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REVIEW 3 major objections 3 minor 2 cited by

Balmer absorption in 14 FeLoBAL quasars, eight new detections, is strongest at the lowest outflow speeds and luminosities.

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

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2026-08-04 21:55 UTC pith:RC6GWQS3

load-bearing objection A solid, careful detection paper whose population-level correlations rest on a covering model that the authors themselves show is too simple for at least one object. the 3 major comments →

arxiv 2509.07611 v1 pith:RC6GWQS3 submitted 2025-09-09 astro-ph.GA

Balmer Absorption in Iron Low-Ionization Broad Absorption Line Quasars

Karen M. Leighly , Sarah C. Gallagher , Hyunseop Choi , Donald M. Terndrup , Julianna R. Voelker , Gordon T. Richards , Leah K. Morabito This is my paper
classification astro-ph.GA
keywords broad absorption line quasarsFeLoBAL quasarsBalmer absorptionloitering outflow FeLoBAL quasarspartial coveringEddington ratioLittle Red Dotsquasar outflows
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

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

This paper reports that Balmer absorption lines—rare because they require dense, high-column gas—are present in 14 iron low-ionization broad absorption line quasars, eight previously unknown. The authors show that nearly all of these objects belong to the 'loitering outflow' class: compact, slow outflows near the black hole with low accretion rates. The key population result is that dN/dv, the column of absorbing hydrogen per unit outflow speed, is anticorrelated with luminosity and Eddington ratio: the deepest and narrowest absorption appears in the faintest, least luminous objects. They also find the absorption width correlates with α_oi, a spectral slope tied to Eddington ratio. If right, the paper turns Balmer absorption from a curiosity into a diagnostic of a specific, low-accretion outflow phase, and it suggests a link to the Balmer-absorbing Little Red Dots.

Core claim

On the paper's terms, the discovery is that Balmer absorption in FeLoBAL quasars is not a string of individual oddities but a population-level phenomenon concentrated in loitering-outflow FeLoBAL quasars. Fourteen objects show Hα, Hβ, or Hγ absorption; eight of these were not previously known. After accounting for partial covering, which is ubiquitous in BAL quasars and distorts the Balmer optical depth ratios, the authors estimate true H(n=2) column densities from the smallest statistically necessary Balmer line. The resulting differential column density dN/dv is anticorrelated with bolometric luminosity and Eddington ratio, meaning the strongest absorption per unit velocity is found at the

What carries the argument

The essential diagnostic is the ratio of Balmer line optical depths. Atomic physics fixes τ(Hβ)/τ(Hα)=0.14 and τ(Hγ)/τ(Hβ)=0.33; observed ratios larger than these signal partial covering of the emission source. The paper uses the F-test to pick the smallest statistically necessary Balmer line, scales its apparent column by a covering fraction from one of three step-function partial-covering scenarios, and forms dN/dv = column density per velocity width as the measure of opacity available for radiative line driving. The companion classifier is the 'loitering outflow FeLoBAL quasar', defined by low outflow speed (|V_off|<2000 km/s) and compact location, which most of the sample inhabits.

Load-bearing premise

The column density estimates rest on the assumption that step-function partial covering, with the F-test's smallest statistically necessary Balmer line, captures the true absorption geometry; if a more complex geometry (as appears to hold for at least one object) is typical, the quoted column densities and the dN/dv–luminosity anticorrelation could be systematically off.

What would settle it

Recompute the true H(n=2) column densities for the 14 objects with a power-law partial-covering model instead of a step-function covering fraction; if the dN/dv–luminosity and dN/dv–Eddington anticorrelations do not survive, the result is an artifact of the assumed absorption geometry.

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

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If this is right

  • Balmer absorption becomes a practical population diagnostic: most compact-outflow FeLoBAL quasars should show it, and future surveys can target loitering outflows by their FeII morphology.
  • The dN/dv anticorrelation implies radiative line driving naturally produces shallow, broad high-velocity troughs and deep, narrow low-velocity troughs, linking absorption depth to the energy cost of acceleration.
  • The mass-outflow-rate proxy shows no dependence on luminosity or Eddington ratio while momentum flux and kinetic luminosity do, suggesting acceleration, not mass supply, grows with luminosity.
  • Selection effects matter: overlapping-trough quasars may also harbor Balmer absorption that is too broad and shallow to identify, so the sample is biased toward loitering outflows.
  • If FeLoBAL quasars and Little Red Dots share a physical phase, LRD Balmer absorption should be accompanied by other FeLoBAL-like properties, such as metastable helium absorption, weak hot dust, and X-ray weakness, in at least some objects.

Where Pith is reading between the lines

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

  • Beyond the paper: a direct test is to search for metastable helium (He I* λ10830) absorption in Balmer-absorbing Little Red Dots; its presence in FeLoBAL quasars but absence in LRDs would weaken the common-origin story.
  • Beyond the paper: the same dN/dv measure could be applied to existing C IV BAL quasar samples; if the anticorrelation with Eddington ratio holds there, it is a general property of BAL winds rather than a FeLoBAL-specific effect.
  • Beyond the paper: the ˙Mout–luminosity decoupling predicts that multi-epoch observations of the same absorbing gas should show higher-velocity, roughly constant-column features when luminosity increases, without a dramatic change in mass flux.
  • Beyond the paper: because the sample is flux limited, fainter loitering-outflow FeLoBAL quasars at high redshift are underrepresented; deeper spectroscopy of low-luminosity objects should find a higher fraction of Balmer-absorbing outflows than SDSS-selected samples.

Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

3 major / 3 minor

Summary. This paper presents rest-frame optical/NIR spectra of 14 FeLoBAL quasars exhibiting Balmer absorption, of which 8 are new detections. The authors fit the Balmer lines with Gaussian opacity profiles, measure velocity offsets, widths, and optical depths, and estimate apparent and 'true' H(n=2) column densities under three step-function partial-covering scenarios. They report correlations: a weak anticorrelation between Eddington ratio and outflow speed, several anticorrelations between dN/dv (column per velocity width) and L_Bol/Eddington ratio, and a correlation between absorption FWHM and alpha_oi. They discuss similarities between FeLoBAL quasars and Little Red Dots.

Significance. If the correlations hold, the paper establishes Balmer absorption as a systematic feature of loitering-outflow FeLoBAL quasars and provides a new diagnostic (dN/dv) connecting wind properties to accretion rate. The sample is a significant increase over single-object studies. The authors are transparent about the model dependence of column densities, use robust rank correlations with a one-out sensitivity test, and explicitly plan SimBAL follow-up. The LRD comparison is speculative but clearly framed.

major comments (3)
  1. [§3.1, Fig. 2, §4.2] The step-function partial-covering model is demonstrably inadequate for SDSS 1635+1439; the power-law covering model fits better and changes the true column density from 96×10^13 cm^-2 to about 8.8×10^13 cm^-2, a factor of ~11. This object is among the lowest-luminosity and highest-dN/dv in the sample, so the claimed anticorrelations in §4.2 and Fig. 5 may depend critically on the covering model. The one-out test removes the object entirely but does not test the effect of correcting its column to the power-law value. The authors should demonstrate that the dN/dv correlations survive recalculation under power-law covering (or with the planned SimBAL models), or temper the abstract's emphasis on these correlations.
  2. [§3.1, Table 2] The F-test selection of the 'smallest statistically necessary Balmer line' is SNR-dependent. In a flux-limited sample, SNR correlates with luminosity; objects with higher SNR are more likely to have Hβ or Hγ detected and therefore yield larger inferred true columns, while lower-SNR objects may only have Hα and thus lower limits. This could introduce a systematic anticorrelation between dN/dv and luminosity that is not physical. The authors should quantify this bias, e.g., by recomputing the correlations using only Hα apparent columns or by Monte Carlo simulations that vary the F-test outcome with SNR.
  3. [§4.2 and Fig. 5] The dN/dv anticorrelations are presented as a primary result, but they combine two individually weak correlations: column density with L_Bol/Eddington ratio (p≈0.085–0.18) and FWHM with L_Bol (p<0.05). The stronger correlation of the ratio may partially reflect the mathematical combination of these weak trends. The authors should report partial correlations (e.g., column–L_Bol controlling for FWHM) to establish that dN/dv carries independent information, and otherwise present the result with appropriate caveats.
minor comments (3)
  1. [§3.1 (text near Fig. 2)] Typo: 'mdoel' should be 'model'.
  2. [Table 2] The column header 'Statistically Necessary Line Density' is confusing; it should be 'True Column Density (10^13 cm^-2)' with the line used clearly indicated in a separate column or footnote.
  3. [§3.1 and §6] The text says 'we computed three measures of dN/dv', but the description is ambiguous ('the optical depth or column density divided by the line FWHM'). Please specify that the three measures are τ_max/FWHM, apparent column/FWHM, and true column/FWHM.

Circularity Check

0 steps flagged

No significant circularity: the detections and correlations are direct measurements, with prior self-citations used only as context.

full rationale

The paper's central claims are the detection of Balmer absorption in 14 FeLoBAL quasars, eight of them new, and the measured correlations involving outflow velocity, dN/dv, luminosity, Eddington ratio, and alpha_oi. The absorption-line measurements (velocity offset, FWHM, optical depth) come from direct spectral fitting (§3), and the H(n=2) column densities are computed from those fits using standard apparent-optical-depth and step-function partial-covering formulae (§3.1). The bolometric luminosity, black hole mass, and Eddington ratio are derived independently from photometry and the Hβ emission-line FWHM following standard relations (§3.2). The dN/dv correlations with L_Bol and Eddington ratio are therefore correlations between independently measured quantities, not quantities fitted to the same data. The reliance on the authors' prior work—e.g., the loitering-outflow class of H. Choi et al. (2022b) and the alpha_oi–Eddington-ratio connection of K. M. Leighly et al. (2024)—is interpretative context and sample classification, not an input to the equations that yield the reported measurements. The paper explicitly acknowledges the modeling uncertainty in partial covering and the ambiguity in interpreting alpha_oi (footnote 12, §3.1, §4), which are caveats about accuracy, not circularity. The eight new detections are direct discoveries from new NIR spectra, independent of any fitted prediction or self-citation chain. No circular step is apparent.

Axiom & Free-Parameter Ledger

2 free parameters · 5 axioms · 0 invented entities

The sample and measurements are new, but the physical interpretation rests on several simplifications: Gaussian line profiles, step-function partial covering, H-alpha-based redshifts, and treating lower limits as detections. No new physical entities or free-floating parameters are introduced beyond the fitted covering fractions and line profile parameters.

