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Scattered synchrotron emission and a giant torus revealed in polarized light in the nearest radio galaxy Centaurus A

T0 review · 3 major / 6 minor · reviewed 2026-08-08 · deepseek-v4-flash

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Pith's one-line read Spectropolarimetry of Centaurus A reveals a beamed jet seen in reflected, polarized light.

desk verdict New targeted spectropolarimetry of Cen A's knot delivers real surprises, but the key angle and polarization degree are small residuals after an uncertain ISP subtraction, so the sweeping interpretation outruns the evidence. read the letter →

arxiv 2502.05002 v1 pith:D7BJABJF submitted 2025-02-07 astro-ph.GA

F. Marin , D. Hutsemékers , C.-Z. Jiang , R. Antonucci , P. M. Ogle , A. Bagul , C. Ramos Almeida , M. Berton This is my paper · ORCID
classification astro-ph.GA
keywords CentaurusAspectropolarimetryhiddennarrow-lineregionAGNsynchrotronjetreflectiongiantcircumnucleartorusradiogalaxypolarizationmisdirectedBLLac
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

Using optical and near-infrared spectropolarimetry of a knot of polarized light 1.4 arcseconds (about 26 pc) from the hidden nucleus of Centaurus A, the paper finds that the knot's intrinsic polarization is 2–4% (decreasing from optical to near-infrared) with a position angle of 146°, perpendicular to the radio jet axis. It argues that this light is a beamed synchrotron jet seen in reflection: the jet's continuum and the narrow emission lines scatter off dust in the outermost narrow-line region after the innermost NLR is hidden by a giant (at least 10 pc) circumnuclear torus. No broad H-alpha line appears in polarized flux at 99% or higher confidence, so the scattered light does not come from a hidden broad-line region. If this reading is right, Cen A is the first clear case of reflected, beamed synchrotron emission, confirming long-standing predictions and defining a new class of hidden-NLR active galaxies that also includes NGC 4258 and 3C 270.

What carries the argument

The central mechanism is the hidden-NLR scattering geometry: a giant circumnuclear torus with vertical half-thickness 10.5–44.7 pc hides the bright inner narrow-line region, and the observed signal is light that escapes through the dust funnel and scatters once off dust in the outermost NLR. The key observable that carries the argument is the vector subtraction of interstellar polarization on the normalized Stokes $q$–$u$ plane: using a nearby pure-starlight region as the interstellar-polarization reference rotates the knot's polarization angle from roughly 115° (the dust-lane value) to 146°, exactly perpendicular to the radio jet. This subtraction is what exposes the intrinsic AGN component in both continuum and narrow lines.

What would settle it

Measure interstellar polarization toward several field stars in the same dust lane as the knot; if the reference-region polarization differs by more than about 0.5%, the derived intrinsic polarization and the 146° angle would shift and the scattering geometry would not be uniquely required. Alternatively, detecting a broad H-alpha line in a deeper polarized spectrum, or a big blue bump in ultraviolet nuclear spectra, would break the synchrotron-reflection interpretation.

Watch

Extended reading notes

Core claim

The authors claim that the continuum emission of Cen A's buried active nucleus is dominated by beamed synchrotron radiation, not by thermal accretion-disk emission, and that this radiation reaches us only after scattering off the exposed outer part of the narrow-line region. After subtracting the interstellar polarization measured in a nearby pure-starlight region, the scattered AGN light has 2–4% polarization whose angle is almost wavelength-independent and orthogonal to the jet position angle, while the narrow lines are polarized at 3–5% with the same perpendicular orientation. The absence of broad lines in the polarized spectrum rules out the usual type-2 hidden-BLR picture at 99% or higher probability. The authors therefore propose that a vertically extended torus (10–45 pc from the equatorial plane) obscures the base of the NLR, and that both the synchrotron continuum and the NLR line photons are polarized by a single scattering event in the NLR wind, producing the observed perpendicular polarization. They take this as confirmation of the prediction that beamed jet radiation can be seen in reflection.

