Abstract We present spatially resolved mass outflow rates of the ionized and molecular gas in the narrow-line region of the Seyfert 1 galaxy NGC 3227. Using long-slit spectroscopy and [O III ] imaging from from the Hubble Space Telescope’s Space Telescope Imaging Spectrograph and Apache Point Observatory’s Kitt Peak Ohio State Multi-Object Spectrograph, in conjunction with Cloudy photoionization models and emission-line diagnostics, we find a peak ionized mass outflow rate of M ̇ ion = 19.9 ± 9.2 M ⊙ yr −1 at a distance of 47 ± 6 pc from the supermassive black hole (SMBH). Using archival data from the Gemini-North Near-infrared Field Spectrograph measuring H 2 2.1218 μ m emission, we find a maximum peak warm molecular outflow rate of M ̇ H 2 ≤ 9 × 10 − 4 M ⊙ yr −1 at a distance of 36 ± 6 pc from the SMBH. Using archival data from the Atacama Large Millimeter/submillimeter Array measuring CO(2–1) emission, we find a maximum peak cold molecular gas mass outflow rate of M ̇ CO ≤ 23.1 M ⊙ yr −1 at a distance of 57 ± 6 pc from the SMBH. For the first time, we calculate spatially resolved gas evacuation timescales for the cold molecular gas reservoirs ostensibly sourcing the outflows, and find that gas evacuating to ∼400 pc from the SMBH occurs on timescales of 10 6.0 –10 7.6 yr. These results indicate that the multiphase active galactic nucleus (AGN) outflows are effective in clearing the inner few hundred parsecs of NGC 3227’s gas content on timescales that may set the AGN duty cycle of 10 5 –10 8 yr.

Jetted active galactic nuclei aligned with our line of sight known as blazars are promising high-energy neutrino source candidates. However, leptohadronic models face challenges in describing neutrino emission within a viable energy budget and their predictive power are limited by the commonly used single-zone approximation and reliance on phenomenological parameters. We tested the scenario where energetic protons are continuously accelerated up to ultra-high energies in inner blazar jets, while accounting for the source energetics and jet dynamics. We present a new leptohadronic model, where a sub-Eddington jet evolves from being magnetically to kinetically dominated. A constant fraction of 10^-6-10^-8 of the electrons and protons picked up by the jet are continuously accelerated to a power-law spectrum. We can estimate their normalization and maximum energies based on the local magnetic field strength, turbulence, and medium density, for which we assumed power-law profiles. The model parameters are thus directly tied to the jet physics and are comparable in number to a single-zone model. We then calculate the emission along the jet, including neutrinos and electromagnetic cascades. Applying the model to IceCube candidate we find that protons accelerated in the inner jet produce a neutrino flux up to ∼100 PeV that is consistent with the public IceCube ten-year point-source data. Proton emission at 0.1 pc describes the X-ray and γ-ray data, while electron emission at the parsec scale describes the optical data. Protons carry a power of about 1% of the Eddington luminosity. The particle spectra follow E^-1.8, with diffusion scaling as E^0.3, ruling out Bohm-like diffusion. Additional particle injection near the broad line region can reproduce the 2017 flare associated to a high-energy neutrino. We also applied the model to the blazar which could be associated with a recent neutrino detected by KM3NeT above 100 PeV. Magnetic acceleration in blazar jets can describe multimessenger observations with viable energetics. Our model constrains jet properties such as the energy-dependent particle diffusion and predicts the spatial distribution of the multiwavelength and neutrino emission along the jet. The results suggest that blazars are efficient neutrino emitters at ultra-high energies, making them prime candidates for future experiments targeting this challenging energy range.

Reverberation mapping (RM) is a powerful tool to determine the extent, structure, and kinematics of the broad-line region (BLR) of active galactic nuclei (AGNs). So far, RM of the BLR has only been performed for recombination lines responding to the varying ionizing continuum. We tested whether $,łambda8446$, attributed to Bowen fluorescence driven by Lyβ pumping, varied on short (day- to week-long) timescales during a 2016 Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) campaign of NGC,4593, and examined how it relates to other emission lines and the ionizing UV continuum. O i We quantified the variability of $,łambda8446$ by its root-mean-square (rms) amplitude. We then extracted integrated light curves of O i O i $,łambda8446$ and other UV and optical emission lines, and compared them with each other and the UV continuum light curve using correlation analyses. In addition, we used archival near-infrared spectra to assess the dominant excitation mechanism of O i $,łambda8446$. We detect, for the first time, variability in $,łambda8446$ on day timescales. The fractional rms amplitude is ∼ 4% over the 4-week campaign. The O i O i $,łambda8446$ light curve reverberates with a delay of ∼ 2.5 days relative to , used as a proxy for Lyβ, detected at a false-alarm probability of 0.6% (significance of ∼ 2.8σ) under our adopted null hypothesis. It closely tracks with only a minor additional delay of sim0.3,days, placing its emission region at essentially the same distance as the Balmer-line weighted BLR. Line ratios indicate that Lyβ pumping is the dominant excitation mechanism for O i $,łambda8446$. Our results establish $,łambda8446$ as the first Bowen fluorescence line to be reverberation-mapped, responding directly to variations in the Lyβ flux. We propose that in future campaigns targeting AGNs with larger BLRs, O i O i could enable dual-driver RM using both the continuum and the pumping line as drivers.