free parameters (2)
  • Partial covering fraction c_f = 0.45 (SDSS 1125+0029), 0.31 (SDSS 1644+5307), 0.21 (SDSS 1723+5553); others use full covering (FC) or not measured
    Fitted per object in the step-function partial covering model to convert the smallest statistically necessary line's apparent column density into a 'true' column density (§3.1, Table 2).
  • Gaussian opacity profile parameters (FWHM, tau_max, velocity offset) = Reported in Table 2 for each object
    The Balmer absorption lines are fitted with Gaussian opacity profiles; the FWHM and peak optical depth are used directly in the dN/dv measures and correlations. The Gaussian shape is an assumption, not a derived quantity.
axioms (5)
  • standard math Relative Balmer optical depths follow the atomic physics ratios tau_Hb/tau_Ha=0.14 and tau_Hg/tau_Hb=0.33
    Used to detect partial covering and to constrain the constrained and partial covering models (§3.1).
  • ad hoc to paper The three step-function partial covering scenarios (P(C+L), PC, FC+PL) bracket the true absorber geometry
    The paper adopts this to estimate true column densities; it acknowledges a power-law covering model is better for at least one object (Fig. 2).
  • ad hoc to paper Balmer absorption lines have Gaussian optical depth profiles
    Assumed for all spectra; the paper notes it may obscure complex kinematics (§3).
  • domain assumption The redshift of 12 objects is set by the peak of the H-alpha emission line
    The paper notes redshift estimation is challenging when low-ionization lines show outflows (§2); an offset in redshift shifts all velocity measurements.
  • domain assumption Measured column densities can be treated as detections rather than censored lower limits in the correlation analysis
    The paper notes all column densities are lower limits when partial covering is ignored, and it chooses not to use survival analysis (§4).

pith-pipeline@v1.3.0-alltime-deepseek · 29841 in / 13306 out tokens · 127107 ms · 2026-08-04T21:55:57.358237+00:00 · methodology

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Cite this review

Pith. "Pith review of Balmer Absorption in Iron Low-Ionization Broad Absorption Line Quasars." pith.science (2026). https://pith.science/paper/RC6GWQS3

@misc{pith2026250907611,
  author       = {Pith},
  title        = {Pith review of: Balmer Absorption in Iron Low-Ionization Broad Absorption Line Quasars},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/RC6GWQS3}},
  note         = {Machine review of arXiv:2509.07611}
}
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read the original abstract

While C IV is the most common absorption line in Broad Absorption Line Quasar spectra, Balmer absorption lines are among the rarest. We present analysis of Balmer absorption in a sample of fourteen iron low-ionization BAL quasars (FeLoBALQs); eight are new identifications. We measured velocity offset, width, and apparent optical depth. The partial covering ubiquitous in BAL quasar spectra alters the measured Balmer optical depth ratios; taking that into account, we estimated the true H(n= 2) column density. We found the anticipated correlation between Eddington ratio and outflow speed, but it is weak in this sample because nearly all of the objects have the low outflow speeds characterizing loitering outflow FeLoBAL quasars (H. Choi et al. 2022b), objects that are also found to have low accretion rates (K. M. Leighly et al. 2022; H. Choi et al. 2022a). Measures of dN/dv, the differential column density with respect to the outflow speed, are anticorrelated with the luminosity and Eddington ratio: the strongest absorption is observed at the lowest speeds in the lowest luminosity objects. The absorption line width is correlated with {\alpha}oi, the F{\lambda} point-to-point slope between 5100A and 3 microns. This parameter is strongly correlated with the Eddington ratio among low-redshift quasars (K. M. Leighly et al. 2024). Balmer absorption lines have been recently found in the spectra of Little Red Dots (LRDs), a class of high-redshift objects discovered by JWST. We note suggestive similarities between LRDs and FeLoBAL quasars in the emission line shape, the presence of steep reddening and a scattered blue continuum, the lack of hot dust emission, and X-ray weakness.

Figures

Figures reproduced from arXiv: 2509.07611 by Donald M. Terndrup, Gordon T. Richards, Hyunseop Choi, Julianna R. Voelker, Karen M. Leighly, Leah K. Morabito, Sarah C. Gallagher.

Figure 1
Figure 1. Figure 1: Examples of the spectra and model fits for two of the fourteen spectra; the remainder are found in the online journal. We note that although the flux density units are given, the spectra are not reliably flux calibrated. Left: SDSS 1439+1628, the object with the lowest optical depth Hα Balmer absorption line. Right: SDSS 1635+1439, the object with the largest optical depth Hα Balmer absorption line. The co… view at source ↗
Figure 2
Figure 2. Figure 2: An illustration of partial covering models in SDSS 1635+1439. The black line shows the uncon￾strained model fit in which the relative Balmer optical depths were allowed to vary independently, yielding an excellent fit but an unphysical model. The blue line shows the best-fitting step-function partial covering model. The Hα line is truncated because the absorption on the continuum is saturated and it is not… view at source ↗
Figure 3
Figure 3. Figure 3: The results of the Spearman rank correlation analysis for the 12-object subsample that covers Hα (left), and for the full 14-object sample (right). The size and color of each marker indicate the sign and p value of the correlation. Anticorrelations are shown in blue, and correlations are shown in red. The shade of the color of each point indicates the significance of the correlation as a continuous variabl… view at source ↗
Figure 4
Figure 4. Figure 4: The anticorrelation between Eddington ratio and velocity offset. The red points mark objects that have Hα in the bandpass; the velocity offset is measured from Hβ for the two objects with blue points. The p values included above the plot were computed for the 12-member sample that includes Hα in the spectrum (p12) and the full sample (p14). The anticorrelation is common among BAL quasars but is weak in thi… view at source ↗
Figure 5
Figure 5. Figure 5: Left: An example of one of the anticorrelations between measures of dN/dv and LBol or Eddington ratio. The log of the significance for this correlation is given at the top of the plot. The circular marker color indicates the absorption line FWHM, which is weakly correlated with LBol, while the circular marker size indicates the log of the true column density, which is weakly anticorrelated with LBol. The e… view at source ↗
Figure 6
Figure 6. Figure 6: Relationship between the absorption line width and αoi, the point-to-point slope between 5100˚A and 3µm. The red points mark objects that have Hα in the bandpass; the velocity offset is measured from Hβ for the two objects with blue points. The horizontal line marks the αoi value from the C. M. Krawczyk et al. (2013) composite spectrum. Objects with values near or below this line have no reddening and weak… view at source ↗

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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. ATLAS. II. Extremely High Incidence of Balmer Line Absorption with Predominant Blueshifts in LRDs: Statistical Insights through Comparison with Type 1 AGNs

    astro-ph.GA 2026-07 conditional novelty 6.0

    Balmer-line absorption occurs in ~35% (14/40) of JWST little-red-dot AGNs, roughly 850x the rate in SDSS type-1 AGNs, with mostly slow blueshifted absorber velocities.

