654 indexed papers · 430 research notes

Research archive

2025-05-13 · 2505.08885v1

XMM-Newton Conclusively Identifies an Active Galactic Nucleus in a Green Pea Galaxy

Peter G. Boorman, Jiří Svoboda, Daniel Stern, et al.

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Deep XMM-Newton monitoring of the Green Pea SDSS J082247.66+224144.0 (z=0.216) tests for an elusive low-luminosity AGN long hinted by its Γ≈2, L2–10 keV≈10^42 erg s^-1 spectrum. Across 6.2 years (rest-frame), the hard 2–10 keV luminosity remains stable while the soft 0.5–2 keV flux drops by ~60%, yielding a markedly harder second epoch. Swapped-epoch spectral posterior checks and SDSS line decomposition (requiring a broad Hα despite BPT star-forming narrow lines) point to transient, low-column obscuration as the only viable explanation. This work delivers the first conclusive X-ray AGN identification in a Green Pea, strengthening the case that faint AGN could have contributed to reionisation and clarifying local analogs of JWST Little Red Dots.

X-ray low-z obscured AGN variability broad Balmer reionization

2025-05-07 · 2505.04826v1

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XXII. Chandra observations of narrow-line quasar candidates at z>6

K. Iwasawa, R. Gilli, F. Vito, et al.

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Chandra followed up four z>6 SHELLQs narrow-line quasar candidates chosen for luminous Lyα and faint UV continua, and found no X-ray detections, placing L2–10 keV < 2×10^44 erg/s (2σ; Γ=2). JWST/NIRSpec reveals weak broad Balmer bases beneath narrow cores, while strong [O III] would predict Lx ≈ 10^45 erg/s from low‑z scaling, in stark tension with the Chandra limits. The authors argue for heavily buried nuclei—either Compton-thick columns in dense ISM or an inclined, inflated inner disc in supercritical accretion—making these sources higher-luminosity analogs of JWST-selected broad-line AGN at reionization. The work clarifies how extreme Lyα–bright, UV-faint quasars can hide powerful engines early on.

obscured AGN X-ray luminous quasar high-z spectroscopy

2025-05-07 · 2505.04825v1

SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at z > 6

Yoshiki Matsuoka, Masafusa Onoue, Kazushi Iwasawa, et al.

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From the SHELLQs wide-field UV survey, the team followed 13 z>6, Lyα-luminous galaxies with JWST/NIRSpec and uncovered obscured quasars. Seven of eleven narrow‑Lyα systems show broad H I Balmer and He I components—but not in [O III]—with Balmer decrements indicating mild obscuration (0<Av<3), identifying them as UV‑obscured counterparts of luminous EoR quasars. Virial lines imply MBH≈10^(7.8–9.1) Msun with sub‑Eddington to Eddington accretion; most BL sources are unresolved and display LRD‑like blue‑UV/red‑optical colors. The AGN incidence among similarly bright Lyα emitters (≥2×10^−8 Mpc^−3) is comparable to classical quasar densities, implying a substantial obscured SMBH population previously missed by UV‑bright surveys.

obscured AGN luminous quasar high-z broad Balmer spectroscopy JWST AGN

2025-04-22 · 2504.15913v1

A Massive Gas Outflow Outside the Line-of-Sight: Imaging Polarimetry of the Blue Excess Hot Dust Obscured Galaxy W0204-0506

Roberto J. Assef, Marko Stalevski, Lee Armus, et al.

