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arxiv: 2606.27675 · v1 · pith:RTV72QSKnew · submitted 2026-06-26 · 🌌 astro-ph.GA

OzSSy1: The Australian Southern Seyfert-1 Spectroscopic Atlas and Catalogue at z < 0.1

Neelesh Amrutha , Christian Wolf , Christopher A. Onken , Wei Jeat Hon , Samuel Lai , Rachel Webster This is my paper

Pith reviewed 2026-06-29 04:23 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords broad-line AGNsspectroscopic atlassouthern skySeyfert galaxiesemission-line fittingAGN cataloguelow-redshift AGNsspectral decomposition
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The pith

A new atlas assembles spectra and line fits for 887 southern broad-line AGNs at z below 0.1.

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

The paper constructs a spectroscopic atlas of 887 broad-line active galactic nuclei in the Southern sky at redshifts below 0.1, with declinations south of the equator and away from the Galactic plane. Observations come from the Wide Field Spectrograph on the ANU 2.3 m telescope at resolving power around 3000, with spectra extracted in a fixed 6.7 arcsec aperture and accompanied by continuum decompositions plus fits to Balmer, helium, and forbidden lines that include broad components. The sample is presented as a largely complete census intended to support demographic studies and variability work when paired with time-domain surveys, and all data products are released publicly.

Core claim

We present a spectroscopic atlas of 887 broad-line active galactic nuclei (AGNs) in the Southern sky, spanning redshifts z < 0.1, declinations δ < 0 deg and Galactic latitudes |b| > 10 deg. The sample aims at being a largely complete census of nearby broad-line AGN. The atlas is constructed from observations with R∼3000 using the integral-field Wide Field Spectrograph at the Australian National University 2.3 m telescope. Spectra are extracted in a 6.7 arcsec aperture and have a median signal-to-noise ratio of 13 and 23 per Angstrom in the blue and red arms, respectively. Each spectrum is accompanied by a spectral decomposition that models the AGN continuum and host galaxy, along with fits t

What carries the argument

The atlas of 887 objects with 6.7-arcsec aperture spectra, continuum-plus-host decompositions, and multi-line fits including broad components.

If this is right

  • The released spectra and fits enable direct statistical studies of emission-line properties across a large nearby AGN sample.
  • Combined with future time-domain data the atlas supports variability analyses for the same objects.
  • Public availability allows cross-matching with multi-wavelength surveys for demographic work.
  • The southern coverage complements existing northern samples for all-sky population studies.

Where Pith is reading between the lines

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

  • Cross-matching the catalogue against X-ray or infrared selections could quantify how many broad-line AGNs are missed by optical criteria.
  • The line fits could be re-used to derive black-hole mass estimates or Eddington ratios for the full sample in a uniform way.
  • If aperture effects prove small, the same extraction method could be applied to larger integral-field surveys for consistency.

Load-bearing premise

The sample selection function is complete enough, and the fixed aperture plus moderate-resolution spectra capture representative broad-line properties without major bias from host light or aperture mismatch.

What would settle it

A count of all previously catalogued broad-line AGNs in the same sky area, redshift range, and latitude cut that differs substantially from 887 after applying the same selection criteria.

Figures

Figures reproduced from arXiv: 2606.27675 by Christian Wolf, Christopher A. Onken, Neelesh Amrutha, Rachel Webster, Samuel Lai, Wei Jeat Hon.