  2. An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars

    astro-ph.GA 2026-07 conditional novelty 6.0

    About 44% of little red dots have hydrogen-alpha absorption from outflowing gas, implying radiatively driven outflows rather than static atmospheres.

Reference graph

Works this paper leans on

137 extracted references · 33 canonical work pages · cited by 2 Pith papers

  1. [1]

    , " * write output.state after.block = add.period write newline

    ENTRY address archivePrefix author booktitle chapter doi edition editor eprint howpublished institution journal key month number organization pages publisher school series title misctitle type volume year version url label extra.label sort.label short.list INTEGERS output.state before.all mid.sentence after.sentence after.block FUNCTION init.state.consts ...

  2. [2]

    write newline

    " write newline "" before.all 'output.state := FUNCTION format.url url empty "" new.block "" url * "" * if FUNCTION format.eprint eprint empty "" archivePrefix empty "" archivePrefix "arXiv" = new.block " " eprint * " " * new.block " " eprint * " " * if if if FUNCTION format.doi doi empty "" " " doi * " " * if FUNCTION format.pid doi empty eprint empty ur...

  3. [3]

    g `ZZ6S( 0kR '<

    thebibliography [1] 20pt to REFERENCES 6pt =0pt \@twocolumntrue 12pt -12pt 10pt plus 3pt =0pt =0pt =1pt plus 1pt =0pt =0pt -12pt =13pt plus 1pt =20pt =13pt plus 1pt \@M =10000 =-1.0em =0pt =0pt 0pt =0pt =1.0em @enumiv\@empty 10000 10000 `\.\@m \@noitemerr \@latex@warning Empty `thebibliography' environment \@ifnextchar \@reference \@latexerr Missing key o...

    2017

  4. [4]

    C., Shemmer , O., et al

    Ahmed , H., Gallagher , S. C., Shemmer , O., et al. 2025, title Exploring the Spectral Energy Distributions of Luminous Broad Absorption Line Quasars at High Redshift , , 985, 207, 10.3847/1538-4357/adca38

    work page doi:10.3847/1538-4357/adca38 2025

  5. [5]

    B., Casey , C

    Akins , H. B., Casey , C. M., Lambrides , E., et al. 2024, title COSMOS-Web: The over-abundance and physical nature of ``little red dots''--Implications for early galaxy and SMBH assembly , arXiv e-prints, arXiv:2406.10341, 10.48550/arXiv.2406.10341

    Pith/arXiv arXiv doi:10.48550/arxiv.2406.10341 2024

  6. [6]

    2010, title Broad Balmer-Line Absorption in SDSS J172341.10+555340.5 , , 62, 1333, 10.1093/pasj/62.5.1333

    Aoki , K. 2010, title Broad Balmer-Line Absorption in SDSS J172341.10+555340.5 , , 62, 1333, 10.1093/pasj/62.5.1333

    doi:10.1093/pasj/62.5.1333 2010

  7. [7]

    2006, title Discovery of H Absorption in the Unusual Broad Absorption Line Quasar SDSS J083942.11+380526.3 , , 651, 84, 10.1086/507438

    Aoki , K., Iwata , I., Ohta , K., et al. 2006, title Discovery of H Absorption in the Unusual Broad Absorption Line Quasar SDSS J083942.11+380526.3 , , 651, 84, 10.1086/507438

    doi:10.1086/507438 2006

  8. [8]

    A., et al

    Arav , N., Kaastra , J., Kriss , G. A., et al. 2005, title X-Ray/Ultraviolet Campaign on the Mrk 279 AGN Outflow: Constraining Inhomogeneous Absorber Models , , 620, 665, 10.1086/425560

    doi:10.1086/425560 2005

  9. [9]

    Baggen , J. F. W., van Dokkum , P., Brammer , G., et al. 2024, title The Small Sizes and High Implied Densities of ``Little Red Dots'' with Balmer Breaks Could Explain Their Broad Emission Lines without an Active Galactic Nucleus , , 977, L13, 10.3847/2041-8213/ad90b8

    doi:10.3847/2041-8213/ad90b8 2024

  10. [10]

    2015, title On the origins of C IV absorption profile diversity in broad absorption line quasars , , 449, 1593, 10.1093/mnras/stv406

    Baskin , A., Laor , A., & Hamann , F. 2015, title On the origins of C IV absorption profile diversity in broad absorption line quasars , , 449, 1593, 10.1093/mnras/stv406

    doi:10.1093/mnras/stv406 2015

  11. [11]

    C., Peterson , B

    Bentz , M. C., Peterson , B. M., Pogge , R. W., Vestergaard , M., & Onken , C. A. 2006, title The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements , , 644, 133, 10.1086/503537

    doi:10.1086/503537 2006

  12. [12]

    D., & Payne , D

    Blandford , R. D., & Payne , D. G. 1982, title Hydromagnetic flows from accretion disks and the production of radio jets. , , 199, 883, 10.1093/mnras/199.4.883

    doi:10.1093/mnras/199.4.883 1982

  13. [13]