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VLT/FORS2 imaging polarimetry of the blue-excess Hot DOG WISE J020446.13–050640.8 (W0204–0506) finds a spatially integrated UV polarization of 24.7 ± 0.7% in R_Special, clinching a scattered-light origin for the faint blue continuum. The source is resolved, showing a polarization fraction and angle gradient aligned with the HST/WFC3 morphology, which SKIRT radiative-transfer models reproduce with a dusty conical polar outflow that starts at the sublimation radius, has half-opening angle ≤50°, and is viewed at inclination ≥45°, favoring graphite-rich dust. Inferred gas mass and outflow velocity fall within ranges seen for [O III] outflows in other Hot DOGs, though the feedback impact on the host remains uncertain. The work showcases imaging polarimetry as a geometry probe for dusty quasar outflows complementary to spectroscopy.

obscured AGN outflows luminous quasar

2025-04-18 · 2504.13658v1

SRGAJ230631.0+155633: an extremely X-ray luminous, heavily obscured, radio-loud quasar at z=0.44 discovered by SRG/ART-XC

Grigory Uskov, Sergey Sazonov, Igor Lapshov, et al.

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SRGA J230631.0+155633 is a z=0.4389, type 2, radio‑loud quasar uncovered by SRG/ART‑XC (4–12 keV) and followed up near‑simultaneously with ART‑XC and Swift/XRT in June 2023, revealing heavy absorption with N_H ≈ 2×10^23 cm^-2. Its intrinsic 2–10 keV luminosity declined from (6^{+6}_{−3})×10^45 erg s^-1 during the 2020–2021 all‑sky scans to (1.0^{+0.8}_{−0.3})×10^45 erg s^-1 in 2023, indicating strong rest‑frame ~1 yr variability while remaining quasar‑luminous. Radio imaging shows a core plus two extended lobes consistent with a giant FR II radio galaxy. Multi‑wavelength constraints imply L_bol ~6×10^46 erg s^-1 and M_BH ~1.4×10^9 M_⊙ (λ_Edd ~0.3), making this one of the most luminous obscured quasars out to z ≈ 0.5 and a nearby laboratory for buried SMBH growth.

obscured AGN luminous quasar X-ray radio variability low-z

2025-04-14 · 2504.10731v1

Unveiling faint X-ray AGN populations in the NewAthena era: Insights from cosmological simulations

Nuno Covas, Israel Matute, Stergios Amarantidis, et al.

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From a TNG300-based 10 deg^2 SMBH light cone with post-processed X-ray properties, the authors run end-to-end NewAthena/WFI simulations via SIXTE to stress-test faint and high‑z AGN performance. The mock predicts a 5× excess of faint AGN versus current X‑ray constraints, plausibly reconciled by a higher Compton‑thick fraction and intrinsic X‑ray weakness hinted by recent JWST work. The simulated survey yields ~250,000 AGN (≈20,000 at z>3) and ~35 at z>6, with only log L_X ≳ 43.5 detectable in the EoR and a significant CTK component out to z>4. These results argue NewAthena can directly probe early SMBH growth while informing instrument trades and survey tiling.

X-ray simulation high-z obscured AGN demographics

2025-04-14 · 2504.10596v1

An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals

Carolina Andonie, David M. Alexander, Claire Greenwell, et al.

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Introduces the 4MOST IR AGN survey, a ~10,000 deg^2, rAB≤22.8 program targeting ≈212k mid-IR–selected obscured AGN via unWISE colors plus an r−W2≥5.9 mag cut. Using X-ray spectral constraints and UV–far-IR SEDs in four deep fields, they forecast 80–87% AGN purity with ≈70% obscured (NH>10^22 cm−2) and that ≈80% of targets will evade even the deepest eROSITA exposures. About 55% will be quasar-luminous (LAGN,IR>10^45 erg s−1) at z≈0.5–3.5 in massive (10^10–10^12 M⊙) hosts, with ≈33% in starbursts. This 100× expansion over prior spectroscopic obscured-IR samples will deliver a uniform census of heavily absorbed, X-ray–faint quasars complementing the 4MOST X-ray AGN survey.

