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REVIEW 4 major objections 4 minor 69 references

A Wandering 35,000-Solar-Mass Black Hole Fed by a Gravitational Wake

T0 review · 4 major / 4 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read UGCA320-IMBH is a 35,000-solar-mass black hole wandering outside its host galaxy's disc, accreting from a Bondi-Hoyle-Lyttleton gravitational wake rather than from nuclear gas channels.

desk verdict A strong IMBH candidate whose BHL wake interpretation is over-claimed; deserves review but needs a host-outflow model and data release. read the letter →

arxiv 2608.10719 v1 pith:ZNDWX2PF submitted 2026-08-11 astro-ph.GA

Xin Li , Yong Shi , Fuyan Bian , Junfeng Wang , Shude Mao , Qiusheng Gu , Yifei Jin , Yanmei Chen
show 3 more authors
Zhiyuan Zheng Qinwei Yuan Xiaoling Yu
This is my paper · ORCID
classification astro-ph.GA
keywords intermediate-massblackholewanderingBondi-Hoyle-Lyttletonaccretiongravitationalwakedwarfgalaxychanging-lookAGNbroad-lineemissionUGCA320
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

This paper claims to have found the first direct evidence that a wandering intermediate-mass black hole can grow by capturing gas from the gravitational wake it creates while moving through its host galaxy's interstellar medium. The object, UGCA320-IMBH, sits outside the star-forming disc of the dwarf galaxy UGCA 320 and is argued to be a roughly 35,000-solar-mass black hole on the basis of broad Balmer emission, a compact optical continuum, multi-year variability, and a power-law ultraviolet-to-optical spectrum. Multi-epoch spectroscopy shows three gas components that match the predicted Bondi-Hoyle-Lyttleton flow pattern: a blueshifted low-density inflow, a redshifted dense downstream wake, and optically thick absorbing clumps inside the capture radius that switch the broad lines on and off. If correct, this establishes a direct growth channel for seed black holes that spend most of their time away from galactic nuclei.

What carries the argument

Bondi-Hoyle-Lyttleton (BHL) accretion is the mechanism that carries the argument: gravitational focusing of ambient gas by a moving black hole creates a dense downstream wake within a capture radius of order $GM/c_s^2$, from which gas is captured and accreted. The BHL framework provides the predicted three-component gas structure—low-density upstream flow, dense downstream wake, and inner absorbing accretion flow—that maps directly onto the observed velocity and density components, and it supplies the capture-radius estimate that places the absorbing clumps inside the accretion flow.

What would settle it

A higher-resolution (sub-arcsecond) integral-field observation of the ionized gas around UGCA320-IMBH that resolves the two narrow-line components and finds they are not arranged as a dipole oriented along the black hole's direction of motion would falsify the wake interpretation, as would a demonstration that the redshifted dense component's kinematics match the known galaxy-scale HI outflow rather than trailing the black hole; a future X-ray detection showing a column density much lower than the predicted $>10^{23}$ cm$^{-2}$ would also weaken the absorber-in-the-accretion-flow claim.

Watch

Extended reading notes

Core claim

UGCA320-IMBH is an off-nuclear point source in the dwarf irregular galaxy UGCA 320 whose spectroscopic, photometric, and variability properties identify it as an accreting intermediate-mass black hole of approximately $3.5\times10^4\ M_\odot$. The paper's central claim is that its gas supply comes from Bondi-Hoyle-Lyttleton accretion: as the black hole moves through the interstellar medium, gravitational focusing creates a dense wake behind it, and the captured gas feeds the black hole. The evidence is the simultaneous detection, in a single X-shooter spectrum, of the three predicted flow components: a blueshifted low-density upstream flow ($n_e\sim40$ cm$^{-3}$ from the [SII] doublet), a redshifted high-density downstream wake (FeII and CaII emission requiring $n_e$ above roughly $10^6$ cm$^{-3}$), and blueshifted optically thick absorbers with column density greater than $5\times10^{22}$ cm$^{-2}$ lying inside the approximately 0.3 pc capture radius. The changing-look behavior of the broad Balmer lines over a few years is attributed to these absorbing clumps crossing the line of sight.

Load-bearing premise

The interpretation assumes that the blueshifted gas is physically upstream and the redshifted gas is physically downstream along the black hole's direction of motion, even though at the 28 pc resolution the components are blended and the host galaxy already has an outflow that could produce a similar velocity structure without a wake.