    R., Bershady , M

    Blanton , M. R., Bershady , M. A., Abolfathi , B., et al. 2017, title Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe , , 154, 28, 10.3847/1538-3881/aa7567

    doi:10.3847/1538-3881/aa7567 2017

  14. [14]

    Boroson , T. A. 2002, title Black Hole Mass and Eddington Ratio as Drivers for the Observable Properties of Radio-loud and Radio-quiet QSOs , , 565, 78, 10.1086/324486

    doi:10.1086/324486 2002

  15. [15]

    A., & Green , R

    Boroson , T. A., & Green , R. F. 1992, title The Emission-Line Properties of Low-Redshift Quasi-stellar Objects , , 80, 109, 10.1086/191661

    doi:10.1086/191661 1992

  16. [16]

    S., Laurent-Muehleisen , S

    Brotherton , M. S., Laurent-Muehleisen , S. A., Becker , R. H., et al. 2005, title Chandra X-Ray Observations of Radio-Loud Broad Absorption Line Quasars , , 130, 2006, 10.1086/496948

    work page doi:10.1086/496948 2005

  17. [17]

    S., Tran , H

    Brotherton , M. S., Tran , H. D., van Breugel , W., Dey , A., & Antonucci , R. 1997, title Spectropolarimetry of FIRST Broad Absorption Line Quasars , , 487, L113, 10.1086/310898

    work page doi:10.1086/310898 1997

  18. [18]

    A., Clayton , G

    Cardelli , J. A., Clayton , G. C., & Mathis , J. S. 1988, title The determination of ultraviolet extinction from the optical and near-infrared , , 329, L33

    1988

  19. [19]

    C., Magnier , E

    Chambers , K. C., Magnier , E. A., Metcalfe , N., et al. 2016, title The Pan-STARRS1 Surveys , arXiv e-prints, arXiv:1612.05560, 10.48550/arXiv.1612.05560

    Pith/arXiv arXiv doi:10.48550/arxiv.1612.05560 2016

  20. [20]

    Chen , K., Li , Z., Inayoshi , K., & Ho , L. C. 2025, title Dust Budget Crisis in Little Red Dots , arXiv e-prints, arXiv:2505.22600, 10.48550/arXiv.2505.22600

    doi:10.48550/arxiv.2505.22600 2025

  21. [21]

    M., Dabbieri , C., et al

    Choi , H., Leighly , K. M., Dabbieri , C., et al. 2022 a , title The Physical Properties of Low-redshift FeLoBAL Quasars. III. The Location and Geometry of the Outflows , , 936, 110 (Paper III), 10.3847/1538-4357/ac854c

    doi:10.3847/1538-4357/ac854c 2022

  22. [22]

    M., Terndrup , D

    Choi , H., Leighly , K. M., Terndrup , D. M., et al. 2022 b , title The Physical Properties of Low-redshift FeLoBAL Quasars. I. Spectral-synthesis Analysis of the Broad Absorption-line (BAL) Outflows Using SimBAL , , 937, 74 (Paper I), 10.3847/1538-4357/ac61d9

    doi:10.3847/1538-4357/ac61d9 2022

  23. [23]

    M., Terndrup , D

    Choi , H., Leighly , K. M., Terndrup , D. M., Gallagher , S. C., & Richards , G. T. 2020, title Discovery of a Remarkably Powerful Broad Absorption-line Quasar Outflow in SDSS J135246.37+423923.5 , , 891, 53, 10.3847/1538-4357/ab6f72

    doi:10.3847/1538-4357/ab6f72 2020

  24. [24]

    M., & Vestergaard , M

    Collin , S., Kawaguchi , T., Peterson , B. M., & Vestergaard , M. 2006, title Systematic effects in measurement of black hole masses by emission-line reverberation of active galactic nuclei: Eddington ratio and inclination , , 456, 75, 10.1051/0004-6361:20064878

    doi:10.1051/0004-6361:20064878 2006

  25. [25]

    C., Vacca , W

    Cushing , M. C., Vacca , W. D., & Rayner , J. T. 2004, title Spextool: A Spectral Extraction Package for SpeX, a 0.8-5.5 Micron Cross-Dispersed Spectrograph , , 116, 362, 10.1086/382907

    doi:10.1086/382907 2004

  26. [26]

    T., & Arav , N

    de Kool , M., Korista , K. T., & Arav , N. 2002, title The Effects of Inhomogeneous Absorbers on the Formation of Intrinsic Quasar Absorption Lines , , 580, 54, 10.1086/343107

    work page doi:10.1086/343107 2002

  27. [27]

    D'Eugenio , F., Juod z balis , I., Ji , X., et al. 2025, title JADES and BlackTHUNDER: rest-frame Balmer-line absorption and the local environment in a Little Red Dot at z = 5 , arXiv e-prints, arXiv:2506.14870, 10.48550/arXiv.2506.14870

    doi:10.48550/arxiv.2506.14870 2025

  28. [28]

    A., Brotherton , M

    DiPompeo , M. A., Brotherton , M. S., Becker , R. H., et al. 2010, title Spectropolarimetry of Radio-selected Broad Absorption Line Quasars , , 189, 83, 10.1088/0067-0049/189/1/83

    work page doi:10.1088/0067-0049/189/1/83 2010

  29. [29]

    A., Brotherton , M

    DiPompeo , M. A., Brotherton , M. S., & De Breuck , C. 2011, title Very Large Telescope Spectropolarimetry of Broad Absorption Line QSOs , , 193, 9, 10.1088/0067-0049/193/1/9

    work page doi:10.1088/0067-0049/193/1/9 2011

  30. [30]

    A., Brotherton , M

    DiPompeo , M. A., Brotherton , M. S., & De Breuck , C. 2013 a , title The orientation and polarization of broad absorption line quasars , , 428, 1565, 10.1093/mnras/sts137

    work page doi:10.1093/mnras/sts137 2013

  31. [31]