Load-bearing premise

The whole decomposition rests on assuming that the polarization measured in the pure-starlight reference region is exactly the interstellar polarization along the line of sight to the polarized knot, so that a vector subtraction removes all dust-lane contamination.

Editorial extensions

If this is right

  • Cen A becomes the first confirmed case of a beamed synchrotron jet observed in reflected, polarized light, validating long-standing predictions that beamed jet radiation can be seen in reflection.
  • A new class of hidden-NLR active galaxies is defined, with NGC 4258 and 3C 270 as the other known members; such objects should show LINER-like spectra, no broad lines in polarized flux, and highly polarized narrow lines perpendicular to the jet.
  • The torus in Cen A must extend tens of parsecs vertically, implying a high covering factor and a larger obscuring structure than standard unification tori, consistent with the diffuse mid-infrared and roughly 110 pc-scale millimeter continuum already observed.
  • Surveys of misdirected BL Lac objects—low-power, non-thermal radio galaxies with jets near the line of sight—should be the hunting ground for additional hidden-NLR AGNs.
  • The non-detection of a broad H-alpha line at 99% or higher probability means the nucleus likely lacks a standard broad-line region, consistent with an advection-dominated accretion flow and a synchrotron-dominated continuum.

Reading between the lines

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

  • If the geometry is right, spatially resolved imaging polarimetry of the NLR on 10–100 pc scales should show a polarization angle pattern that rotates systematically with position relative to the jet axis; this is testable with current instrumentation and would distinguish single-scattering from multiple-scattering alternatives.
  • The interstellar-polarization correction is the fragile step: measuring interstellar polarization toward several independent stars in the dust lane near the knot would test whether the pure-starlight reference region is truly representative, since a spatial gradient in grain alignment would shift the intrinsic angle away from 146°.
  • Time-domain monitoring of the polarized knot could separate the synchrotron and scattering components: a beamed synchrotron flare should appear in the polarized continuum with a delay relative to the radio core, while the narrow-line polarization should remain stable.
  • The hidden-NLR class may be more common than recognized among low-luminosity FR I galaxies; applying the same spectropolarimetric analysis to other dust-lane-dominated cores could reveal more members.
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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

3 major / 6 minor

Summary. The paper presents VLT/FORS2 spectropolarimetry of the nuclear region of Centaurus A, targeting the compact polarized knot discovered by Schreier et al. (1996), a SE cloud, and an intermediate region M. The authors detect narrow AGN emission lines in the knot, find strong ISP-dominated polarization with P ≈ 15% at 6100 Å falling to ≈5% at 10000 Å, and after subtracting the region-M Stokes vector as an ISP template obtain an 'intrinsic' polarization of 2–4% with a position angle ≈146°, perpendicular to the jet PA of 55°. They report that the narrow lines are polarized at 3–5% with the same perpendicular angle, and that no broad Hα component is present in the polarized flux at ≥99% probability. They interpret the result as beamed synchrotron radiation from the jet scattered by the outer NLR, with a giant (≥10 pc) circumnuclear torus hiding the inner NLR, and propose a new class of 'hidden-NLR AGNs'.

Significance. If the ISP subtraction is robust, this is an important result: Cen A would be the first clear case of beamed BL Lac-like synchrotron emission observed in reflection, confirming a specific prediction of Blandford & Rees (1978) and Antonucci & Barvainis (1990), and it would establish a new observational class with two additional candidates (NGC 4258, 3C 270). The paper's strengths are its new high-quality FORS2 spectropolarimetric data with careful line identification, the quantitative no-broad-line constraint based on 2577 SDSS type-1 profiles, and the anchoring of the model to independent literature constraints (MIR diffuse emission, ALMA millimeter continuum, X-ray polarization, prior torus modeling). The weakness is that the central polarization-angle result is a small residual of two ~10% vectors, and the systematic uncertainty in the assumed ISP template is not quantified. This is a correctness-risk that can be addressed with additional analysis; the raw observational facts and the no-BLR constraint appear credible.