obscured AGN demographics spectroscopy luminous quasar

2025-04-04 · 2504.03422v1

XXL-HSC: Host properties of X-ray detected AGNs in XXL clusters

E. Drigga, E. Koulouridis, E. Pouliasis, et al.

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Using 82 X-ray AGN within 4 r500 of 164 XXL clusters (z ≲ 1) and deep HSC imaging, the authors classify host morphologies (Statmorph + visual) and assess obscuration and SFR via X-ray hardness ratios, optical spectra, and SEDs. They find a moderately significant excess of cluster AGN hosted by merging/disturbed galaxies relative to non-active cluster members and field AGN, with the signal concentrated in the outskirts (≈1–2 r500). Clusters also show a higher share of X-ray-hard (likely obscured) AGN than the field, especially in the outskirts. Together, the results point to mergers/interactions in cluster outskirts as key drivers of both AGN triggering and obscuration.

X-ray obscured AGN demographics low-z

2025-04-02 · 2504.01852v1

Deciphering the Nature of Virgil: An Obscured AGN Lurking Within an Apparently Normal Lyman-α Emitter During Cosmic Reionization

Pierluigi Rinaldi, Pablo G. Pérez-González, George H. Rieke, et al.

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JWST/MIRI imaging plus deep NIRSpec/PRISM place the LAE “Virgil” at z=6.6379 and reveal Little Red Dot–like photometry with an extreme color F444W−F1500W=2.84±0.04, and a strongly rising mid-IR SED. SED fits across multiple codes favor an obscured AGN whose IR slope and UV excess resemble blue-excess HotDOGs. The host shows subsolar metallicity, low–moderate dust, and high ionization/electron temperature; UV and Hα SFRs suggest Virgil is entering or fading a burst. High‑z line‑ratio diagnostics (e.g., O32–R23, Ne3O2) nominally flag AGN, though this is ambiguous after accounting for redshift evolution; a tentative broad Hα improves residuals only marginally, while the new 15 μm data strengthen the AGN case and highlight MIRI’s leverage on early black‑hole growth.

LRD obscured AGN JWST AGN high-z spectroscopy reionization

2025-04-01 · 2504.01103v1

JWST reveals the diversity of nuclear obscuring dust in nearby AGN: nuclear isolation of MIRI/MRS datacubes and continuum spectral fitting

Omaira González-Martín, Daniel J. Díaz-González, Mariela Martínez-Paredes, et al.

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The authors PSF-isolate nuclear mid-IR emission in 21 nearby (z<0.05) AGN with a new tool (MRSPSFisol) and fit the continuum using multiple dust libraries. Twelve nuclei achieve good fits (chi2/dof<2), typically with a flared-disk model combining clumpy and smooth dust and allowing grain size to vary; two prefer disk+wind and one the classical clumpy torus. About 40% resist all models because of extreme silicate profiles plus pervasive water-ice and aliphatic hydrocarbon absorption, pointing to missing chemistry. This establishes JWST/MRS as a clean nuclear isolator and shows that next-generation dust models must capture more complex compositions.

JWST AGN obscured AGN spectroscopy low-z

2025-03-25 · 2503.19915v1

A New Hope for Obscured AGN: The PRIMA-NewAthena Alliance

Luigi Barchiesi, F. J. Carrera, C. Vignali, et al.

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Simulation-driven forecast of a full obscured-AGN census using the far-IR PRIMA plus X-ray NewAthena, built on X-ray background synthesis models and Deep/Wide survey layouts. PRIMA dominates for heavily obscured and Compton-thick accretors, yielding an expected 7500 CT-AGN detections per square degree, while NewAthena preferentially recovers the most luminous, unobscured, and moderately obscured sources. Together they out-perform past IR efforts—PRIMA alone delivers ~60× Herschel source counts over the same area—and enable a precise BHAD history to z≈8. The alliance is pitched as the cleanest route to reveal the true CT-AGN contribution to cosmic BH growth.

obscured AGN simulation X-ray demographics high-z

2025-03-24 · 2503.19078v1

MEGA Mass Assembly with JWST: The MIRI EGS Galaxy and AGN Survey

Bren E. Backhaus, Allison Kirkpatrick, Guang Yang, et al.