We present the first near-infrared interferometric data of a QSO at z=4. The K-band observations were performed with GRAVITY+ on the VLTI using all four UTs, detecting a differential phase signal that traces the spatially resolved kinematics for both the $. This is oriented so that our line of sight is along an edge of the conical structure, which produces the prominent blue wing on the line profile. A combination of anisotropic line emission and mid-plane opacity leads to the single-sided phase signal. The model is able to qualitatively match both the outflowing ̧iv line profile and the systemic and lines in the broad-line region (BLR). We fit the two lines simultaneously with an updated model that includes distinct rotating and conical outflowing components. For the best-fit model, more than 80% of the line emission from the BLR originates in an outflow with a velocity up to 10^4 km s -1 fluorescent emission. The black hole mass of 8 M$_⊙ that we derive is the highest redshift black hole mass measurement to date obtained directly from BLR dynamics. It is an order of magnitude lower than that inferred from various single epoch scaling relations, and it implies that the accretion is highly super-Eddington. With reference to recent simulations, the data suggest that this QSO is emitting close to its radiative limit in a regime where strong outflows are expected around a polar conical region.

Abstract We present a study determining the spatial offset between the position of the supermassive black hole (as traced through their broad line regions) and the host galaxy in six z > 6 quasars. We determined the host galaxy’s position from ≲ 0 . ″ 10 (≲600 pc) resolution Atacama Large Millimeter/submillimeter Array (ALMA) [C ii ] 158 μ m and corresponding dust continuum imaging. We determined the quasar’s position from ≲400 pc resolution James Webb Space Telescope Near-Infrared Camera (JWST NIRCam) imaging. We estimated the observational uncertainties on the quasar’s position using astrometric data from the Global Astrometric Interferometer for Astrophysics of field stars within the NIRCam images. We find that all six quasars are found within the central ∼400 pc of their host galaxy dust continuum and [C ii ] emission. Apparent offsets seen in rest-frame optical JWST observations are not detected in our ALMA data, suggesting they likely result from dust obscuration rather than a true physical separation between the SMBH and its host galaxy. Kinematic modeling of these data further reveals that none of the galaxies show evidence for recent merger activity, and most of the galaxies can be accurately modeled using a simple disk model. The lack of an offset supports theoretical models that predict that positional offset within these galaxies is either short-lived or intrinsically rare.

Abstract Little red dots (LRDs), high-redshift, compact, red objects with V-shaped spectra, are one of the most exciting and perplexing discoveries made by the James Webb Space Telescope (JWST). While the simplest explanation for LRDs is that they are high-redshift active galactic nuclei (AGN), due to their compactness and frequent association with broad-line emission, the lack of corresponding X-ray emission and observed variability casts doubt on this picture. Here, we simulate LRD light curves using both traditional models for sub-Eddington AGN variability derived empirically from lower-redshift AGN observations and moderately super-Eddington AGN disk models from radiation magnetohydrodynamic simulations to examine the reason for the lack of variability. We find that even though most LRDs have only been observed two to four times in a given wave band, we should still be detecting significantly more variability if traditional sub-Eddington AGN variability models can be applied to LRDs. Instead, our super-Eddington model light curves are consistent with the lack of observed LRD variability. In addition, the ongoing high-cadence nexus campaign will detect changes in magnitude Δ m > 1 for traditional sub-Eddington models, but will only observe significant continuum variability for the lowest-mass LRDs for our super-Eddington AGN models. Even if LRDs lack continuum variability, we find that the ongoing spectroscopic JWST campaign twinkle should observe broad emission line variability as long as soft X-ray irradiation manages to reach the broad-line region from the inner disk. Our models show that super-Eddington accretion can easily explain the lack of continuum variability in LRDs.