Editorial extensions

If this is right

  • Wandering intermediate-mass black holes can accrete efficiently without being at a galactic center, so off-nuclear seed black holes have a viable path to grow.
  • Changing-look broad-line variability in some active galactic nuclei may be caused by clumps in a BHL accretion flow crossing the line of sight, not only by changes in the intrinsic accretion rate.
  • The BHL wake can concentrate gas to densities above $10^6$ cm$^{-3}$ within a parsec of the black hole, providing a natural emission region for FeII and CaII lines around low-luminosity accreting black holes.
  • Similar spectroscopic signatures—blueshifted low-density narrow emission, redshifted dense narrow emission, and blueshifted absorption inside the capture radius—are expected around other wandering intermediate-mass black holes.
  • If this channel is widespread, it contributes to the early growth of seed black holes before they sink into galactic nuclei and assemble supermassive black holes.

Reading between the lines

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

  • The same BHL signature could be searched for in surveys of dwarf galaxies by looking for off-nuclear point sources with oppositely shifted narrow emission lines and changing-look broad Balmer lines, rather than only at nuclear activity.
  • The proposed absorber at roughly 0.06 pc with column density above $5\times10^{22}$ cm$^{-2}$ is a testable prediction: future X-ray observations with better sensitivity should reveal a heavily absorbed or eclipsing source, and high-resolution radio or infrared mapping could spatially resolve the wake.
  • The interpretation would be weakened if the redshifted dense component is instead part of the known galaxy-scale HI outflow in UGCA 320 (ref 14), since that outflow can produce similar velocity structure; distinguishing these requires mapping the gas on sub-28 pc scales.
  • The black hole mass relies on the broad-line scaling relation calibrated on more massive active galactic nuclei; an independent dynamical mass measurement or reverberation mapping would test the $3.5\times10^4\ M_\odot$ value.
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Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

4 major / 4 minor

Summary. The paper reports the discovery of an off-nuclear accreting intermediate-mass black hole (IMBH) in the dwarf galaxy UGCA 320, with a nominal mass of 3.5e4 solar masses, and claims that its gas supply is provided by Bondi–Hoyle–Lyttleton (BHL) accretion from a gravitational wake. The IMBH identification rests on broad H-alpha emission (FWHM 854 km/s), a compact HST continuum counterpart, 14-year optical variability, a power-law SED with a Balmer-edge break, and saturated Balmer absorption lines interpreted as non-stellar. The BHL wake interpretation is based on multi-epoch spectroscopy that reveals a blueshifted, low-density emission component (attributed to upstream flow), a redshifted, dense FeII/CaII emission component (attributed to the downstream wake), and a blueshifted absorption system (attributed to clumps within the BHL capture radius).

Significance. If the BHL wake claim holds, this would be the first direct evidence for a previously unobserved growth channel for wandering intermediate-mass black holes, with direct implications for seed black hole growth and the assembly of supermassive black holes. The identification of the IMBH itself appears well supported by the broad-line emission, compact continuum, variability, and non-stellar absorption features; this alone would be a notable result. However, the paper's central novelty—the BHL wake interpretation—currently rests on a kinematic assumption that is not uniquely supported given the known galaxy-scale HI outflow in UGCA 320. The manuscript is data-rich and carefully presented, with multi-epoch spectroscopy, astrometric alignment, SED fitting, and CLOUDY modeling, but the wake claim needs substantially more quantitative support before it can be accepted as established.