major comments (3)
  1. [Sect. 3.4, Eq. (5), Tables 2–3] The central observational claim — that the intrinsic polarization angle of the knot is 146°, perpendicular to the radio jet — rests on a small difference between two large measured Stokes vectors. After subtracting the region M q,u values from the knot values (Eq. 5), the residuals are q_int ~ 0.001–0.03 and u_int ~ -0.04 (Table 3), compared with observed q,u of about -0.077 and -0.096 (Table 2). The quoted uncertainties (0.6% in P, 4° in θ) are statistical only and do not include the systematic error in taking region M as the exact ISP toward the knot. Region M is a separate 1.5″-long aperture and is not cospatial with the knot; Schreier et al. (1996) showed that the dust-lane polarization varies on subarcsecond scales, and the paper itself shows that the SE cloud has a several-percent lower P at the same angle. A shift of only ~0.5–1% in q_ISP or u_ISP would drive q_int toward zero or negative and change the recovered angle by tens of degrees, destroying both the 2–4% P and the claimed orthogonality. The authors should either estimate and propagate this systematic uncertainty quantitatively (e.g., from the spatial gradient between M and the knot or from alternative ISP tracers) or demonstrate that the choice of region M is robust to such variations.
  2. [Sect. 3.4, Fig. 8, Table 3] The paper presents the 'intrinsic AGN polarization' as P = 2–4% while explicitly noting that the correction removes only ISP and not the host starlight contribution. Because the knot spectrum shows strong Ca ii triplet absorption (Fig. 5), starlight is a significant fraction of the total flux, and the quoted P is therefore only a lower limit on the true intrinsic polarization. The paper's line-versus-continuum comparison (Table 3: P ≈ 4–5% in lines versus 2–3% in adjacent continuum) could be biased if the starlight fraction differs between line and continuum bins. The authors should quantify the stellar dilution (e.g., via a stellar template fit) and report starlight-corrected values, or clearly state in the abstract and conclusions that the 2–4% figure is starlight-diluted.
  3. [Sect. 4.1, Fig. 9] The inferred vertical half-thickness of the torus, 10.5–44.7 pc, is derived by combining the projected distance between the radio core and the knot (0.6″–2.4″ from different references) with the assumption that the knot lies at the outer boundary of the torus and that the scattering occurs on the outermost NLR. This is a geometric model inference rather than a direct detection of a torus, and the factor-of-four range already indicates the sensitivity to the adopted core position. The title's phrase 'giant torus revealed' overstates the observational status; the torus is a plausible interpretation. The authors should soften this claim and explicitly list the model assumptions (e.g., that the scattered-light region is beyond the torus rim) in the abstract or conclusions.
minor comments (6)
  1. [Abstract and Sect. 1] The abstract uses 'by the mean of' where 'by means of' is intended, and the introduction contains 'Fanaro ff-Riley' with a missing space; please copyedit.
  2. [Eq. (4)] Equation (4) defines θ = 1/2 arctan(u/q); since q is negative in the observed data, the authors should state that the two-argument arctangent (atan2) is used to place θ in the correct quadrant.
  3. [Sects. 3.5 and 4.1] Two key comparisons rely on unpublished work: the 2577-profile sample and the 3C 270 spectropolarimetry are both cited as 'Jiang et al., in prep.'; for a journal submission these should be available (e.g., as arXiv preprints) or the claims should be rephrased as preliminary.
  4. [Fig. 8 caption] The caption states that the spectrum is 'corrected for the polluting contribution from the host starlight polarization estimated thanks to region M', but the correction made in Sect. 3.4 is for interstellar polarization, not starlight; the caption is misleading and should be reworded.
  5. [Table 2] Table 2 lists two identical groups of rows labelled '[S III]cb', '[S III]', and '[S III]cr'; if this is not a typo, the labels should distinguish the two measurements, and if it is a typo the duplicate rows should be removed.
  6. [Conclusion] The phrase 'beyond doubt' in the conclusion is stronger than the evidence warrants, given the systematic issues noted above; a more cautious formulation would be appropriate.