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MEGA is a 67 hr, four-band MIRI imaging program in the EGS (25 pointings; 70 arcmin^2) that adds F770W–F2100W coverage over 68.9% of CEERS NIRCam, targeting obscured galaxy and SMBH growth near Cosmic Noon. The team augments the JWST pipeline with warm‑pixel masking and iterative super–background subtraction, delivering mosaics with 5σ depths of ≈0.18, 0.41, 1.26, and 4.10 µJy in F770W, F1000W, F1500W, and F2100W. They release a photometric catalog and new galaxy number counts in all four bands, extending the faint mid‑IR regime over wider area than prior JWST fields. This fills the mid‑IR gap in EGS, enabling PAH‑based SFRs and dusty AGN selection to sharpen constraints on coupled galaxy–black hole growth.

obscured AGN demographics

2025-03-21 · 2503.17183v1

Halfway to the Peak: ice absorption bands at $z\approx0.5$ with JWST MIRI/MRS

Anna Sajina, Alexandra Pope, Henrik Spoon, et al.

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JWST/MIRI–MRS spectroscopy of the dusty starburst–AGN composite SSTXFLS J172458.3+591545 (z=0.494) yields the first combined extragalactic detections of CO2, CO, XCN, and H2O ices, with gas‑phase CO alongside solid CO. Ice-band profiles match Galactic/local templates, and their decomposition (polar‑dominated XCN and CO complexes) plus the silicate depth imply a compact, dense, cold nucleus with n>10^5 cm^-3, T≈20–90 K, and A_V≈6–7; [NeV]/[NeVI] confirm a deeply buried AGN. The authors introduce τ_Si versus τ_CO2/τ_Si as a diagnostic that jointly traces total dustiness and dust clumpiness along the line of sight. Together, these results showcase MIRI’s power to map dust composition and geometry well beyond the local Universe.

obscured AGN spectroscopy low-z

2025-03-19 · 2503.15317v1

Euclid Quick Data Release (Q1). First Euclid statistical study of galaxy mergers and their connection to active galactic nuclei

Euclid Collaboration, A. La Marca, L. Wang, et al.

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Using Euclid Q1 Deep Fields, the team builds a stellar‑mass–complete (M*>10^9.8 Msun) sample at 0.5<z<2, identifies major mergers with CNNs trained on simulations, and selects AGN via X‑ray, optical spectroscopy, MIR colours, and I_E‑band PSF decompositions. Across all AGN selections, mergers host an AGN excess by factors of 2–6, and the AGN merger fraction rises with point‑source contribution f_PSF up to ~0.55 before declining. In luminosity terms, f_merg increases with L_PSF, exceeding 50% for L_PSF>2×10^43 erg/s at z<0.9 and becoming dominant only above ~10^45 erg/s at z>0.9; for X‑ray AGN, f_merg also increases with L_bol, with AGN mostly in mergers at L_bol>10^45 erg/s. This ties major mergers to the most powerful, dust‑obscured SMBH growth phases, with spectroscopic trends weaker due to small samples.

demographics obscured AGN X-ray spectroscopy

2025-03-14 · 2503.11611v1

A Census of the Most Obscured Galaxy Nuclei over Cosmic Time to be revealed by PRIMA

Fergus R. Donnan, Dimitra Rigopoulou, Ismael García-Bernete, et al.