Figure 1
Figure 1. Figure 1: Distribution of the 887 AGNs in the atlas on the sky: The sample covers the Southern hemisphere at Galactic latitudes |𝑏| ≥ 10°. ure 2; using K_m_ext from 2MASS XSC), and require Milliquas ob￾jects to additionally satisfy selection criteria similar to AllBRICQS. In particular, we require: Gaia 𝑅p ≤ 18, parallax_over_error < 5, (pmra/pmra_error) 2 + (pmdec/pmdec_error) 2 < 25 or pmra2 + pmdec2 < 0.04, BP/RP… view at source ↗
Figure 2
Figure 2. Figure 2: AGN sample. Left: 𝐾 magnitudes (K_m_ext column from 2MASS XSC) vs redshift. Dashed lines denote constant absolute magnitudes of 𝑀K: {−23, −24, −25, −26}. The solid line marks the heuristic 𝐾 < 13 + 3 log(𝑧/0.1) limit we use for the Milliquas selection. The source surveys of the AGNs are marked separately. Right: The AGN monochromatic luminosity of the continuum, 𝐿5100 (𝜆𝐿𝜆 at 𝜆5100Å), as a function of reds… view at source ↗
Figure 3
Figure 3. Figure 3: Example spatial extraction images for six objects, ordered by redshift from top to bottom. The left column shows sources with high host-galaxy contribution, while the right column shows AGN-dominated systems. For each object, the WiFeS data cube is collapsed into median images in the blue and red arms, with flux units of erg s−1 cm−2 Å −1 . The solid circle indicates the 6.7 arcsec extraction aperture, and… view at source ↗
Figure 5
Figure 5. Figure 5: Distribution of differences in magnitudes extracted from the 6.7 arcsec aperture WiFeS spectra, with 6.0 arcsec magnitudes from SMSS DR4 in 𝑔, 𝑟 and 𝑖 bands. The dashed lines indicate medians of the differences. The dotted lines indicate the medians of the differences for 8.0 arcsec SMSS pho￾tometry. The solid lines indicate a linear interpolation to 6.7 arcsec aperture magnitudes. is therefore modelled us… view at source ↗
Figure 6
Figure 6. Figure 6: Spectrum decomposition: Examples with diverse H𝛽Br/[O iii] ratios and Balmer line SNRs, representative of average AGNs in the sample. Vertical dashed lines denote centroids of emission lines based on [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: SNR distribution of the fitted broad Balmer lines. The SNRs are computed by dividing the peak of the summed Gaussian components by the mean noise level in the fitted region. measured lag ratio 𝜏H𝛼/𝜏H𝛽 = 1.54 implies an expected line-width ratio of FWHMH𝛽/FWHMH𝛼 ∼ 1.24, in excellent agreement with our observations. A similar comparison between broad H𝛾 and H𝛽 is less robust. We measure a median FWHMH𝛾/FWHMH… view at source ↗
Figure 8
Figure 8. Figure 8: Comparison of the Balmer line luminosity for H𝛼, H𝛽 and H𝛾. The solid and dashed lines show the 1:1 relation and Case-B scenario respectively. Different SNR regimes are marked separately. For SNR > 3, both lines need to fulfil the condition, but for 2 < SNR < 3, one of the lines may have SNR > 3. 3.2 3.4 3.6 3.8 4.0 log FWHM(Hα) (km s−1 ) 3.2 3.4 3.6 3.8 4.0 log FWHM(H β) (km s −1 ) 2 < SNR < 3 SNR > 3 1:1… view at source ↗
Figure 9
Figure 9. Figure 9: Comparison of the Balmer line FWHM for H𝛼, H𝛽 and H𝛾 (see [PITH_FULL_IMAGE:figures/full_fig_p012_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: AGN classification decision tree. The full procedure is described in Section 5.5. The end nodes of the tree denote classification labels presented in the type column of the catalogue. 41 objects with bad spectrum quality are labelled "Bad" and are not assigned a type. 6.1 Ionisation diagnostics We present the standard BPT diagnostic diagrams in [PITH_FULL_IMAGE:figures/full_fig_p014_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: BPT diagram showing narrow line ratios log [O iii] 𝜆5008/H𝛽 versus log [N ii] 𝜆6585/H𝛼, log [S ii]𝜆𝜆6732, 6718/H𝛼, and log [O iii] 𝜆6300/H𝛼. The dashed curves in the [N ii] panel indicate the demarcation lines from Kewley et al. (2001) and Kauffmann et al. (2003) separating star forming and AGN regions. The regions between the curves are typically classified as composite galaxies. The remaining panels onl… view at source ↗
Figure 12
Figure 12. Figure 12: Balmer decrement 𝐿H𝛽/𝐿H𝛼 as a function of the H𝛽Br/[O iii] ratio. The running median is shown, with error bars indicating the 16th–84th percentile range. The horizontal line marks the Case B recombination value. The SNR regimes are marked separately, following from [PITH_FULL_IMAGE:figures/full_fig_p015_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: Equivalent width of broad H𝛽 and narrow [O iii], along with the H𝛽Br/[O iii] luminosity ratio as a function of AGN continuum luminosity, 𝐿5100. Running medians are shown, with error bars indicating the 16th–84th percentile range. A Baldwin effect is evident for narrow [O iii], while the trend is absent for broad H𝛽. the challenges in reliably separating AGN and host galaxy continua. Care must therefore be… view at source ↗
Figure 14
Figure 14. Figure 14: AGN power-law spectral index (in frequency space) as a function of (left) continuum luminosity, 𝐿5100, and (right) the AGN fraction of the total continuum. The horizontal line marks the theoretical expectation for a standard thin accretion disc (𝛼𝜈 = 1/3). A comparison with the SDSS quasar sample from Rakshit et al. (2020) is also presented. Objects with only AGN contribution no detected host components f… view at source ↗
Figure 15
Figure 15. Figure 15: Example transient follow-up use case for MCG−06−30−015. Top: WiFeS spectra obtained before, during, and after the event. The spectra are offset by 200 flux units for visual clarity. The spectrum obtained at MJD 60770 exhibits transient spectral features associated with the flare, while the spectrum obtained four weeks later has largely returned to the pre-flare state. Bottom: ATLAS 𝑜-band difference-flux … view at source ↗
read the original abstract