Abstract The Fanaroff–Riley radio galaxies exhibit the most extensive radio emissions derived from the active nuclei of galaxies. They morphologically differ from the highly compact and bright radio galaxies observed as gigahertz peaked spectrum and compact steep spectrum sources. Their emissions include jets, lobes, and a central core component, which may expand to larger scales in the future. We study the cores of extended radio galaxies by comparing samples of core-dominated and core-poor populations from FRI radio galaxies. Matching them in redshift, stellar mass, and total radio luminosity, we found no statistically significant differences between the two samples. However, core-dominated FRIs exhibit slightly higher [O III ] luminosity compared to core-poor FRIs. Additionally, the hosts of core-dominated FRIs demonstrate slightly higher surface mass density and lower specific star formation rate. The p -values for the observed differences fall within the marginal range ( p ≲ 0.1), suggesting that the differences may be meaningful and warrant further consideration, although they do not meet the conventional significance threshold ( p < 0.05). We also discuss the possible influences of obscuration, recycling activity, and relativistic beaming that may cause uncertainties and compare the results with those of Mazoochi et al. for FRII radio galaxies.

Abstract We investigate the application of fractional calculus to model stellar dynamics, focusing on resonant relaxation (RR) near a supermassive black hole. Standard theories use the local Fokker–Planck (FP) equation, restricted to Gaussian processes under the central limit theorem (CLT). We argue this is inadequate for RR. We demonstrate that gravitational interactions inherently produce infinite variance in stochastic torques, violating the CLT. Consequently, RR is governed by the generalized CLT and constitutes a superdiffusive Lévy flight. We apply the space-fractional FP equation (space-FFPE), utilizing nonlocal operators, to explore resolutions to observational discrepancies. In transient regimes, the FFPE predicts immediate linear flux (Γ( t ) ∝ t ), consistent with high tidal disruption event (TDE) rates in poststarburst galaxies, whereas local FP models predict significant exponential delay. Furthermore, we demonstrate analytically that nonlocal integral operators permit “barrier jumping,” bypassing bottlenecks like the Schwarzschild Barrier, which local models interpret as severely suppressing extreme-mass-ratio-inspiral (EMRI) rates. We present proof-of-concept N -body simulations that confirm nonlocal RR transport, although the resolution must be improved to rule out enhanced two-body relaxation in the small- N setup. The fractional framework offers a compelling alternative description for nonlocal transport, potentially resolving TDE and EMRI rate questions.

Abstract Carbon monoxide (CO) emission is a widely used tracer of molecular hydrogen (H 2 ) in the interstellar medium, owing to its abundance, low excitation energy, and ease of detection in cold molecular environments, in contrast to H 2 itself. While the CO-to-H 2 conversion factor is often assumed to be constant across the disks of galaxies, deviations are observed in extreme environments such as the central molecular zone (CMZ) in galactic nuclei. Here we present the first estimate of the CO-to-H 2 conversion factor on subkiloparsec scales. We calculate CO-to-H 2 conversion in the Milky Way’s circumnuclear disk/ring at ∼1 pc radius around the Galactic Center black hole. We derive a conversion factor of α CO ≃ 4.5 ± 2.5 M ⊙ (K km s −1 pc 2 ) −1 or X[CO] ≃ (2.1 ± 1.1) ×10 20 cm − 2 ( K km s − 1 ) − 1 . This value is consistent with the Galactic disk but higher than the CMZ.

Supermassive Black Hole and Broad-line Region in NGC 5548: 2023 Reverberation Mapping Results

WPVS,48 is a nearby narrow-line Seyfert 1 galaxy without previous analysis of the broad-line region (BLR) by means of optical spectroscopic reverberation mapping. By studying the continuum and emission line variability of WPVS,48, our aim was to infer the BLR size as well as the mass of the central supermassive black hole (SMBH). We analysed data from a dedicated optical spectroscopic reverberation mapping campaign of WPVS,48 taken with the 10,m Southern African Large Telescope (SALT) at 24 epochs over a period of seven months between December 2013 and June 2014. WPVS,48 shows variability throughout the campaign. We find a stratified BLR, where the variability amplitude of the integrated emission lines decreases with distance to the ionising continuum source. Specifically, the variable emission of Hα, Hβ, Hγ, and He i ,łambda5876 originates at distances of 16.0^ +4.0 _ -2.0 , 15.0^ +4.5 _ -1.9 , 12.5^ +3.5 _ -2.5 , and 14.0^ +2.5 _ -2.1 light-days, respectively, to the optical continuum at 5100,Å. The He ii ,łambda 4686 lag is łesssim 5,days. Based on the high S/N spectra, we identified variable emission of N iii ,łambda4640 and C iv ,łambda4658 in the line complex with He ii ,łambda 4686. We derive interband continuum delays increasing with wavelength up to ∼ 8,days. These delays are consistent with an additional diffuse continuum originating at the same distance as the variable Balmer emission. We derive a central black hole mass of $(1.3_ -0.6 ^ +1.1 ) ≈ 0.39 without correction for inclination. based on the integrated line-widths and distances of the BLR and discuss corrections for the inclination angle. This gives an Eddington ratio L/L_ Edd

