, M. G., et al. 2025, ApJ, 993, 84

    2025

  34. [34]

    I., Stasi´nska, G., Meynet, G., Guseva, N

    Izotov, Y . I., Stasi´nska, G., Meynet, G., Guseva, N. G., & Thuan, T. X. 2006, A&A, 448, 955

    2006

  35. [35]

    I., & Thuan, T

    Izotov, Y . I., & Thuan, T. X. 2008, ApJ, 687, 133

    2008

  36. [36]

    I., Thuan, T

    Izotov, Y . I., Thuan, T. X., & Guseva, N. G. 2007, ApJ, 671, 1297 —. 2021, MNRAS, 508, 2556

    2007

  37. [37]

    I., Thuan, T

    Izotov, Y . I., Thuan, T. X., & Privon, G. 2012, MNRAS, 427, 1229

    2012

  38. [38]

    2022, A&A, 661, A80

    Jakobsen, P., Ferruit, P., Alves de Oliveira, C., et al. 2022, A&A, 661, A80

    2022

  39. [39]

    H., Cohen, M., Masci, F., et al

    Jarrett, T. H., Cohen, M., Masci, F., et al. 2011, ApJ, 735, 112

    2011

  40. [40]

    E., Dowd, T., Oey, M

    Jaskot, A. E., Dowd, T., Oey, M. S., Scarlata, C., & McKinney, J. 2019, ApJ, 885, 96

    2019

  41. [41]

    Jenkins, E. B. 2009, ApJ, 700, 1299

    2009

  42. [42]

    2025, arXiv e-prints, arXiv:2501.13082

    Ji, X., Maiolino, R., Übler, H., et al. 2025, arXiv e-prints, arXiv:2501.13082

    work page arXiv 2025

  43. [43]

    2026, MNRAS, 545, staf2235

    Ji, X., D’Eugenio, F., Juodžbalis, I., et al. 2026, MNRAS, 545, staf2235

    2026

  44. [44]

    E., & Yang, H

    Jiang, T., Malhotra, S., Rhoads, J. E., & Yang, H. 2019, ApJ, 872, 145

    2019

  45. [45]

    M., Tremonti, C., et al

    Kauffmann, G., Heckman, T. M., Tremonti, C., et al. 2003, MNRAS, 346, 1055

    2003

  46. [46]

    M., Guerrero, M

    Kehrig, C., Vílchez, J. M., Guerrero, M. A., et al. 2018, MNRAS, 480, 1081

    2018

  47. [47]

    2001, ApJ, 556, 121

    Trevena, J. 2001, ApJ, 556, 121

    2001

  48. [48]

    2025, ApJ, 993, 13

    Knutas, A., Adamo, A., Pedrini, A., et al. 2025, ApJ, 993, 13

    2025

  49. [49]

    2024, arXiv e-prints, arXiv:2407.04777

    Kokubo, M., & Harikane, Y . 2024, arXiv e-prints, arXiv:2407.04777

    work page arXiv 2024

  50. [50]

    A., & Smith, M

    Koudmani, S., Sijacki, D., Bourne, M. A., & Smith, M. C. 2019, MNRAS, 484, 2047

    2019

  51. [51]

    M., Graziani, R., et al

    Kourkchi, E., Courtois, H. M., Graziani, R., et al. 2020, AJ, 159, 67

    2020

  52. [52]

    2018, MNRAS, 480, 1247

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

    2018

  53. [53]

    A., Chandler, C

    Lacy, M., Baum, S. A., Chandler, C. J., et al. 2020, PASP, 132, 035001

    2020

  54. [54]

    2017, MNRAS, 467, 540

    Lamperti, I., Koss, M., Trakhtenbrot, B., et al. 2017, MNRAS, 467, 540

    2017

  55. [55]

    Laor, A., & Draine, B. T. 1993, ApJ, 402, 441

    1993

  56. [56]

    R., Hawcroft, C., Smith, L

    Law, D. R., Hawcroft, C., Smith, L. J., et al. 2024, ApJL, 976, L25

    2024

  57. [57]