We present a spectroscopic atlas of 887 broad-line active galactic nuclei (AGNs) in the Southern sky, spanning redshifts $z < 0.1$, declinations $\delta < 0$ deg and Galactic latitudes $|b| > 10$ deg. The sample aims at being a largely complete census of nearby broad-line AGN. The atlas is constructed from observations with $R\sim3000$ using the integral-field Wide Field Spectrograph at the Australian National University 2.3 m telescope. Spectra are extracted in a 6.7 arcsec aperture and have a median signal-to-noise ratio of 13 and 23 per Angstrom in the blue and red arms, respectively. Each spectrum is accompanied by a spectral decomposition that models the AGN continuum and host galaxy, along with fits to the emission lines H$\gamma$, H$\beta$, H$\alpha$, He II, He I, [O III], [O I], [N II] and [S II], including broad Balmer and Helium components. The data products are publicly available and designed to support studies of population demographics and AGN variability in conjunction with future time-domain surveys.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript presents OzSSy1, a spectroscopic atlas and catalogue of 887 broad-line AGNs in the Southern sky (z < 0.1, δ < 0°, |b| > 10°). Data were obtained with the WiFeS integral-field spectrograph (R ~ 3000) on the ANU 2.3 m telescope; spectra are extracted through a fixed 6.7 arcsec aperture, have median S/N of 13 (blue) and 23 (red) per Å, and are accompanied by AGN+host continuum decompositions plus Gaussian fits to Hγ, Hβ, Hα, He II, He I, [O III], [O I], [N II] and [S II] (including broad components). The data products are released publicly to support demographic and variability studies with future time-domain surveys.

Significance. If the sample selection can be shown to be largely complete, the public release of 887 uniformly reduced and modeled spectra would constitute a useful resource for statistical studies of nearby broad-line AGN populations and for cross-matching with time-domain surveys. The provision of both raw and decomposed spectra plus the integral-field origin are practical strengths for community use.

major comments (2)
  1. [Abstract] Abstract: The headline framing that the sample 'aims at being a largely complete census of nearby broad-line AGN' is load-bearing for the paper's motivation and utility claims, yet no parent catalog, magnitude or emission-line pre-selection criteria, or completeness estimate is supplied. Without these, the 'largely complete' qualifier cannot be evaluated against independent number densities or other surveys.
  2. [Abstract] The manuscript provides no quantitative assessment of how the fixed 6.7 arcsec aperture extraction affects broad-line measurements (e.g., host contamination for low-luminosity objects or aperture losses), which directly impacts the reliability of the emission-line catalog for demographic studies.
minor comments (2)
  1. The median S/N values are stated but no distribution, wavelength dependence, or definition of the S/N measurement (e.g., per pixel vs. per resolution element) is given.
  2. No information is provided on how redshifts were measured or on any quality flags for the line fits (e.g., χ², parameter uncertainties).

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments, which highlight important areas for clarifying the sample selection and data characterization. We address each major comment below and will make revisions to improve the manuscript.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The headline framing that the sample 'aims at being a largely complete census of nearby broad-line AGN' is load-bearing for the paper's motivation and utility claims, yet no parent catalog, magnitude or emission-line pre-selection criteria, or completeness estimate is supplied. Without these, the 'largely complete' qualifier cannot be evaluated against independent number densities or other surveys.

    Authors: We agree that the abstract claim requires explicit supporting details to be defensible. The current manuscript does not supply a parent catalog, magnitude or emission-line pre-selection criteria, or a completeness estimate. We will add a new subsection in the methods section that describes the sample construction, including the parent catalogs, selection criteria, and a quantitative completeness assessment via comparison to independent AGN number densities from other surveys. We will also revise the abstract wording to align with the added details. revision: yes

  2. Referee: [Abstract] The manuscript provides no quantitative assessment of how the fixed 6.7 arcsec aperture extraction affects broad-line measurements (e.g., host contamination for low-luminosity objects or aperture losses), which directly impacts the reliability of the emission-line catalog for demographic studies.