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Concept study for the 1.8 m far‑IR PRIMA mission shows how to census the most buried galaxy nuclei across cosmic time. PRIMAger (25–235 um) photometry captures rest‑frame 9.8 um silicate absorption from z=2–7, enabling color selections that recover local CONs and scale to high z. FIRESS low‑resolution (R~100) spectroscopy to z~7 would detect PAHs, ice bands, and warm‑gas diagnostics even when high‑ionization lines are quenched, yielding redshifts and column densities. Simulations plus local (U)LIRG templates (NGC 4418 vs NGC 7714) suggest large, confusion‑mitigated yields in 1500 h/deg^2 surveys, making PRIMA pivotal for the obscured phase of SMBH growth.

obscured AGN demographics high-z

2025-03-05 · 2503.03547v1

Exploring the physical properties of Type II Quasar candidates at intermediate redshifts with CIGALE

P. A. C. Cunha, A. Humphrey, J. Brinchmann, et al.

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CIGALE SED fits are used to derive SFR, M*, AGN luminosity, and AGN fraction for 366 machine‑learned Type II quasar candidates in the redshift desert (median z≈1.1), then benchmarked against SPRITZ populations and literature samples. On the SFR–M* plane many candidates sit above the main sequence at their redshift, while a tail appears quenched, pointing to episodes of enhanced star formation alongside possible feedback or obscured SF. The inferred properties align with SPRITZ composite systems and AGN2, supporting their obscured‑AGN nature and validating machine‑learning selection beyond simple colour–colour cuts.

obscured AGN QSO demographics

2025-01-28 · 2501.16708v1

BASS XLV: Quantifying AGN Selection Effects in the Chandra COSMOS-Legacy Survey with BASS

Yarone M. Tokayer, Michael J. Koss, C. Megan Urry, et al.

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Uses local BASS analogs with well-characterized 0.5–195 keV spectra, forward-modeled into the CCLS redshift–luminosity–exposure space and re-fit with the CCLS pipeline to quantify obscuration biases. Finds Chandra would miss 53.3% (563/1056) of simulated obscured (NH>10^22 cm^-2) sources, and even detected ≥30-count spectra have NH systematically overestimated. The strongest failure mode is for CT best-fits (NH≥10^24 cm^-2), where 66.7% (18/27) are actually unobscured (NH<10^22 cm^-2). Results imply deep <10 keV surveys overstate the rise of the obscured fraction and the fraction of luminous obscured AGN, motivating forward modeling, multi-wavelength obscuration tracers, and higher-sensitivity missions like AXIS.

X-ray obscured AGN simulation demographics low-z

2025-01-23 · 2501.14072v1

Estimating Black Hole Masses in Obscured AGN from X-ray and Optical Emission Line Luminosities

S. LaMassa, I. Farrow, C. M. Urry, et al.

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Tests a proxy-based black hole mass estimator for obscured AGN that infers FWHM_bHα from the narrow-line ratio L[O III]/L_nHβ and λL5100 from either intrinsic 2–10 keV X-rays or narrow lines, using 99 local Swift-BAT/BASS AGN. The two λL5100 proxies differ by a mean −0.32 ± 0.68 dex (narrow-line estimate lower than X-ray), implying ≈2× MBH uncertainty from the luminosity choice. Compared to virial masses from broad Paschen lines (14 Paα, 12 Paβ), the proxy MBH is higher by 0.39 ± 0.44 dex and 0.48 ± 0.51 dex, respectively, though still within the scatter. σ*-based MBH for 151 BASS AGN agrees on average within 0.08 dex but with large ≈0.74 dex scatter, so the method scales to large samples with overall ≈3–5× uncertainty and a possible mild high bias needing more data.

obscured AGN X-ray spectroscopy low-z

2025-01-23 · 2501.14026v1

Luminous Mid-IR Selected Type-2 Quasars at Cosmic Noon in SDSS Stripe82 I: Selection, Composite Photometry, and Spectral Energy Distributions

Ben Wang, Joseph F. Hennawi, Zheng Cai, et al.