Circularity Check

0 steps flagged · score 2.0 of 10

No equation-level circularity: the key intrinsic angle and no-BLR limit are new measurements, not fitted inputs; the low score reflects minor in-preparation self-citations and a systematic-uncertainty concern in the ISP correction rather than a circular derivation.

full rationale

The derivation chain runs from the FORS2 spectropolarimetry (Sect. 2) to the detection of polarized narrow lines, the interstellar-polarization subtraction in Eq. (5), the resulting 146-degree intrinsic angle, and the hidden-NLR/synchrotron interpretation. None of these steps reduces a prediction to an input by construction: Eq. (5) is a standard vector subtraction using independently measured Stokes parameters from region M, and the intrinsic angle is a numerical consequence of those measurements rather than a fitted parameter. The no-BLR claim uses the SDSS type-1 sample of Jiang et al. (in prep.) as a sensitivity benchmark; although this is an in-preparation co-author paper, it does not assume the absence of a BLR in Cen A and is externally falsifiable, so it is not load-bearing circularity. The synchrotron and giant-torus model is anchored by external literature constraints (Bailey et al. 1986; Radomski et al. 2008; McCoy et al. 2017; Ehlert et al. 2022; Balmaverde et al. 2016). The principal vulnerability is observational rather than logical: the ISP correction assumes region M's polarization equals the ISP toward the knot, and because the intrinsic Stokes values are small residuals of two ~10% vectors, a spatial dust-polarization gradient could shift the recovered angle; this is a systematic-error concern, not a circular-derivation concern.

Assumptions & free parameters 1 free parameters · 6 assumptions · 1 invented entities

The central measurement rests on a small set of calibration and geometry assumptions. The strongest is the ISP template assumption, followed by unpolarized starlight, single-scattering optically thin NLR behavior, and the representativeness of the unpublished comparison sample. The model adds one geometric entity, a giant torus, with partial independent observational support.

free parameters (1)
  • P(lambda) power-law index k = -1.9 (knot), -2.1 (SE cloud), -2.2 (region M)
    Fitted to the observed polarization spectra to argue that region M and the SE cloud are ISP-dominated and comparable to the knot's reddening. These fits justify selecting region M as the ISP template in Sect. 3.4.
assumptions (6)
  • domain assumption Region M's polarization is purely interstellar (dichroic) and equal to the ISP toward the polarized knot.
    Invoked in Sect. 3.4, Eq. (5), for vector subtraction. Spatial variation of dust alignment or extinction between the apertures would bias the derived intrinsic angle and P.
  • domain assumption Host starlight is essentially unpolarized and only dilutes P, not theta.
    Used throughout the extraction of the AGN component in Sect. 3.4. If part of the stellar light is polarized, both the intrinsic P and theta would be biased.
  • domain assumption The NLR is optically thin, so narrow-line photons undergo single scattering while the continuum may already be polarized before scattering.
    This is the physical basis of the hidden-NLR model in Sect. 4.1, used to explain why line P exceeds continuum P and why the continuum polarization angle deviates by about 10 degrees.
  • domain assumption The jet position angle is 55 +/- 7 degrees, so the expected perpendicular polarization angle is near 145 degrees.
    Used to claim the intrinsic 146-degree angle is exactly perpendicular. The literature value carries its own uncertainty that is not propagated into the conclusion.
  • domain assumption The Balmaverde et al. (2016) result that the bright innermost NLR extends to about 10 pc in low-luminosity AGNs applies to Cen A.
    Used in Sect. 4.1 to argue that a torus half-height of 10.5-44.7 pc can hide the brightest NLR. This is an extrapolation from a sample of other objects to Cen A.
  • domain assumption The unpublished 2577-object SDSS sample is representative of type-1 AGN broad Halpha profiles for detection statistics.
    Used in Sect. 3.5 to derive the >=99% no-BLR probability. The sample is not publicly available and its selection criteria are only sketched.
invented entities (1)
  • Giant circumnuclear torus with vertical half-thickness 10.5-44.7 pc in Cen A independent evidence
    purpose: To obscure the innermost NLR and force scattered light to reach the observer only after scattering in the outer NLR, producing high polarization perpendicular to the radio jet.
    Not directly imaged. It is supported by prior JHK torus modeling (Bryant & Hunstead 1999), diffuse mid-infrared emission (Radomski et al. 2008), and ALMA millimeter continuum size (McCoy et al. 2017), but the exact height is inferred from projected source distances, not measured.