    Authors: We acknowledge that the manuscript lacks a quantitative assessment of aperture effects on the broad-line measurements. We will add this analysis to the revised manuscript, including estimates of host contamination for low-luminosity objects and aperture losses, using the integral-field data properties and any available comparisons or simulations. revision: yes

Circularity Check

0 steps flagged

No circularity: pure observational data release with no derivations or fitted predictions

full rationale

The paper is an observational catalog presenting spectra, decompositions, and line fits for 887 AGNs selected by redshift, declination, and latitude cuts. No equations, models, or predictions are derived that reduce to inputs by construction; there are no self-definitional steps, fitted parameters renamed as predictions, or load-bearing self-citations. The 'largely complete census' phrasing is an unquantified selection assertion, not a mathematical result. The work is self-contained as a data product release.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

This is an observational data-release paper containing no mathematical derivations, free parameters, axioms, or invented entities.

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Reference graph

Works this paper leans on

224 extracted references · 219 canonical work pages · 106 internal anchors

  1. [1]

    Slow blue nuclear hypervariables in PanSTARRS-1

    Slow-blue nuclear hypervariables in PanSTARRS-1. , keywords =. doi:10.1093/mnras/stw1963 , archivePrefix =. 1605.07842 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stw1963

  2. [2]

    The NumPy array: a structure for efficient numerical computation

    The NumPy Array: A Structure for Efficient Numerical Computation. Computing in Science and Engineering , keywords =. doi:10.1109/MCSE.2011.37 , archivePrefix =. 1102.1523 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1109/mcse.2011.37 2011

  3. [3]

    Computing in Science and Engineering , keywords =

    Matplotlib: A 2D Graphics Environment. Computing in Science and Engineering , keywords =. doi:10.1109/MCSE.2007.55 , adsurl =

    work page doi:10.1109/mcse.2007.55 2007

  4. [4]

    P., Belloni, T

    The 6dF Galaxy Survey: samples, observational techniques and the first data release. , keywords =. doi:10.1111/j.1365-2966.2004.08353.x , archivePrefix =. astro-ph/0403501 , primaryClass =

    work page doi:10.1111/j.1365-2966.2004.08353.x 2004

  5. [5]

    E., & Quataert, E

    The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures. , keywords =. doi:10.1111/j.1365-2966.2009.15338.x , archivePrefix =. 0903.5451 , primaryClass =

    work page doi:10.1111/j.1365-2966.2009.15338.x 2009

  6. [6]

    L., Denneau, L., Heinze, A

    ATLAS: A High-cadence All-sky Survey System. , keywords =. doi:10.1088/1538-3873/aabadf , archivePrefix =. 1802.00879 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/1538-3873/aabadf

  7. [7]

    SkyMapper Southern Survey: First Data Release (DR1)

    SkyMapper Southern Survey: First Data Release (DR1). , keywords =. doi:10.1017/pasa.2018.5 , archivePrefix =. 1801.07834 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1017/pasa.2018.5 2018

  8. [8]

    , keywords =

    Unified models for active galactic nuclei and quasars. , keywords =. doi:10.1146/annurev.aa.31.090193.002353 , adsurl =

    work page doi:10.1146/annurev.aa.31.090193.002353

  9. [9]

    Unified Schemes for Radio-Loud Active Galactic Nuclei

    Unified Schemes for Radio-Loud Active Galactic Nuclei. , keywords =. doi:10.1086/133630 , archivePrefix =. astro-ph/9506063 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/133630

  10. [10]

    , keywords =

    Broad-line active galactic nuclei in the 6dF Galaxy Survey. , keywords =. doi:10.1093/mnras/stae2815 , archivePrefix =. 2410.08536 , primaryClass =

    work page doi:10.1093/mnras/stae2815

  11. [11]

    , keywords =

    The Wide Field Spectrograph (WiFeS). , keywords =. doi:10.1007/s10509-007-9510-z , archivePrefix =. 0705.0287 , primaryClass =

    work page doi:10.1007/s10509-007-9510-z

  12. [12]

    The Wide Field Spectrograph (WiFeS): Performance and Data Reduction

    The Wide Field Spectrograph (WiFeS): performance and data reduction. , keywords =. doi:10.1007/s10509-010-0335-9 , archivePrefix =. 1002.4472 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1007/s10509-010-0335-9

  13. [13]

    PyWiFeS: A Rapid Data Reduction Pipeline for the Wide Field Spectrograph (WiFeS)

    PyWiFeS: a rapid data reduction pipeline for the Wide Field Spectrograph (WiFeS). , keywords =. doi:10.1007/s10509-013-1682-0 , archivePrefix =. 1311.2666 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1007/s10509-013-1682-0

  14. [14]

    Newly discovered changing-look AGN

    SkyMapper colours of Seyfert galaxies and changing-look AGN - II. Newly discovered changing-look AGN. , keywords =. doi:10.1093/mnras/stab3694 , adsurl =

    work page doi:10.1093/mnras/stab3694

  15. [15]