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WISE W4>5 mJy selection in SDSS Stripe 82 yielded 24 candidates, with GNIRS (all) plus LRIS (18/24) confirming 23 luminous Type‑2 QSOs at 0.88<z<2.99, including 12 at z>2. Multi‑band photometry (DESI Legacy, PS1, UKIDSS, Spitzer, WISE) enables rest‑frame 0.1–10 μm composite photometry and AGNfitter SEDs. The IR is torus‑dominated with average L_torus ≈10^46.84 erg s−1; inferred L_bol spans 10^46.28–10^47.49 erg s−1 and Eddington masses ~10^8.18–10^9.39 M⊙, and the sample is redder with brighter tori than earlier Type‑2 SEDs. Their SED shapes closely resemble JWST “little red dots,” highlighting mid‑IR selection as an efficient path to luminous z>2 Type‑2s; a key open point is the origin of the rest‑UV/optical light (scattered, stellar, or a reddened disk).

obscured AGN QSO luminous quasar spectroscopy high-z

2025-01-21 · 2501.12449v1

Intervening nuclear obscuration changing the X-ray look of the $z\approx6$ QSO CFHQS J164121+375520

Fabio Vito, William Nielsen Brandt, Andrea Comastri, et al.

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The authors re-monitor the z=6.025 QSO CFHQS J164121+375520 (J1641) with Chandra and rest‑UV imaging in 2022–2024 after a dramatic X-ray dimming seen between 2018 and 2021. J1641 is now detected only in the hard 2–7 keV band, while its soft 0.5–2 keV flux has faded by >20× relative to 2018, establishing it as an X‑ray changing‑look quasar at z>6. They attribute the transition to intervening, ongoing Compton‑thick obscuration along our line of sight—potentially a thickened inner disk/failed wind or an occultation by dust‑free sub‑pc clouds—with the near‑constant rest‑UV light curve supporting obscuration over intrinsic fading. Catching such events in the reionization era offers a new handle on how rapidly growing SMBHs are fueled and shrouded.

QSO high-z X-ray obscured AGN variability

2025-01-20 · 2501.11491v1

MIDIS: Quantifying the AGN component of X-ray-detected galaxies

Steven Gillman, John P. Pye, Almudena Alonso-Herrero, et al.

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Using MIDIS MIRI 5.6 μm imaging in the HUDF cross-matched to the CDF-S 7 Ms catalog, the authors morphologically decompose 31 X-ray sources (24 AGN; z≈0.5–3) with visual, Sérsic+PSF, and non-parametric classifiers to isolate unresolved nuclear emission at rest-frame ~2 μm. They find ≥70% show an unresolved MIRI component with unresolved-to-total 2 μm flux fractions spanning ~0.2–0.9, and at Lx>10^43 erg s^-1 the 2 μm point-source luminosities align with local AGN relations. At lower X-ray luminosities, they report an excess 2 μm nuclear component relative to pre-JWST expectations, plausibly linked to Compton-thick AGN and/or compact nuclear starburst/merger activity. The work demonstrates that MIRI can robustly quantify nuclear IR emission in faint X-ray sources and clarifies the AGN/host balance across Cosmic Noon.

X-ray JWST AGN obscured AGN

2025-01-16 · 2501.09602v1

The NuSTAR view of five changing-look active galactic nuclei

Bing Lyu, Zhen Yan, Xue-bing Wu, et al.

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NuSTAR multi-epoch X-ray spectra of five CLAGNs (ESO 362-G18, NGC 1365, NGC 4151, NGC 5548, NGC 7582) are fit with phenomenological and clumpy-torus models to track Γ, L2–10 keV/LEdd, and NH,los. The authors find a positive Γ–(L2–10 keV/LEdd) correlation and, for four objects, a strong anti-correlation between NH,los and L2–10 keV/LEdd, with ESO 362-G18 standing out as an exception. They argue this links changing-obscuration to accretion-driven evolution: a disc wind that strengthens with accretion rate pushes line-of-sight clouds outward, lowering NH at moderate inclinations. The trends persist across model choices, tying CLAGN absorption changes to the same engine that drives changing-state behavior.

obscured AGN X-ray variability low-z