    A., Runnoe , J

    DiPompeo , M. A., Runnoe , J. C., Brotherton , M. S., & Myers , A. D. 2013 b , title An Infrared Excess Identified in Radio-loud Broad Absorption Line Quasars , , 762, 111, 10.1088/0004-637X/762/2/111

    work page doi:10.1088/0004-637x/762/2/111 2013

  32. [32]

    H., Joyce , R

    Elias , J. H., Joyce , R. R., Liang , M., et al. 2006 a , title Design of the Gemini near-infrared spectrograph , in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 6269, Ground-based and Airborne Instrumentation for Astronomy, ed. I. S. McLean & M. Iye , 62694C, 10.1117/12.671817

    doi:10.1117/12.671817 2006

  33. [33]

    H., Rodgers , B., Joyce , R

    Elias , J. H., Rodgers , B., Joyce , R. R., et al. 2006 b , title Performance of the Gemini near-infrared spectrograph , in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 6269, Ground-based and Airborne Instrumentation for Astronomy, ed. I. S. McLean & M. Iye , 626914, 10.1117/12.671765

    doi:10.1117/12.671765 2006

  34. [34]

    Elitzur , M., & Ho , L. C. 2009, title On the Disappearance of the Broad-Line Region in Low-Luminosity Active Galactic Nuclei , , 701, L91, 10.1088/0004-637X/701/2/L91

    doi:10.1088/0004-637x/701/2/l91 2009

  35. [35]

    2006, title The AGN-obscuring Torus: The End of the ``Doughnut'' Paradigm? , , 648, L101, 10.1086/508158

    Elitzur , M., & Shlosman , I. 2006, title The AGN-obscuring Torus: The End of the ``Doughnut'' Paradigm? , , 648, L101, 10.1086/508158

    doi:10.1086/508158 2006

  36. [36]

    2012, title Direct Evidence for Termination of Obscured Star Formation by Radiatively Driven Outflows in Reddened QSOs , , 745, 178, 10.1088/0004-637X/745/2/178

    Farrah , D., Urrutia , T., Lacy , M., et al. 2012, title Direct Evidence for Termination of Obscured Star Formation by Radiatively Driven Outflows in Reddened QSOs , , 745, 178, 10.1088/0004-637X/745/2/178

    doi:10.1088/0004-637x/745/2/178 2012

  37. [37]

    J., Chatzikos , M., Guzm \'a n , F., et al

    Ferland , G. J., Chatzikos , M., Guzm \'a n , F., et al. 2017, title The 2017 Release Cloudy , , 53, 385. 1705.10877

    Pith/arXiv arXiv 2017

  38. [38]

    Fynbo , J. P. U., Krogager , J. K., Venemans , B., et al. 2013, title Optical/Near-infrared Selection of Red Quasi-stellar Objects: Evidence for Steep Extinction Curves toward Galactic Centers? , , 204, 6, 10.1088/0067-0049/204/1/6

    doi:10.1088/0067-0049/204/1/6 2013

  39. [39]

    C., Brandt , W

    Gallagher , S. C., Brandt , W. N., Chartas , G., & Garmire , G. P. 2002, title X-Ray Spectroscopy of Quasi-Stellar Objects with Broad Ultraviolet Absorption Lines , , 567, 37, 10.1086/338485

    work page doi:10.1086/338485 2002

  40. [40]

    C., Brandt , W

    Gallagher , S. C., Brandt , W. N., Chartas , G., et al. 2006, title An Exploratory Chandra Survey of a Well-defined Sample of 35 Large Bright Quasar Survey Broad Absorption Line Quasars , , 644, 709, 10.1086/503762

    doi:10.1086/503762 2006

  41. [41]

    C., Everett , J

    Gallagher , S. C., Everett , J. E., Abado , M. M., & Keating , S. K. 2015, title Investigating the structure of the windy torus in quasars , , 451, 2991, 10.1093/mnras/stv1126

    doi:10.1093/mnras/stv1126 2015

  42. [42]

    C., Hines , D

    Gallagher , S. C., Hines , D. C., Blaylock , M., et al. 2007 a , title Radio through X-Ray Spectral Energy Distributions of 38 Broad Absorption Line Quasars , , 665, 157, 10.1086/519438

    work page doi:10.1086/519438 2007

  43. [43]

    C., Richards , G

    Gallagher , S. C., Richards , G. T., Lacy , M., et al. 2007 b , title An Investigation into the Effects of Luminosity on the Mid-Infrared Spectral Energy Distributions of Radio-quiet Quasars , , 661, 30, 10.1086/513733

    work page doi:10.1086/513733 2007

  44. [44]

    S., Cales , S., et al

    Ganguly , R., Brotherton , M. S., Cales , S., et al. 2007, title Outflows and the Physical Properties of Quasars , , 665, 990, 10.1086/519759

    doi:10.1086/519759 2007

  45. [45]

    C., & Churchill , C

    Ganguly , R., Eracleous , M., Charlton , J. C., & Churchill , C. W. 1999, title Intrinsic Narrow Absorption Lines in Keck HIRES Spectra of a Sample of Six Quasars , , 117, 2594, 10.1086/300882

    work page doi:10.1086/300882 1999

  46. [46]

    R., Brandt , W

    Gibson , R. R., Brandt , W. N., Gallagher , S. C., & Schneider , D. P. 2009 a , title X-ray Insights into the Physics of Mini-BAL Quasar Outflows , ApJ, 696, 924, 10.1088/0004-637X/696/1/924

    work page doi:10.1088/0004-637x/696/1/924 2009

  47. [47]