    Nature Astronomy , keywords =

    Changing-look active galactic nuclei. Nature Astronomy , keywords =. doi:10.1038/s41550-023-02108-4 , archivePrefix =. 2211.05132 , primaryClass =

    work page doi:10.1038/s41550-023-02108-4

  16. [16]

    BAT AGN Spectroscopic Survey. I. Spectral Measurements, Derived Quantities, and AGN Demographics. , keywords =. doi:10.3847/1538-4357/aa8ec9 , archivePrefix =. 1707.08123 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aa8ec9

  17. [17]

    BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog. , keywords =. doi:10.3847/1538-4365/aa96ad , archivePrefix =. 1709.03989 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4365/aa96ad

  18. [18]

    , year = 1976, month = dec, volume =

    Variation of the spectrum of the Seyfert galaxy NGC 7603. , year = 1976, month = dec, volume =. doi:10.1086/182317 , adsurl =

    work page doi:10.1086/182317 1976

  19. [19]

    J., Prieto, J

    The Man behind the Curtain: X-Rays Drive the UV through NIR Variability in the 2013 Active Galactic Nucleus Outburst in NGC 2617. , keywords =. doi:10.1088/0004-637X/788/1/48 , archivePrefix =. 1310.2241 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/788/1/48 2013

  20. [20]

    AGN Type-casting: Mrk 590 No Longer Fits the Role

    The Typecasting of Active Galactic Nuclei: Mrk 590 no Longer Fits the Role. , keywords =. doi:10.1088/0004-637X/796/2/134 , archivePrefix =. 1404.4879 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/796/2/134

  21. [21]

    Changing-Look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars

    Changing-look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars. , keywords =. doi:10.3847/1538-4357/ab05e2 , archivePrefix =. 1810.00087 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/ab05e2

  22. [22]

    A Systematic Search for Changing-Look Quasars in SDSS

    A systematic search for changing-look quasars in SDSS. , keywords =. doi:10.1093/mnras/stv2997 , archivePrefix =. 1509.08393 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stv2997

  23. [23]

    , keywords =

    SkyMapper colours of Seyfert galaxies and Changing-Look AGN. , keywords =. doi:10.1093/mnras/staa2794 , archivePrefix =. 2009.04688 , primaryClass =

    work page doi:10.1093/mnras/staa2794 2009

  24. [24]

    , keywords =

    The Time Domain Spectroscopic Survey: Changing-look Quasar Candidates from Multi-epoch Spectroscopy in SDSS-IV. , keywords =. doi:10.3847/1538-4357/ac743f , archivePrefix =. 2201.09123 , primaryClass =

    work page doi:10.3847/1538-4357/ac743f

  25. [25]

    The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN

    The Discovery of the First Changing Look Quasar: New Insights Into the Physics and Phenomenology of Active Galactic Nucleus. , keywords =. doi:10.1088/0004-637X/800/2/144 , archivePrefix =. 1412.2136 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/800/2/144

  26. [26]

    Discovery of 21 New Changing-look AGNs in Northern Sky

    Discovery of 21 New Changing-look AGNs in the Northern Sky. , keywords =. doi:10.3847/1538-4357/aaca3a , archivePrefix =. 1711.08122 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aaca3a

  27. [27]

    Changing-state quasars

    Understanding extreme quasar optical variability with CRTS - II. Changing-state quasars. , keywords =. doi:10.1093/mnras/stz3244 , archivePrefix =. 1905.02262 , primaryClass =

    work page doi:10.1093/mnras/stz3244 1905

  28. [28]

    , keywords =

    BASS XXXIX: Swift-BAT AGN with changing-look optical spectra. , keywords =. doi:10.1093/mnras/stac3279 , archivePrefix =. 2211.04478 , primaryClass =

    work page doi:10.1093/mnras/stac3279

  29. [29]

    , keywords =

    A Transient ``Changing-look'' Active Galactic Nucleus Resolved on Month Timescales from First-year Sloan Digital Sky Survey V Data. , keywords =. doi:10.3847/2041-8213/ac9a47 , archivePrefix =. 2210.07258 , primaryClass =

    work page doi:10.3847/2041-8213/ac9a47 2041

  30. [30]

    Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. I. Sample from the Early Data. , keywords =. doi:10.3847/1538-4365/ad118a , archivePrefix =. 2307.08289 , primaryClass =

    work page doi:10.3847/1538-4365/ad118a

  31. [31]

    Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. II. Statistical Properties from the First Data Release. arXiv e-prints , keywords =. doi:10.48550/arXiv.2408.00402 , archivePrefix =. 2408.00402 , primaryClass =

    work page doi:10.48550/arxiv.2408.00402

  32. [32]

    , keywords =

    Confirming new changing-look AGNs discovered through optical variability using a random forest-based light-curve classifier. , keywords =. doi:10.1093/mnrasl/slac033 , archivePrefix =. 2203.15040 , primaryClass =

    work page doi:10.1093/mnrasl/slac033

  33. [33]