major comments (4)
  1. [Main text, bullet 'Downstream wake with high density' and Fig. 3] The assignment of the blueshifted [OIII]/[SII] component as upstream and the redshifted FeII/CaII component as downstream assumes that line-of-sight velocity ordering directly maps onto physical upstream/downstream ordering in the BHL flow. This is load-bearing for the central BHL claim but is not demonstrated. At the MUSE PSF of 28 pc and the X-shooter 1-arcsec aperture (~29 pc), the components are spatially blended with the surrounding ISM; the wake scale is only ~0.3 pc. The host galaxy is known to host a galaxy-scale HI outflow along the minor axis (ref 14), which can produce +-20-30 km/s line-of-sight velocity structure without any BH wake. The observed +-27 km/s components are consistent with such an outflow, and no host-galaxy kinematic model is subtracted before the wake assignment. I request a quantitative test of the outflow alternative (e.g., modeling the expected emission-line ratios and velocity fields from the HI outflow) or a spatial/kinematic decomposition that can distinguish the two.
  2. [Main text, bullet 'Downstream wake with high density'] The claim that the redshifted component traces a dense (>10^6 cm^-3) downstream wake rests on the presence of permitted FeII and CaII emission. These lines are not unique to BHL wakes; they are observed in AGN outflows and dense ISM clumps. The density inference is not quantified with a line-ratio analysis, and the assumed association of this gas with a sub-pc wake is not justified given that the extraction aperture includes ~29 pc of host galaxy. The coexistence of FeII and CaII could equally be produced by a dense cloud embedded in the known HI outflow. A photoionization modeling of the FeII/CaII line ratios to constrain the density, and a discussion of alternative dense-gas environments, is needed to support this identification.
  3. [Main text, bullet 'Dense clumps tracing the accretion flow'] The location of the absorbing clumps within the BHL capture radius (Keplerian radius ~0.06 pc vs capture radius ~0.3 pc) is derived from the assumption that the absorber's orbital velocity equals the observed line-of-sight velocity of ~50 km/s. This is an ad-hoc assumption with no independent support. The same absorption features (blueshifted Balmer series, FeI/II, CaII) could arise in the known galaxy-scale HI outflow, which would place the gas far outside the BHL radius. The changing-look variability over a few years does not uniquely require an eclipsing absorber within 0.06 pc; intrinsic variability of the accretion flow is an alternative that is not ruled out. The paper should either present simulations or an independent observational test that ties the absorption to the BHL accretion flow, or explicitly present this as a speculative interpretation rather than a firm conclusion.
  4. [Methods 3.2 and Extended Data Fig. 4] The Balmer absorption model uses Cloudy with an assumed ionization parameter log U = -1.5 and complete coverage (f_c = 1), and the resulting constraints on n_H and N_H are presented as lower limits. However, the absorber's blueshifted velocity of -50 km/s is not part of the model, and the possibility that the absorption arises in a galaxy-scale outflow is not considered. The section would benefit from a direct comparison of the observed absorption kinematics and column density with the predictions of an outflow model, since the known HI outflow in UGCA 320 is a plausible alternative to a BHL accretion flow.
minor comments (4)
  1. [Main text, first paragraph] The black hole mass is quoted as 3.5e4 M_sun without an uncertainty; please provide the propagated uncertainty from the Reines et al. scaling relation used for its derivation.
  2. [Methods 7.2] There is a typo in the text: 'temperature (Teff) from 3,500 k to 50,000 k' should use uppercase K for Kelvin. Additionally, the statement 'logg from 0.0 to 5.0 cm s^-2' should read 'cm s^-2' consistently.
  3. [Fig. 3 caption] The phrase 'the red dashed curves overlapped on the Hδ, Hγ, Hβ, and Hα' would be clearer as 'the red dashed curves overplotted on ...'.
  4. [Methods 7.1] The SED fitting parameters (α, f_c, A) are reported without uncertainties or a goodness-of-fit statistic; providing these would strengthen the comparison with stellar models.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the black-hole mass, AGN interpretation, and BHL-wake identification rest on external scaling relations, explicit model comparisons, and independent spectral diagnostics.

full rationale

The paper's derivation chain is self-contained and does not reduce any prediction to its own inputs. The black-hole mass is derived from the broad Hα FWHM using the external Reines et al. (2013) scaling relation (ref 20), not from the wake model. The AGN interpretation is supported by a compact HST continuum, long-term variability, and a power-law SED that is explicitly compared against stellar atmosphere models and rejected on independent grounds (Extended Data Fig. 2). The gravitational-wake identification uses separate spectroscopic diagnostics: the low density of the blueshifted component is inferred from the [SII] doublet ratio, while the high density of the redshifted component is inferred from the presence of permitted FeII and CaII emission, both external atomic-physics diagnostics. The absorber-location argument is internally consistent but is not used as evidence for the wake itself. The known galaxy-scale HI outflow (ref 14) is a plausible alternative interpretation of the velocity structure, but that is a scientific-assumption concern, not circularity. The only notable self-citation, ref 11 (DGIS), is used for data provenance and MUSE reduction details, not as load-bearing evidence for the central claim. No fitted parameter is renamed as a prediction, nor is any uniqueness claim imported from the authors' prior work.