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Pith. "Pith review of Scattered synchrotron emission and a giant torus revealed in polarized light in the nearest radio galaxy Centaurus A." pith.science (2026). https://pith.science/paper/D7BJABJF

@misc{pith2026250205002,
  author       = {Pith},
  title        = {Pith review of: Scattered synchrotron emission and a giant torus revealed in polarized light in the nearest radio galaxy Centaurus A},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/D7BJABJF}},
  note         = {Machine review of arXiv:2502.05002}
}
read the original abstract

Centaurus A (Cen A) is the closest radio galaxy and a prime example of a low-luminosity active galactic nucleus (AGN), exhibiting complex emissions across the electromagnetic spectrum. The nature of its continuum emission, particularly the mechanisms powering it, has been a subject of considerable debate due to the fact that the AGN is deeply buried in dust. This study aims to elucidate the origin of the continuum emission in Cen A and determine the geometrical arrangement of matter in the nuclear region by the mean of optical and near-infrared spectropolarimetry. We obtained spectropolarimetric data of Cen A using the VLT/FORS2. The analysis revealed a region showing strong and narrow emission lines associated with AGN activity. After correction for interstellar polarization in the dust lane (but not for starlight), the intrinsic polarization of the scattered AGN light exhibits a polarization degree of 2-4%, decreasing from optical to near-infrared, associated with a polarization position angle perpendicular to the radio jet axis. We exclude the presence of hidden broad line in our polarized flux spectrum at more than 99% probability. Narrow emission lines are found to be strongly polarized and orthogonal to the jet position angle. We demonstrate that a beamed synchrotron jet, scattering onto the narrow line region (NLR) best fits all the observational properties reported in this paper and the literature. In this model, the base of the NLR is obscured by a giant circumnuclear region and can only become visible through perpendicular scattering onto the outermost part of the NLR, naturally producing high polarization degrees and polarization angles perpendicular to the radio structure. This study provides strong evidence that Cen A defines a new class of hidden-NLR AGNs and supports old predictions that beamed synchrotron jets can be observed in reflection.

Figures

Figures reproduced from arXiv: 2502.05002 by the authors.

Figure 1
Figure 1. Position and orientation of the MOS slit superimposed on [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. 2D spectrum (both ordinary and extraordinary rays) obtained by the VLT/ [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. R-band map of the central region of Cen A, in Analog to [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figures from the paper (6 more)
Figure 4
Figure 4. Figure 4: VLT/FORS2 spectropolarimetry of Centaurus A’s polarized knot. The total flux spectrum is shown in the top-left panel. The Stokes parameters Q and U (normalized by I) are shown on the middle-left and bottom-left panels, respectively. The polarized flux (that is the mult…
Figure 5
Figure 5. Figure 5: Tellurics (absorption), host starlight (absorption) and [PITH_FULL_IMAGE:figures/full_fig_p007_5.png]
Figure 6
Figure 6. Figure 6: Same as Fig [PITH_FULL_IMAGE:figures/full_fig_p008_6.png]
Figure 7
Figure 7. Figure 7: Same as Fig [PITH_FULL_IMAGE:figures/full_fig_p009_7.png]
Figure 8
Figure 8. Figure 8: Intrinsic AGN polarization (in black) retrieved from the polarized knot (in grey), corrected for the polluting contribution [PITH_FULL_IMAGE:figures/full_fig_p010_8.png]
Figure 9
Figure 9. Figure 9: Schematic view of a hidden-NLR AGN. The black dot at [PITH_FULL_IMAGE:figures/full_fig_p012_9.png]

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 2 Pith papers

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

  1. XRISM analysis of the complex Fe K$\alpha$ line in Centaurus A

    astro-ph.HE 2025-07 conditional novelty 7.0 of 10

    XRISM's precision X-ray detector shows the iron K-alpha line of Centaurus A is a narrow doublet plus a broad component, implying emitting gas spans roughly 0.001 to 10 parsecs.