    Polarization of the changing-look quasar J1011+5442

    Polarization of the changing-look quasar J1011+5442. , keywords =. doi:10.1051/0004-6361/201731397 , archivePrefix =. 1707.05540 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1051/0004-6361/201731397

  34. [34]

    Mid-infrared variability of changing-look AGN

    Mid-infrared Variability of Changing-look AGNs. , keywords =. doi:10.3847/2041-8213/aa85de , archivePrefix =. 1707.02686 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/2041-8213/aa85de 2041

  35. [35]

    , keywords =

    Seyfert galaxies with weak broad H alpha emission lines. , keywords =. doi:10.1086/159306 , adsurl =

    work page doi:10.1086/159306

  36. [36]

    Spectroscopy

    Variability studies of Seyfert galaxies - II. Spectroscopy. , keywords =. doi:10.1093/mnras/257.4.677 , adsurl =

    work page doi:10.1093/mnras/257.4.677

  37. [37]

    SpectRes: A Fast Spectral Resampling Tool in Python

    SpectRes: A Fast Spectral Resampling Tool in Python. arXiv e-prints , keywords =. doi:10.48550/arXiv.1705.05165 , archivePrefix =. 1705.05165 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.1705.05165

  38. [38]

    , keywords =

    Bayesian AGN Decomposition Analysis for SDSS spectra: a correlation analysis of [O III] 5007 outflow kinematics with AGN and host galaxy properties. , keywords =. doi:10.1093/mnras/staa3278 , archivePrefix =. 2010.09748 , primaryClass =

    work page doi:10.1093/mnras/staa3278 2010

  39. [39]

    Evidence for Large Temperature Fluctuations in Quasar Accretion Disks From Spectral Variability

    Evidence for Large Temperature Fluctuations in Quasar Accretion Disks from Spectral Variability. , keywords =. doi:10.1088/0004-637X/783/2/105 , archivePrefix =. 1401.1211 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-637x/783/2/105

  40. [40]

    The Ensemble Photometric Variability of ~25000 Quasars in the Sloan Digital Sky Survey

    The Ensemble Photometric Variability of -0.5ex 25,000 Quasars in the Sloan Digital Sky Survey. , keywords =. doi:10.1086/380563 , archivePrefix =. astro-ph/0310336 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/380563

  41. [41]

    J., Almaini, O., Edge, A

    On the variability of quasars: a link between the Eddington ratio and optical variability?. , keywords =. doi:10.1111/j.1365-2966.2007.12655.x , archivePrefix =. 0711.4844 , primaryClass =

    work page doi:10.1111/j.1365-2966.2007.12655.x 2007

  42. [42]

    Extreme AGN variability: evidence of magnetically elevated accretion?

    Extreme AGN variability: evidence of magnetically elevated accretion?. , keywords =. doi:10.1093/mnrasl/sly213 , archivePrefix =. 1807.03314 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnrasl/sly213

  43. [43]

    1999, MNRAS, 309, 447, doi: 10.1046/j.1365-8711.1999.02853.x

    Long-term optical variability properties of the Palomar-Green quasars. , keywords =. doi:10.1046/j.1365-8711.1999.02556.x , archivePrefix =. astro-ph/9902254 , primaryClass =

    work page doi:10.1046/j.1365-8711.1999.02556.x 1999

  44. [44]

    Observational appearance

    Black holes in binary systems. Observational appearance. , year = 1973, month = jan, volume =

    1973

  45. [45]

    Hidden Broad Line Seyfert 2 Galaxies in the CfA and 12micron Samples

    Hidden Broad-Line Seyfert 2 Galaxies in the CFA and 12 M Samples. , keywords =. doi:10.1086/320926 , archivePrefix =. astro-ph/0105462 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/320926

  46. [46]

    The Unified Model & Evolution of Active Galaxies: Implications from a Spectropolarimetric Study

    The Unified Model and Evolution of Active Galaxies: Implications from a Spectropolarimetric Study. , keywords =. doi:10.1086/345473 , archivePrefix =. astro-ph/0210262 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/345473

  47. [47]

    M., Tremonti, C., et al.\ 2003, , 346, 1055, doi:10.1111/j.1365-2966.2003.07154.x

    The host galaxies of active galactic nuclei. , keywords =. doi:10.1111/j.1365-2966.2003.07154.x , archivePrefix =. astro-ph/0304239 , primaryClass =

    work page doi:10.1111/j.1365-2966.2003.07154.x 2003

  48. [48]