Assumptions & free parameters 5 free parameters · 6 assumptions · 0 invented entities

The paper's interpretation rests on standard scaling relations, photoionization modeling choices, and an assumed spatial ordering of gas components. No new physical entities are introduced.

free parameters (5)
  • AGN power-law spectral index alpha = not stated
    Fitted to the UV-to-optical SED in Methods 7.1 together with normalization A and covering fraction f_c.
  • Covering fraction f_c of the Balmer-edge absorber = not stated (SED fit)
    Determines the transmitted fraction blueward of 3646 Angstroms; fitted alongside alpha and A.
  • SED normalization A = not stated
    Scales the AGN power-law model to the observed photometry.
  • Absorber hydrogen density n_H = ~1e11 to 1e12 cm^-3
    Chosen to match Balmer break strength and H-gamma equivalent width in the CLOUDY grid; a model interpretation, not a direct measurement.
  • Absorber hydrogen column density N_H = ~5e22 cm^-2 (lower limit)
    Required to reproduce the Balmer break and absorption equivalent widths; the X-ray non-detection independently suggests N_H > 1e23 cm^-2.
assumptions (6)
  • domain assumption The broad H-alpha line width and luminosity trace the black hole mass through the Reines et al. single-epoch virial scaling relation.
    Used to derive 3.5e4 solar masses in the second paragraph; assumes a virialized broad-line region and a type-1 geometry in a low-metallicity dwarf.
  • ad hoc to paper Line-of-sight velocity ordering maps directly onto physical upstream and downstream ordering in the BHL flow.
    The blueshifted narrow component is called upstream and the redshifted component downstream, but the flow geometry is not spatially resolved.
  • ad hoc to paper The absorbing clumps move at roughly the observed line-of-sight velocity of 50 km/s.
    This converts the orbital radius to about 0.06 pc; the paper notes the radius would be smaller with a larger transverse component.
  • domain assumption The ambient sound speed is 10 km/s and the black hole velocity is 30 km/s, giving a BHL capture radius of about 0.3 pc.
    Standard warm ISM values; the capture radius is used only as an order-of-magnitude comparison.
  • domain assumption Photoionization models with log U = -1.5, CLOUDY, and SMC-bar dust extinction describe the absorber and SED.
    Model choices in Methods 7 and 9; the absorber constraints do not include internal dust or emission contamination, as admitted in Methods 9.
  • domain assumption Bondi-Hoyle-Lyttleton accretion, in which a moving black hole captures gas from a gravitationally focused wake, is the correct description of gas capture.
    The theoretical framework from refs 6 and 7; its applicability to a clumpy, inhomogeneous ISM is assumed.

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Cite this review

Pith. "Pith review of A Wandering 35,000-Solar-Mass Black Hole Fed by a Gravitational Wake." pith.science (2026). https://pith.science/paper/ZNDWX2PF

@misc{pith2026260810719,
  author       = {Pith},
  title        = {Pith review of: A Wandering 35,000-Solar-Mass Black Hole Fed by a Gravitational Wake},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/ZNDWX2PF}},
  note         = {Machine review of arXiv:2608.10719}
}
read the original abstract

Intermediate-mass black holes are widely considered to be the seeds of supermassive black holes, a substantial population of which is expected to remain displaced from galactic nuclei owing to hierarchical galaxy assembly and inefficient dynamical friction. While several fueling channels can sustain central black holes, those pathways are largely inaccessible to off-nuclear black holes, leaving their fuel supply uncertain. As these wandering black holes move through the interstellar medium of their host galaxies, theory predicts that they can capture gas from the dense wake produced by gravitational focusing. However, direct observational evidence for this process has remained elusive. Here we report evidence for a wandering intermediate-mass black hole of 35,000 solar mass accreting through such a gravitational wake. Its black-hole nature is supported by broad-line emission, a compact continuum counterpart, long-term optical variability, and a power-law-like spectral energy distribution. Multi-epoch spectroscopy reveals three distinct gas components: a blueshifted, low-density upstream flow; a redshifted, dense downstream wake; and optically thick absorbers well within the capture radius that drive rapid changing-look variability in the broad-line emission. This discovery establishes a previously unobserved channel for the growth of wandering intermediate-mass black holes.