    R., Jiang , L., Brandt , W

    Gibson , R. R., Jiang , L., Brandt , W. N., et al. 2009 b , title A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5 , , 692, 758, 10.1088/0004-637X/692/1/758

    doi:10.1088/0004-637x/692/1/758 2009

  48. [48]

    2008, title On the absorption of X-ray bright broad absorption line quasars , A& A, 491, 425, 10.1051/0004-6361:200810363

    Giustini , M., Cappi , M., & Vignali , C. 2008, title On the absorption of X-ray bright broad absorption line quasars , A& A, 491, 425, 10.1051/0004-6361:200810363

    work page doi:10.1051/0004-6361:200810363 2008

  49. [49]

    2019, title A global view of the inner accretion and ejection flow around super massive black holes

    Giustini , M., & Proga , D. 2019, title A global view of the inner accretion and ejection flow around super massive black holes. Radiation-driven accretion disk winds in a physical context , , 630, A94, 10.1051/0004-6361/201833810

    doi:10.1051/0004-6361/201833810 2019

  50. [50]

    S., Gallagher , S

    Green , K. S., Gallagher , S. C., Leighly , K. M., et al. 2023, title Investigating the Origin of the Absorption-line Variability in the Narrow-line Seyfert 1 Galaxy WPVS 007 , , 953, 186, 10.3847/1538-4357/ace2c4

    work page doi:10.3847/1538-4357/ace2c4 2023

  51. [51]

    J., Aldcroft , T

    Green , P. J., Aldcroft , T. L., Mathur , S., Wilkes , B. J., & Elvis , M. 2001, title A Chandra Survey of Broad Absorption Line Quasars , , 558, 109, 10.1086/322311

    doi:10.1086/322311 2001

  52. [52]

    E., Labbe , I., Goulding , A

    Greene , J. E., Labbe , I., Goulding , A. D., et al. 2024, title UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5 , ApJ, 964, 39, 10.3847/1538-4357/ad1e5f

    doi:10.3847/1538-4357/ad1e5f 2024

  53. [53]

    2004, title A Complete Sample of Soft X-Ray-selected AGNs

    Grupe , D. 2004, title A Complete Sample of Soft X-Ray-selected AGNs. II. Statistical Analysis , , 127, 1799, 10.1086/382516

    doi:10.1086/382516 2004

  54. [54]

    D., et al

    Hagen , S., Done , C., Silverman , J. D., et al. 2024, title Systematic collapse of the accretion disc across the supermassive black hole population , MNRAS, 534, 2803, 10.1093/mnras/stae2272

    doi:10.1093/mnras/stae2272 2024

  55. [55]

    Hall , P. B. 2007, title A Quasar with Broad Absorption in the Balmer Lines , , 133, 1271, 10.1086/511272

    doi:10.1086/511272 2007

  56. [56]

    B., Anderson , S

    Hall , P. B., Anderson , S. F., Strauss , M. A., et al. 2002, title Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey , , 141, 267, 10.1086/340546

    doi:10.1086/340546 2002

  57. [57]

    1998, title Broad P V Absorption in the QSO PG 1254+047: Column Densities, Ionizations, and Metal Abundances in Broad Absorption Line Winds , , 500, 798, 10.1086/305776

    Hamann , F. 1998, title Broad P V Absorption in the QSO PG 1254+047: Column Densities, Ionizations, and Metal Abundances in Broad Absorption Line Winds , , 500, 798, 10.1086/305776

    work page doi:10.1086/305776 1998

  58. [58]

    2019, title On the structure and energetics of quasar broad absorption-line outflows , , 483, 1808, 10.1093/mnras/sty2900

    Hamann , F., Herbst , H., Paris , I., & Capellupo , D. 2019, title On the structure and energetics of quasar broad absorption-line outflows , , 483, 1808, 10.1093/mnras/sty2900

    doi:10.1093/mnras/sty2900 2019

  59. [59]

    C., & Foltz , C

    Hewett , P. C., & Foltz , C. B. 2003, title The Frequency and Radio Properties of Broad Absorption Line Quasars , , 125, 1784, 10.1086/368392

    doi:10.1086/368392 2003

  60. [60]

    Hopkins , P. F. 2025, title Multi-Phase Thermal Structure & The Origin of the Broad-Line Region, Torus, and Corona in Magnetically-Dominated Accretion Disks , The Open Journal of Astrophysics, 8, 56, 10.33232/001c.137969

    doi:10.33232/001c.137969 2025

  61. [61]

    B., Crenshaw , D

    Hutchings , J. B., Crenshaw , D. M., Kraemer , S. B., et al. 2002, title Balmer and He I Absorption in the Nuclear Spectrum of NGC 4151 , AJ, 124, 2543, 10.1086/344080

    doi:10.1086/344080 2002

  62. [62]

    Inayoshi , K., & Maiolino , R. 2025, title Extremely Dense Gas around Little Red Dots and High-redshift Active Galactic Nuclei: A Nonstellar Origin of the Balmer Break and Absorption Features , ApJL, 980, L27, 10.3847/2041-8213/adaebd

    doi:10.3847/2041-8213/adaebd 2025

  63. [63]

    P., Richards , G

    Jester , S., Schneider , D. P., Richards , G. T., et al. 2005, title The Sloan Digital Sky Survey View of the Palomar-Green Bright Quasar Survey , , 130, 873, 10.1086/432466

    doi:10.1086/432466 2005

  64. [64]

    2012, title Discovery of Balmer broad absorption lines in the quasar LBQS 1206+1052 , Research in Astronomy and Astrophysics, 12, 369, 10.1088/1674-4527/12/4/002