    Space density of optically-selected type 2 quasars

    Space Density of Optically Selected Type 2 Quasars. , keywords =. doi:10.1088/0004-6256/136/6/2373 , archivePrefix =. 0801.1115 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0004-6256/136/6/2373

  49. [49]

    Broad Hbeta Emission-Line Variability in a Sample of 102 Local Active Galaxies

    Broad H Emission-line Variability in a Sample of 102 Local Active Galaxies. , keywords =. doi:10.3847/0004-637X/821/1/33 , archivePrefix =. 1603.00035 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/0004-637x/821/1/33

  50. [50]

    , keywords =

    The Destruction and Recreation of the X-Ray Corona in a Changing-look Active Galactic Nucleus. , keywords =. doi:10.3847/2041-8213/ab91a1 , archivePrefix =. 2007.07275 , primaryClass =

    work page doi:10.3847/2041-8213/ab91a1 2041

  51. [51]

    A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes

    A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes. , keywords =. doi:10.1093/mnras/stv1095 , archivePrefix =. 1503.04870 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stv1095

  52. [52]

    Now You See It, Now You Don't: The Disappearing Central Engine of the Quasar J1011+5442

    Now you see it, now you don't: the disappearing central engine of the quasar J1011+5442. , keywords =. doi:10.1093/mnras/stv2385 , archivePrefix =. 1509.03640 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stv2385

  53. [53]

    On the Bardeen-Petterson Effect in black hole accretion discs

    On the Bardeen-Petterson effect in black hole accretion discs. , keywords =. doi:10.1093/mnras/stv014 , archivePrefix =. 1501.01687 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stv014

  54. [54]

    , keywords =

    Nozzle Shocks, Disk Tearing, and Streamers Drive Rapid Accretion in 3D GRMHD Simulations of Warped Thin Disks. , keywords =. doi:10.3847/1538-4357/ace051 , archivePrefix =. 2210.10053 , primaryClass =

    work page doi:10.3847/1538-4357/ace051

  55. [55]

    SDSS-V: Pioneering Panoptic Spectroscopy

    SDSS-V: Pioneering Panoptic Spectroscopy. arXiv e-prints , keywords =. doi:10.48550/arXiv.1711.03234 , archivePrefix =. 1711.03234 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.48550/arxiv.1711.03234

  56. [56]

    LSST: from Science Drivers to Reference Design and Anticipated Data Products

    LSST: From Science Drivers to Reference Design and Anticipated Data Products. , keywords =. doi:10.3847/1538-4357/ab042c , archivePrefix =. 0805.2366 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/ab042c

  57. [57]

    Insights from the VVDS and VIPERS surveys

    The Type II AGN-host galaxy connection. Insights from the VVDS and VIPERS surveys. , keywords =. doi:10.1051/0004-6361/202141072 , archivePrefix =. 2111.08730 , primaryClass =

    work page doi:10.1051/0004-6361/202141072

  58. [58]

    The incidence of obscuration in active galactic nuclei

    The incidence of obscuration in active galactic nuclei. , keywords =. doi:10.1093/mnras/stt2149 , archivePrefix =. 1311.1305 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stt2149

  59. [59]

    J., & Zanotti, O

    Changing look: from Compton-thick to Compton-thin, or the rebirth of fossil active galactic nuclei. , keywords =. doi:10.1046/j.1365-8711.2003.06539.x , archivePrefix =. astro-ph/0302328 , primaryClass =

    work page doi:10.1046/j.1365-8711.2003.06539.x 2003

  60. [60]

    Transient Name Server Discovery Report , keywords =

    GaiaAlerts Transient Discovery Report for 2019-06-18. Transient Name Server Discovery Report , keywords =

    2019

  61. [61]

    , keywords =

    The Host Galaxy and Rapidly Evolving Broad-line Region in the Changing-look Active Galactic Nucleus 1ES 1927+654. , keywords =. doi:10.3847/1538-4357/ac714a , archivePrefix =. 2208.01797 , primaryClass =

    work page doi:10.3847/1538-4357/ac714a 1927

  62. [62]

    , keywords =

    Tidal Disruption Events in Active Galactic Nuclei. , keywords =. doi:10.3847/1538-4357/ab2b40 , archivePrefix =. 1904.12261 , primaryClass =

    work page doi:10.3847/1538-4357/ab2b40 1904

  63. [63]

    A new class of flares from accreting supermassive black holes

    A new class of flares from accreting supermassive black holes. Nature Astronomy , keywords =. doi:10.1038/s41550-018-0661-3 , archivePrefix =. 1901.03731 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1038/s41550-018-0661-3 1901

  64. [64]

    Comparison of the X-ray emission from Tidal Disruption Events with those of Active Galactic Nuclei