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Works this paper leans on

69 extracted references · 65 canonical work pages

  1. [1]

    Formation of supermassive black holes.Astronomy and Astrophysics Review18, 279–315 (2010)

    Volonteri, M. Formation of supermassive black holes.Astronomy and Astrophysics Review18, 279–315 (2010)

    work page 2010

  2. [2]

    E., Strader, J

    Greene, J. E., Strader, J. & Ho, L. C. Intermediate-Mass Black Holes.Annu. Rev. Astron. Astrophys.58, 257–312 (2020)

    work page 2020

  3. [3]

    M.et al.Multimessenger signatures of massive black holes in dwarf galaxies.Mon

    Bellovary, J. M.et al.Multimessenger signatures of massive black holes in dwarf galaxies.Mon. Not. R. Astron. Soc.482, 2913–2923 (2019)

    work page 2019

  4. [4]

    & Quinn, T

    Ricarte, A., Tremmel, M., Natarajan, P ., Zimmer, C. & Quinn, T. Origins and demographics of wandering black holes.Mon. Not. R. Astron. Soc.503, 6098–6111 (2021)

    work page 2021

  5. [5]

    S.et al.Population statistics of intermediate-mass black holes in dwarf galaxies using the NEWHORIZON simulation.Mon

    Beckmann, R. S.et al.Population statistics of intermediate-mass black holes in dwarf galaxies using the NEWHORIZON simulation.Mon. Not. R. Astron. Soc.523, 5610–5623 (2023)

    work page 2023

  6. [6]

    A review of Bondi-Hoyle-Lyttleton accretion.New Astronomy Reviews48, 843–859 (2004)

    Edgar, R. A review of Bondi-Hoyle-Lyttleton accretion.New Astronomy Reviews48, 843–859 (2004)

    work page 2004

  7. [7]

    & Y ajima, H

    Ogata, E., Ohsuga, K., Fukushima, H. & Y ajima, H. Three-dimensional radiation hydrodynamics simulations of wandering intermediate-mass black holes considering the anisotropic radiation and dust sublimation.Mon. Not. R. Astron. Soc.528, 2588–2599 (2024)

    work page 2024

  8. [8]

    D.et al.DDO 161 and UGCA 319: an isolated pair of nearby dwarf galaxies.Mon

    Karachentsev, I. D.et al.DDO 161 and UGCA 319: an isolated pair of nearby dwarf galaxies.Mon. Not. R. Astron. Soc.469, L113–L117 (2017)

    work page 2017

Show all 69 references
  1. [9]

    O.et al.Spitzer Local Volume Legacy (LVL) SEDs and physical properties.Mon

    Cook, D. O.et al.Spitzer Local Volume Legacy (LVL) SEDs and physical properties.Mon. Not. R. Astron. Soc. 445, 899–912 (2014)

    2014

  2. [10]

    de Blok, W. J. G.et al.MHONGOOSE: A MeerKAT nearby galaxy H I survey.Astron. Astrophys.688, A109 (2024)

    2024

  3. [11]

    Li, X.et al.Dwarf Galaxy Integral-field Survey (DGIS): Survey Overview and the Results of a Global Mass— Metallicity Relation.Astrophys. J. Supp.282, 16 (2026)

    2026

  4. [12]

    Too-many-satellites

    Li, J., Greene, J. E., Danieli, S., Carlsten, S. G. & Geha, M. A Possible “Too-many-satellites” Problem in the Isolated Dwarf Galaxy DDO 161.Astrophys. J. Let.998, L24 (2026)

    2026

  5. [13]

    B., Loubser, S

    Alabi, A. B., Loubser, S. I., Mogotsi, M. K. & Zabel, N. Stars and ionized gas in UGCA 320: a nearby gas-rich, dwarf irregular galaxy.Mon. Not. R. Astron. Soc.543, 3613–3627 (2025)

    2025

  6. [14]

    Zabel, N.et al.Tracing neutral hydrogen in UGCA 320: a MHONGOOSE perspective on an edge-on dwarf galaxy in a group environment.Mon. Not. R. Astron. Soc.548, stag604 (2026)

    2026

  7. [15]

    In McLean, I

    Bacon, R.et al.The MUSE second-generation VLT instrument. In McLean, I. S., Ramsay, S. K. & Takami, H. (eds.)Ground-based and Airborne Instrumentation for Astronomy III, vol. 7735 ofSociety of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 773508 (2010).2211.16795

    2010 arXiv

  8. [16]

    P ., Bautz, M

    Garmire, G. P ., Bautz, M. W., Ford, P . G., Nousek, J. A. & Ricker, G. R., Jr. Advanced ccd imaging spectrometer (acis) instrument on the chandra x-ray observatory.Proc. SPIE4851, 28–44 (2003)

    2003

  9. [17]

    van der Hucht, K. A. The VIIth catalogue of galactic Wolf-Rayet stars.New Astronomy Reviews45, 135–232 (2001)

    2001

  10. [18]