  2. The central engine of low-luminosity radio galaxy 3C 270 (NGC 4261)

    astro-ph.GA 2024-12 conditional novelty 6.0 of 10

    Polarized-light spectra of 3C 270 show no hidden broad-line region or big blue bump, indicating a radiatively inefficient accretion flow in this low-luminosity radio galaxy.

Reference graph

Works this paper leans on

61 extracted references · 51 canonical work pages · cited by 2 Pith papers

  1. [1]

    M., Hough, J

    Alexander, D. M., Hough, J. H., Young, S., et al. 1999, MNRAS, 303, L17

    work page 1999

  2. [2]

    1993, ARA&A, 31, 473

    Antonucci, R. 1993, ARA&A, 31, 473

    1993

  3. [3]

    2012, Astronomical and Astrophysical Transactions, 27, 557

    Antonucci, R. 2012, Astronomical and Astrophysical Transactions, 27, 557

    2012

  4. [4]

    & Barvainis, R

    Antonucci, R. & Barvainis, R. 1990, ApJ, 363, L17

    work page 1990

  5. [5]

    Antonucci, R. R. J. & Miller, J. S. 1985, ApJ, 297, 621

    1985

  6. [6]

    B., Hough, J

    Bailey, J., Sparks, W. B., Hough, J. H., & Axon, D. J. 1986, Nature, 322, 150

    work page 1986

  7. [7]

    D., & Marconi, A

    Balmaverde, B., Capetti, A., Moisio, D., Baldi, R. D., & Marconi, A. 2016, A&A, 586, A48

    work page 2016

  8. [8]

    J., Tran, H

    Barth, A. J., Tran, H. D., Brotherton, M. S., et al. 1999, AJ, 118, 1609

    work page 1999

Show all 61 references
  1. [9]

    2019, MNRAS, 488, L1

    Bianchi, S., Antonucci, R., Capetti, A., et al. 2019, MNRAS, 488, L1

    2019

  2. [10]

    Blandford, R. D. & Rees, M. J. 1978, Phys. Scr, 17, 265

    1978

  3. [11]

    P., Ró˙ za´nska, A., et al

    Borkar, A., Adhikari, T. P., Ró˙ za´nska, A., et al. 2021, MNRAS, 500, 3536

    2021

  4. [12]

    A., Dunlop, J

    Bruce, V . A., Dunlop, J. S., Mortlock, A., et al. 2016, MNRAS, 458, 2391

    2016

  5. [13]

    Bryant, J. J. & Hunstead, R. W. 1999, MNRAS, 308, 431

    1999

  6. [14]

    O., Feigelson, E

    Burns, J. O., Feigelson, E. D., & Schreier, E. J. 1983, ApJ, 273, 128

    1983

  7. [15]

    J., Chiaberge, M., et al

    Capetti, A., Axon, D. J., Chiaberge, M., et al. 2007, A&A, 471, 137

    2007

  8. [16]

    2019, A&A, 623, A79

    Combes, F., García-Burillo, S., Audibert, A., et al. 2019, A&A, 623, A79

    2019

  9. [17]

    R., Ferrazzoli, R., Marinucci, A., et al

    Ehlert, S. R., Ferrazzoli, R., Marinucci, A., et al. 2022, ApJ, 935, 116

    2022

  10. [18]

    & Hall, J

    Elvius, A. & Hall, J. S. 1964, Lowell Observatory Bulletin, 6, 123

    1964

  11. [19]

    A., Kraft, R

    Evans, D. A., Kraft, R. P., Worrall, D. M., et al. 2004, ApJ, 612, 786 García-Burillo, S., Alonso-Herrero, A., Ramos Almeida, C., et al. 2021, A&A, 652, A98 García-Burillo, S., Combes, F., Ramos Almeida, C., et al. 2019, A&A, 632, A61 García-Burillo, S., Hicks, E. K. S., Alons...