    A Comparison of the X-Ray Emission from Tidal Disruption Events with those of Active Galactic Nuclei. , keywords =. doi:10.3847/1538-4357/aa9b7c , archivePrefix =. 1703.06141 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.3847/1538-4357/aa9b7c

  65. [65]

    2021, ARA&A, 59, 21, doi: 10.1146/annurev-astro-111720-030029

    Tidal Disruption Events. , keywords =. doi:10.1146/annurev-astro-111720-030029 , archivePrefix =. 2104.14580 , primaryClass =

    work page doi:10.1146/annurev-astro-111720-030029

  66. [66]

    E., & Ho, L

    Estimating Black Hole Masses in Active Galaxies Using the H Emission Line. , keywords =. doi:10.1086/431897 , archivePrefix =. astro-ph/0508335 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/431897

  67. [67]

    A Catalog of Quasar Properties from SDSS DR7

    A Catalog of Quasar Properties from Sloan Digital Sky Survey Data Release 7. , keywords =. doi:10.1088/0067-0049/194/2/45 , archivePrefix =. 1006.5178 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1088/0067-0049/194/2/45

  68. [68]

    , keywords =

    Spectral Properties of Quasars from Sloan Digital Sky Survey Data Release 14: The Catalog. , keywords =. doi:10.3847/1538-4365/ab99c5 , archivePrefix =. 1910.10395 , primaryClass =

    work page doi:10.3847/1538-4365/ab99c5 1910

  69. [69]

    Dissecting Galaxies: Spatial and Spectral Separation of Emission Excited by Star Formation and AGN Activity

    Dissecting galaxies: spatial and spectral separation of emission excited by star formation and AGN activity. , keywords =. doi:10.1093/mnras/stw1754 , archivePrefix =. 1607.05731 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/stw1754

  70. [70]

    , keywords =

    SkyMapper Southern Survey: Second data release (DR2). , keywords =. doi:10.1017/pasa.2019.27 , archivePrefix =. 2008.10359 , primaryClass =

    work page doi:10.1017/pasa.2019.27 2019

  71. [71]

    , keywords =

    An Algorithm for the Relative Scaling of Spectra. , keywords =. doi:10.1086/133039 , adsurl =

    work page doi:10.1086/133039

  72. [72]

    , keywords =

    The Type 1 and Type 2 AGN dichotomy according to their ZTF optical variability. , keywords =. doi:10.1093/mnras/stac3174 , archivePrefix =. 2211.00770 , primaryClass =

    work page doi:10.1093/mnras/stac3174

  73. [73]

    X-ray spectra reveal the reawakening of the repeat changing-look AGN NGC 1566

    X-ray spectra reveal the reawakening of the repeat changing-look AGN NGC 1566. , keywords =. doi:10.1093/mnrasl/sly224 , archivePrefix =. 1811.10289 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnrasl/sly224

  74. [74]

    Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop

    Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop. , keywords =. doi:10.1093/mnras/sty2032 , archivePrefix =. 1805.07873 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1093/mnras/sty2032

  75. [75]

    , keywords =

    Improving the selection of changing-look AGNs through multiwavelength photometric variability. , keywords =. doi:10.1093/mnras/stad1893 , archivePrefix =. 2306.13808 , primaryClass =

    work page doi:10.1093/mnras/stad1893

  76. [76]

    Optical Continuum and Emission-Line Variability of Seyfert 1 Galaxies

    Optical Continuum and Emission-Line Variability of Seyfert 1 Galaxies. , keywords =. doi:10.1086/305813 , archivePrefix =. astro-ph/9802104 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/305813

  77. [77]

    Summary of the content and survey properties

    Gaia Data Release 3. Summary of the content and survey properties. , keywords =. doi:10.1051/0004-6361/202243940 , archivePrefix =. 2208.00211 , primaryClass =

    work page doi:10.1051/0004-6361/202243940

  78. [78]

    J., Dopita, M

    Theoretical Modeling of Starburst Galaxies. , keywords =. doi:10.1086/321545 , archivePrefix =. astro-ph/0106324 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1086/321545

  79. [79]

    N., & Ogilvie, G

    Semi-empirical analysis of Sloan Digital Sky Survey galaxies - III. How to distinguish AGN hosts. , keywords =. doi:10.1111/j.1365-2966.2006.10732.x , archivePrefix =. astro-ph/0606724 , primaryClass =

    work page doi:10.1111/j.1365-2966.2006.10732.x 2006

  80. [80]

    Obscured Active Galactic Nuclei

    Obscured Active Galactic Nuclei. , keywords =. doi:10.1146/annurev-astro-081817-051803 , archivePrefix =. 1806.04680 , primaryClass =

    work page internal anchor Pith review Pith/arXiv arXiv doi:10.1146/annurev-astro-081817-051803

Showing first 80 references.