    Dopita, M.et al.The Wide Field Spectrograph (WiFeS): performance and data reduction.Astrophysics and Space Science327, 245–257 (2010)

    2010

  11. [19]

    Sirianni, M.et al.The Photometric Performance and Calibration of the Hubble Space Telescope Advanced Camera for Surveys.Publ. Astron. Soc. Pac.117, 1049–1112 (2005)

    2005

  12. [20]

    E., Greene, J

    Reines, A. E., Greene, J. E. & Geha, M. Dwarf Galaxies with Optical Signatures of Active Massive Black Holes. Astrophys. J.775, 116 (2013)

    2013

  13. [21]

    C., Kirshner, R

    Smith, R. C., Kirshner, R. P ., Blair, W. P . & Winkler, P . F . Six Balmer-dominated Supernova Remnants.Astrophys. J.375, 652 (1991)

    1991

  14. [22]

    Astrophys

    Li, C.-J.et al.Forbidden Line Emission from Type Ia Supernova Remnants Containing Balmer-dominated Shells. Astrophys. J.923, 141 (2021)

    2021

  15. [23]

    A., Phillips, M

    Baldwin, J. A., Phillips, M. M. & Terlevich, R. Classification parameters for the emission-line spectra of extragalactic objects.Publ. Astron. Soc. Pac.93, 5–19 (1981)

    1981

  16. [24]

    Inayoshi, K. & Ho, L. C. A Critical Evaluation of the Physical Nature of the Little Red Dots.arXiv e-prints arXiv:2512.03130 (2025)

    2025

  17. [25]

    Maiolino, R.et al.A black hole in a near pristine galaxy 700 Myr after the big bang.Mon. Not. R. Astron. Soc. 548, staf2109 (2026)

    2026

  18. [26]

    Ji, X.et al.Lord of LRDs: insights into a ’Little Red Dot’ with a low-ionization spectrum at z = 0.1.Mon. Not. R. Astron. Soc.545, staf2235 (2026)

    2026

  19. [27]

    Summary of the content and survey properties.Astron

    Gaia Collaborationet al.Gaia Data Release 3. Summary of the content and survey properties.Astron. Astrophys. 674, A1 (2023). 9

    2023

  20. [28]

    M., Weis, K., Davidson, K., Bomans, D

    Humphreys, R. M., Weis, K., Davidson, K., Bomans, D. J. & Burggraf, B. Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants.Astrophys. J.790, 48 (2014)

    2014

  21. [29]

    J.169, 128 (2025)

    Spejcher, B.et al.An Investigation into the Variability of Luminous Blue Variable Stars with TESS.Astron. J.169, 128 (2025)

    2025

  22. [30]

    M., Ganeshalingam, M

    Smith, N., Li, W., Silverman, J. M., Ganeshalingam, M. & Filippenko, A. V. Luminous blue variable eruptions and related transients: diversity of progenitors and outburst properties.Mon. Not. R. Astron. Soc.415, 773–810 (2011)

    2011

  23. [31]

    M., Gordon, M

    Humphreys, R. M., Gordon, M. S., Martin, J. C., Weis, K. & Hahn, D. Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, B[e] Supergiants, and the Warm Hypergiants: How to Tell Them Apart.Astrophys. J.836, 64 (2017)

    2017

  24. [32]

    M.et al.Luminous and Variable Stars in M31 and M33

    Humphreys, R. M.et al.Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-red Supergiant Evolution.Astrophys. J.773, 46 (2013)

    2013

  25. [33]

    & Maiolino, R

    Inayoshi, K. & Maiolino, R. Extremely Dense Gas around Little Red Dots and High-redshift Active Galactic Nuclei: A Nonstellar Origin of the Balmer Break and Absorption Features.Astrophys. J. Let.980, L27 (2025)

    2025

  26. [34]

    Ji, X.et al.BlackTHUNDER—A non-stellar Balmer break in a black hole-dominated little red dot at z = 7.04.Mon. Not. R. Astron. Soc.544, 3900–3935 (2025)

    2025

  27. [35]

    J.997, 364 (2026)

    Lin, X.et al.The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes.Astrophys. J.997, 364 (2026)

    2026

  28. [36]

    & Kimeswenger, S

    Proxauf, B., ¨Ottl, S. & Kimeswenger, S. Upgrading electron temperature and electron density diagnostic diagrams of forbidden line emission.Astron. Astrophys.561, A10 (2014)

    2014

  29. [37]