    Ji , T., Wang , T.-G., Zhou , H.-Y., & Wang , H.-Y. 2012, title Discovery of Balmer broad absorption lines in the quasar LBQS 1206+1052 , Research in Astronomy and Astrophysics, 12, 369, 10.1088/1674-4527/12/4/002

    work page doi:10.1088/1674-4527/12/4/002 2012

  65. [65]

    2013, title Anomalously Steep Reddening Law in Quasars: An Exceptional Example Observed in IRAS 14026+4341 , , 145, 157, 10.1088/0004-6256/145/6/157

    Jiang , P., Zhou , H., Ji , T., et al. 2013, title Anomalously Steep Reddening Law in Quasars: An Exceptional Example Observed in IRAS 14026+4341 , , 145, 157, 10.1088/0004-6256/145/6/157

    doi:10.1088/0004-6256/145/6/157 2013

  66. [66]

    R., & Cottis , C

    Knigge , C., Scaringi , S., Goad , M. R., & Cottis , C. E. 2008, title The intrinsic fraction of broad-absorption line quasars , , 386, 1426, 10.1111/j.1365-2966.2008.13081.x

    arXiv 2008

  67. [67]

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

    Kocevski , D. D., Onoue , M., Inayoshi , K., et al. 2023, title Hidden Little Monsters: Spectroscopic Identification of Low-mass, Broad-line AGNs at z > 5 with CEERS , ApJL, 954, L4, 10.3847/2041-8213/ace5a0

    doi:10.3847/2041-8213/ace5a0 2023

  68. [68]

    D., Finkelstein , S

    Kocevski , D. D., Finkelstein , S. L., Barro , G., et al. 2025, title The Rise of Faint, Red Active Galactic Nuclei at z > 4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields , ApJ, 986, 126, 10.3847/1538-4357/adbc7d

    doi:10.3847/1538-4357/adbc7d 2025

  69. [69]

    Konigl , A., & Kartje , J. F. 1994, title Disk-driven Hydromagnetic Winds as a Key Ingredient of Active Galactic Nuclei Unification Schemes , , 434, 446, 10.1086/174746

    doi:10.1086/174746 1994

  70. [70]

    C ., & Dimitrijevi \'c , M

    Kova c evi \'c , J., Popovi \'c , L. C ., & Dimitrijevi \'c , M. S. 2010, title Analysis of Optical Fe II Emission in a Sample of Active Galactic Nucleus Spectra , , 189, 15, 10.1088/0067-0049/189/1/15

    doi:10.1088/0067-0049/189/1/15 2010

  71. [71]

    M., Richards , G

    Krawczyk , C. M., Richards , G. T., Gallagher , S. C., et al. 2015, title Mining for Dust in Type 1 Quasars , , 149, 203, 10.1088/0004-6256/149/6/203

    work page doi:10.1088/0004-6256/149/6/203 2015

  72. [72]

    M., Richards , G

    Krawczyk , C. M., Richards , G. T., Mehta , S. S., et al. 2013, title Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars , , 206, 4, 10.1088/0067-0049/206/1/4

    doi:10.1088/0067-0049/206/1/4 2013

  73. [73]

    K., Geier , S., Fynbo , J

    Krogager , J. K., Geier , S., Fynbo , J. P. U., et al. 2015, title The High A _ V Quasar Survey: Reddened Quasi-Stellar Objects Selected from Optical/Near-Infrared Photometry II , , 217, 5, 10.1088/0067-0049/217/1/5

    doi:10.1088/0067-0049/217/1/5 2015

  74. [74]

    Laor , A., & Brandt , W. N. 2002, title The Luminosity Dependence of Ultraviolet Absorption in Active Galactic Nuclei , , 569, 641, 10.1086/339476

    work page doi:10.1086/339476 2002

  75. [75]

    J., Almaini , O., et al

    Lawrence , A., Warren , S. J., Almaini , O., et al. 2007, title The UKIRT Infrared Deep Sky Survey (UKIDSS) , , 379, 1599, 10.1111/j.1365-2966.2007.12040.x

    arXiv 2007

  76. [76]

    Leighly , K. M. 2004, title Hubble Space Telescope STIS Ultraviolet Spectral Evidence of Outflow in Extreme Narrow-Line Seyfert 1 Galaxies. II. Modeling and Interpretation , , 611, 125, 10.1086/422089

    doi:10.1086/422089 2004

  77. [77]

    M., Choi , H., DeFrancesco , C., et al

    Leighly , K. M., Choi , H., DeFrancesco , C., et al. 2022, title The Physical Properties of Low-redshift FeLoBAL Quasars. II. The Rest-frame Optical Emission Line Properties , , 935, 92 (Paper II), 10.3847/1538-4357/ac7e50

    doi:10.3847/1538-4357/ac7e50 2022

  78. [78]

    M., Choi , H., Eracleous , M., et al

    Leighly , K. M., Choi , H., Eracleous , M., et al. 2024, title The Physical Properties of Low-redshift FeLoBAL Quasars. IV. Optical Near-IR Spectral Energy Distributions and Near-IR Variability Properties , , 966, 87, 10.3847/1538-4357/ad2f2a

    work page doi:10.3847/1538-4357/ad2f2a 2024

  79. [79]

    M., Dietrich , M., & Barber , S

    Leighly , K. M., Dietrich , M., & Barber , S. 2011, title The Discovery of the First He I 10830 Broad Absorption Line Quasar , , 728, 94

    2011

  80. [80]

    M., Halpern , J

    Leighly , K. M., Halpern , J. P., Jenkins , E. B., et al. 2007, title The Intrinsically X-Ray Weak Quasar PHL 1811. I. X-Ray Observations and Spectral Energy Distribution , , 663, 103, 10.1086/518017

    doi:10.1086/518017 2007

Showing first 80 references.