    2004

  12. [20]

    Goodrich, R. W. & Miller, J. S. 1994, ApJ, 434, 82 H. E. S. S. Collaboration, Abdalla, H., Abramowski, A., et al. 2018, A&A, 619, A71

    1994

  13. [21]

    Harris, G. L. H., Rejkuba, M., & Harris, W. E. 2010, PASA, 27, 457 Hönig, S. F. & Beckert, T. 2007, MNRAS, 380, 1172

    2010

  14. [22]

    F., Hayward, C

    Hopkins, P. F., Hayward, C. C., Narayanan, D., & Hernquist, L. 2012, Monthly Notices of the Royal Astronomical Society, 420, 320

    2012

  15. [23]

    Hopkins, P. F. & Quataert, E. 2010, MNRAS, 407, 1529

    2010

  16. [24]

    H., Bailey, J

    Hough, J. H., Bailey, J. A., Rouse, M. F., & Whittet, D. C. B. 1987, MNRAS, 227, 1P

    1987

  17. [25]

    2024, PASJ[arXiv:2406.14488]

    Iwata, T., Tanimoto, A., Odaka, H., et al. 2024, PASJ[arXiv:2406.14488]

    2024 arXiv

  18. [26]

    2019, FORS Pipeline User Manual

    Izzo, C., de Bilbao, L., & Larsen, J. 2019, FORS Pipeline User Manual. VLT- MAN-ESO-19500-4106

    2019

  19. [27]

    C., Ferrarese, L., van den Bosch, F., & O’Connell, R

    Jaffe, W., Ford, H. C., Ferrarese, L., van den Bosch, F., & O’Connell, R. W. 1993, Nature, 364, 213

    1993

  20. [28]

    2021, Nature Astronomy, 5, 1017

    Janssen, M., Falcke, H., Kadler, M., et al. 2021, Nature Astronomy, 5, 1017

    2021

  21. [29]

    J., Ricci, C., Trakhtenbrot, B., et al

    Koss, M. J., Ricci, C., Trakhtenbrot, B., et al. 2022, ApJS, 261, 2

    2022

  22. [30]

    P., Forman, W., Jones, C., et al

    Kraft, R. P., Forman, W., Jones, C., et al. 2000, ApJ, 531, L9

    2000

  23. [31]

    Liu, B. F. & Taam, R. E. 2009, ApJ, 707, 233

    2009

  24. [32]

    J., et al

    Marconi, A., Capetti, A., Axon, D. J., et al. 2001, ApJ, 549, 915

    2001

  25. [33]

    R., et al

    Marin, F., Barnouin, T., Ehlert, S. R., et al. 2023, MNRAS, 526, 6321

    2023

  26. [34]

    S., et al

    McCoy, M., Ott, J., Meier, D. S., et al. 2017, ApJ, 851, 76

    2017

  27. [35]

    B., Kewley, L

    McPartland, C., Sanders, D. B., Kewley, L. J., & Leslie, S. K. 2019, MNRAS, 482, L129

    2019

  28. [36]

    Meisenheimer, K., Tristram, K. R. W., Jaffe, W., et al. 2007, A&A, 471, 453

    2007

  29. [37]

    1983, in Planetary Nebulae, ed

    Mendoza, C. 1983, in Planetary Nebulae, ed. L. H. Aller, V ol. 103, 143–172

    1983

  30. [38]

    Miller, J. S. & Goodrich, R. W. 1990, ApJ, 355, 456

    1990

  31. [39]

    1995, Nature, 373, 127

    Miyoshi, M., Moran, J., Herrnstein, J., et al. 1995, Nature, 373, 127

    1995

  32. [40]

    2022, MNRAS, 509, 2637

    Netzer, H. 2022, MNRAS, 509, 2637

    2022

  33. [41]

    M., Cohen, M

    Ogle, P. M., Cohen, M. H., Miller, J. S., et al. 1997, ApJ, 482, L37

    1997

  34. [42]