    A., Ferland, G

    Baldwin, J. A., Ferland, G. J., Korista, K. T., Hamann, F . & LaCluyz ´e, A. The Origin of Fe II Emission in Active Galactic Nuclei.Astrophys. J.615, 610–624 (2004)

    2004

  30. [38]

    L.et al.The CaFe Project: Optical Fe II and Near-infrared Ca II Triplet Emission in Active Galaxies

    Mart ´ınez-Aldama, M. L.et al.The CaFe Project: Optical Fe II and Near-infrared Ca II Triplet Emission in Active Galaxies. II. The Driver(s) of the Ca II and Fe II and Its Potential Use as a Chemical Clock.Astrophys. J.918, 29 (2021)

    2021

  31. [39]

    & Kawara, K

    Matsuoka, Y ., Oyabu, S., Tsuzuki, Y . & Kawara, K. Observations of O I and Ca II Emission Lines in Quasars: Implications for the Site of Fe II Line Emission.Astrophys. J.663, 781–798 (2007)

    2007

  32. [40]

    L.et al.O I and Ca II Observations in Intermediate Redshift Quasars.Astrophys

    Mart ´ınez-Aldama, M. L.et al.O I and Ca II Observations in Intermediate Redshift Quasars.Astrophys. J. Supp. 217, 3 (2015)

    2015

  33. [41]

    The ESO Reflex environment.Astron

    Freudling, W.et al.Automated data reduction workflows for astronomy. The ESO Reflex environment.Astron. Astrophys.559, A96 (2013)

    2013

  34. [42]

    C.et al.The Pan-STARRS1 Surveys.arXiv e-printsarXiv:1612.05560 (2016)

    Chambers, K. C.et al.The Pan-STARRS1 Surveys.arXiv e-printsarXiv:1612.05560 (2016)

    2016 arXiv

  35. [43]

    A., Clayton, G

    Cardelli, J. A., Clayton, G. C. & Mathis, J. S. The Relationship between Infrared, Optical, and Ultraviolet Extinction. Astrophys. J.345, 245 (1989)

    1989

  36. [44]

    A.et al.The Spitzer Local Volume Legacy: Survey Description and Infrared Photometry.Astrophys

    Dale, D. A.et al.The Spitzer Local Volume Legacy: Survey Description and Infrared Photometry.Astrophys. J. 703, 517–556 (2009)

    2009

  37. [45]

    J., Vogt, F

    Childress, M. J., Vogt, F . P . A., Nielsen, J. & Sharp, R. G. PyWiFeS: a rapid data reduction pipeline for the Wide Field Spectrograph (WiFeS).Astrophysics and Space Science349, 617–636 (2014)

    2014

  38. [46]

    A.et al.SkyMapper Southern Survey: Data release 4.Publ

    Onken, C. A.et al.SkyMapper Southern Survey: Data release 4.Publ. of the Astron. Soc. of Australia41, e061 (2024)

    2024

  39. [47]

    Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions

    Cappellari, M. Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions. Mon. Not. R. Astron. Soc.466, 798–811 (2017)

    2017

  40. [48]

    Mill ´an-Irigoyen, I.et al.HR-PYPOPSTAR: high-wavelength-resolution stellar populations evolutionary synthesis model.Mon. Not. R. Astron. Soc.506, 4781–4799 (2021)

    2021

  41. [49]

    D., Clayton, G

    Gordon, K. D., Clayton, G. C., Misselt, K. A., Landolt, A. U. & Wolff, M. J. A Quantitative Comparison of the Small Magellanic Cloud, Large Magellanic Cloud, and Milky Way Ultraviolet to Near-Infrared Extinction Curves. Astrophys. J.594, 279–293 (2003)

    2003

  42. [50]

    Beroiz, M., Cabral, J. B. & Sanchez, B. Astroalign: A Python module for astronomical image registration.Astron- omy and Computing32, 100384 (2020)

    2020

  43. [51]

    J.et al.The Zwicky Transient Facility: Data Processing, Products, and Archive.Publ

    Masci, F . J.et al.The Zwicky Transient Facility: Data Processing, Products, and Archive.Publ. Astron. Soc. Pac. 131, 018003 (2019)

    2019

  44. [52]

    Zwicky Transient Facility Image Service

    IRSA. Zwicky Transient Facility Image Service. NASA IPAC DataSet, IRSA539 (2022)

    2022

  45. [53]