    2001, ApJ, 560, 630

    Legrand, F., Tenorio-Tagle, G., Silich, S., Kunth, D., & Cerviño, M. 2001, ApJ, 560, 630

    2001

  58. [58]

    2005, in American Institute of Physics Conference

    Leitherer, C. 2005, in American Institute of Physics Conference

    2005

  59. [59]

    (LRDs)$^2$: The Low-ReDshift Little Red Dots Survey. II. DESI DR1 Sample

    Lin, X., Fan, X., Cai, Z., et al. 2026, arXiv e-prints, arXiv:2605.21574

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  60. [60]

    2025, MNRAS, 538, 1921

    Maiolino, R., Risaliti, G., Signorini, M., et al. 2025, MNRAS, 538, 1921

    2025

  61. [61]

    J., et al

    Mateos, S., Alonso-Herrero, A., Carrera, F. J., et al. 2013, MNRAS, 434, 941

    2013

  62. [62]

    P., Brammer, G., et al

    Matthee, J., Naidu, R. P., Brammer, G., et al. 2024, ApJ, 963, 129

    2024

  63. [63]

    2024, arXiv e-prints, arXiv:2412.04224

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

    work page arXiv 2024

  64. [64]

    D., Satyapal, S., Laor, A., et al

    McKaig, J. D., Satyapal, S., Laor, A., et al. 2024, ApJ, 976, 130

    2024

  65. [65]

    2019, Nature Astronomy, 3, 6

    Mezcua, M. 2019, Nature Astronomy, 3, 6

    2019

  66. [66]

    L., et al

    Mingozzi, M., Garcia del Valle-Espinosa, M., James, B. L., et al. 2025, ApJ, 985, 253

    2025

  67. [67]

    2021, ApJ, 922, 155

    Salehirad, S. 2021, ApJ, 922, 155

    2021

  68. [68]

    C., et al

    Morrissey, P., Matuszewski, M., Martin, D. C., et al. 2018, ApJ, 864, 93

    2018

  69. [69]

    J., Condon, J

    Murphy, E. J., Condon, J. J., Schinnerer, E., et al. 2011, ApJ, 737, 67

    2011

  70. [70]

    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

    work page internal anchor Pith review Pith/arXiv arXiv 2025

  71. [71]

    2025, A&A, 693, A50

    Napolitano, L., Castellano, M., Pentericci, L., et al. 2025, A&A, 693, A50

    2025

  72. [72]

    Groves, B. A. 2017, MNRAS, 466, 4403 33

    2017

  73. [73]

    2012, A&A, 539, A143

    Nieva, M.-F., & Przybilla, N. 2012, A&A, 539, A143

    2012

  74. [74]

    A new sample of Little Red Dots at $z<0.45$ in DESI DR1: Broad Balmer lines, low ionization spectrum and no variability

    Park, K., Torralba, A., Matthee, J., et al. 2026, arXiv e-prints, arXiv:2605.14233

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  75. [75]

    2025, MNRAS, 537, 956

    Partmann, C., Naab, T., Lahén, N., et al. 2025, MNRAS, 537, 956

    2025

  76. [76]

    2025, ApJ, 992, 96

    Pedrini, A., Adamo, A., Bik, A., et al. 2025, ApJ, 992, 96

    2025

  77. [77]

    2025, ApJ, 982, 10 Ramos Almeida, C., & Ricci, C

    Pucha, R., Juneau, S., Dey, A., et al. 2025, ApJ, 982, 10 Ramos Almeida, C., & Ricci, C. 2017, Nature Astronomy, 1, 679

    2025

  78. [78]

    O., et al

    Reefe, M., Satyapal, S., Sexton, R. O., et al. 2022, ApJ, 936, 140

    2022

  79. [79]

    E., Greene, J

    Reines, A. E., Greene, J. E., & Geha, M. 2013, ApJ, 775, 116 Rémy-Ruyer, A., Madden, S. C., Galliano, F., et al. 2014, A&A, 563, A31

    2013

  80. [80]

    Rupke, D. S. N. 2014, IFSRED: Data Reduction for Integral Field

    2014

Showing first 80 references.