    2010, A&A, 519, A45

    Ojha, R., Kadler, M., Böck, M., et al. 2010, A&A, 519, A45

    2010

  35. [43]

    E., Shaw, R

    Osterbrock, D. E., Shaw, R. A., & Veilleux, S. 1990, ApJ, 352, 561

    1990

  36. [44]

    H., Young, S., et al

    Packham, C., Hough, J. H., Young, S., et al. 1996, MNRAS, 278, 406

    1996

  37. [45]

    & Algaba, J

    Park, J. & Algaba, J. C. 2022, Galaxies, 10, 102

    2022

  38. [46]

    S., Biretta, J

    Perlman, E. S., Biretta, J. A., Zhou, F., Sparks, W. B., & Macchetto, F. D. 1999, AJ, 117, 2185

    1999

  39. [47]

    Peterson, B. M. 1997, An Introduction to Active Galactic Nuclei (Cambridge University Press)

    1997

  40. [48]

    C., Bland-Hawthorn, J., Green, J

    Quillen, A. C., Bland-Hawthorn, J., Green, J. D., et al. 2008, MNRAS, 384, 1469

    2008

  41. [49]

    T., Packham, C., Levenson, N

    Radomski, J. T., Packham, C., Levenson, N. A., et al. 2008, ApJ, 681, 141 Ramos Almeida, C., Levenson, N. A., Rodríguez Espinosa, J. M., et al. 2009, ApJ, 702, 1127 Ramos Almeida, C., Martínez González, M. J., Asensio Ramos, A., et al. 2016, MNRAS, 461, 1387

    2008

  42. [50]

    Rieger, F. M. & Aharonian, F. A. 2009, A&A, 506, L41 Rodríguez-Ardila, A. & Fonseca-Faria, M. A. 2020, ApJ, 895, L9

    2009

  43. [51]

    J., Capetti, A., Macchetto, F., Sparks, W

    Schreier, E. J., Capetti, A., Macchetto, F., Sparks, W. B., & Ford, H. J. 1996, ApJ, 459, 535

    1996

  44. [52]

    H., Hines, D

    Shi, Y ., Rieke, G. H., Hines, D. C., et al. 2006, ApJ, 653, 127

    2006

  45. [53]

    & Meadows, V

    Simpson, C. & Meadows, V . 1998, ApJ, 505, L99

    1998

  46. [54]

    2015, A&A, 576, A77

    Smette, A., Sana, H., Noll, S., et al. 2015, A&A, 576, A77

    2015

  47. [55]

    Tran, H. D. 1995, ApJ, 440, 565

    1995

  48. [56]

    2021, ApJ, 922, 85 van Dokkum, P

    Tzanavaris, P., Yaqoob, T., LaMassa, S., Ptak, A., & Yukita, M. 2021, ApJ, 922, 85 van Dokkum, P. G. 2001, PASP, 113, 1420 van Dokkum, P. G., Bloom, J., & Tewes, M. 2012, L.A.Cosmic: Laplacian Cos- mic Ray Identification

    2021

  49. [57]

    & Antonucci, R

    Whysong, D. & Antonucci, R. 2004, ApJ, 602, 116

    2004

  50. [58]

    J., Schmidt, G

    Wilkes, B. J., Schmidt, G. D., Smith, P. S., Mathur, S., & McLeod, K. K. 1995, ApJ, 455, L13

    1995

  51. [59]

    J., Wills, D., Breger, M., Antonucci, R

    Wills, B. J., Wills, D., Breger, M., Antonucci, R. R. J., & Barvainis, R. 1992, ApJ, 398, 454

    1992

  52. [60]

    N., & Grosso, N

    Younes, G., Porquet, D., Sabra, B., Reeves, J. N., & Grosso, N. 2012, A&A, 539, A104

    2012

  53. [61]

    H., Axon, D

    Young, S., Hough, J. H., Axon, D. J., Bailey, J. A., & Ward, M. J. 1995, MNRAS, 272, 513 Article number, page 13 of ??

    1995

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