    C.et al.The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission.Astrophys

    Martin, D. C.et al.The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission.Astrophys. J. Let.619, L1–L6 (2005)

    2005

  46. [54]

    Roming, P . W. A.et al.The Swift Ultra-Violet/Optical Telescope.Space Science Reviews120, 95–142 (2005). 10

    2005

  47. [55]

    A.et al.SkyMapper Southern Survey: Second data release (DR2).Publ

    Onken, C. A.et al.SkyMapper Southern Survey: Second data release (DR2).Publ. of the Astron. Soc. of Australia 36, e033 (2019)

    2019

  48. [56]

    & Madore, B

    Gil de Paz, A. & Madore, B. F . Palomar/Las Campanas Imaging Atlas of Blue Compact Dwarf Galaxies. II. Surface Photometry and the Properties of the Underlying Stellar Population.Astrophys. J. Supp.156, 345–360 (2005)

    2005

  49. [57]

    Gil de Paz, A.et al.The GALEX Ultraviolet Atlas of Nearby Galaxies.Astrophys. J. Supp.173, 185–255 (2007)

    2007

  50. [58]

    Juod ˇzbalis, I.et al.JADES - the Rosetta stone of JWST -discovered AGN: deciphering the intriguing nature of early AGN.Mon. Not. R. Astron. Soc.535, 853–873 (2024)

    2024

  51. [59]

    & Kurucz, R

    Castelli, F . & Kurucz, R. L. New Grids of ATLAS9 Model Atmospheres. In Piskunov, N., Weiss, W. W. & Gray, D. F . (eds.)Modelling of Stellar Atmospheres, vol. 210 ofIAU Symposium, A20 (2003).astro-ph/0405087

    2003 arXiv

  52. [60]

    Choi, J.et al.Mesa Isochrones and Stellar Tracks (MIST). I. Solar-scaled Models.Astrophys. J.823, 102 (2016)

    2016

  53. [61]

    Greco, J. P . & Danieli, S. ArtPop: A Stellar Population and Image Simulation Python Package.Astrophys. J.941, 26 (2022)

    2022

  54. [62]

    J.et al.The 2017 Release Cloudy.Rev

    Ferland, G. J.et al.The 2017 Release Cloudy.Rev. Mex. Astron. Astrofis.53, 385–438 (2017)

    2017

  55. [63]

    J., Dopita, M

    Kewley, L. J., Dopita, M. A., Sutherland, R. S., Heisler, C. A. & Trevena, J. Theoretical Modeling of Starburst Galaxies.Astrophys. J.556, 121–140 (2001)

    2001

  56. [64]

    Kauffmann, G.et al.The host galaxies of active galactic nuclei.Mon. Not. R. Astron. Soc.346, 1055–1077 (2003)

    2003

  57. [65]

    J., Groves, B., Kauffmann, G

    Kewley, L. J., Groves, B., Kauffmann, G. & Heckman, T. The host galaxies and classification of active galactic nuclei.Mon. Not. R. Astron. Soc.372, 961–976 (2006)

    2006

  58. [66]

    F ., Reines, A

    Baldassare, V. F ., Reines, A. E., Gallo, E. & Greene, J. E. X-ray and Ultraviolet Properties of AGNs in Nearby Dwarf Galaxies.Astrophys. J.836, 20 (2017)

    2017

  59. [67]

    Panessa, F .et al.On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies. Astron. Astrophys.455, 173–185 (2006). 11 METHODS 1 Multi-Epoch Spectroscopic Observations Spectroscopic observations were obtained with the Multi Unit Spectroscopic...

    2006

  60. [320]

    Fixed offset to sky (SLT)

    In this configuration, the spectra cover 4600 to 9350 ˚A, with a spectral resolution ofR∼1770 at 4800 ˚A andR∼2500 at 6500 ˚A. The final datacube was reconstructed with a spatial sampling of0.4 ′′ ×0.4 ′′ per spaxel. The point-spread function (PSF) of the final datacube was me...

    2016

  61. [2026]

    Assuming its orbital velocity is comparable to the observed line-of-sight velocity (∼50km s −1), the corresponding Keplerian radius for a black hole mass of3.5×10 4 M⊙ is∼0.06pc

    We can place an order-of-magnitude constraint on the location of the obscuring absorber. Assuming its orbital velocity is comparable to the observed line-of-sight velocity (∼50km s −1), the corresponding Keplerian radius for a black hole mass of3.5×10 4 M⊙ is∼0.06pc. This radi...

    2021

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.