Abstract Accretion onto a supermassive black hole can release energy via radiation, jets, or winds, providing feedback effects on the circumnuclear gas environment. However, not all active galactic nuclei exhibit clear signatures of such feedback, and the dynamics of accreting gas on the inner subparsec scales remains poorly understood. Using high-resolution Chandra X-ray grating spectra of Mrk 3, we detect a fast inflowing ionized absorber characterized by redshifted Fe XXV and Fe XXVI absorption lines with confidence level in the 94%–99.6% range. Photoionization modeling reveals the inflowing absorber is located at ≲0.04–0.74 pc, with redshifted velocity decreasing from 6.1 ± 0.5 × 10 3 km s −1 to 3.4 ± 0.3 × 10 3 km s −1 over 11 yr. Only ∼0.6%–3% of the inflowing material is estimated to reach the event horizon. This direct evidence of subparsec scale fueling inflow bridges the gap between the torus and the outer accretion disk. Additionally, a 0.86 keV gas component with subsolar metallicity ( Z ∼ 0.22), outflowing at a velocity of ∼330 km s −1 , is detected in the soft X-ray band with the XMM-Newton Reflection Grating Spectrometer, probably corresponding to a shocked interstellar medium in the narrow-line region (NLR). The simultaneous presence of the apparent decelerating subparsec inflow and the NLR outflow favors a coherent scenario where a putative disk wind or broad-line region clouds may impede or even eject the accretion material, although other possibilities cannot be fully excluded.

The γ-ray–loud blazar , a powerful multiwavelength emitter at z=0.859, underwent an exceptional gigaelectron volt outburst in late 2020 to early 2021. In this work, we present full polarization VLBI imaging at 22, 43, and 86,GHz (11 February 2021) together with contemporaneous single-dish monitoring (OVRO 15,GHz; SMA 226,GHz) and TXS 2013+370 Fermi –LAT light curves to localize the high-energy dissipation site and probe the magnetic field of the inner jet. The images enabled us to study the jet structure and field topology on sub-parsec scales, revealing a compact near-core knot at r =(7.8 , consistent with an external Faraday screen. Performing a cross-correlation of –LAT and 15,GHz light curves revealed a highly significant peak, with the γ rays leading by Δ t=(102 =4.2 ! implies a de-projected separation of Δ r_ μas along with the gigaelectron volt (GeV) flare and a flat core-dominated spectrum (α≳-0.5). The core has strong linear polarization and exhibits a electric vector polarization angle rotation at 86,GHz. The pixel-based and integrated fits we employed yielded a high, uniform rotation measure, mathrm RM 4 -2 Fermi Adopting β_ ̊m app and þeta=4.1^ ̧irc ̧irc γ-15 =(2.71 and locates the GeV emission between the jet apex and sim0.42,pc (in the 1σ range) downstream. Our results do not pinpoint the emission site; rather, they support two valid scenarios. The γ-ray production occurs within the broad-line region (sim0.07,pc), where external-Compton scatters optical/UV photons to γ-rays, and beyond the broad-line region, reaching sim0.42 pc (1σ) within the inner parsecs, where external-Compton scattering of dusty-torus infrared photons dominates. Both scenarios are compatible in the allowed range of emission distances, while opacity-driven core shifts modulate the observed radio–γ delay without requiring large relocations of the dissipation zone.

Abstract In this manuscript, we recheck the spectroscopic properties of SDSS J134733.36+121724.27 (4C+12.50), confirming the presence of the double-peaked [O iii ] λλ 4959, 5007 Å doublet and a broad H α . The former likely results from active galactic nucleus (AGN)-driven biconical outflows, while the absence of a broad H β supports a classification of the source as a Type-1.9 AGN. We analyze its high-quality Sloan Digital Sky Survey (SDSS) optical spectrum after robustly subtracting host galaxy and AGN continuum contributions through a simple stellar population fitting method employing 39 templates and a power-law continuum. Each narrow line of the [O iii ] λλ 4959, 5007 Å doublet is better described by two Gaussian components (blueshifted and redshifted) than by a single Gaussian, as confirmed by the F-test. Broad components are included for both H α and H β , but only H α reveals a significant detection, further supported by a comparison between the SDSS spectrum and that previously reported. These results support that the object is highly consistent with a Type-1.9 AGN classification, and the double-peaked [O iii ] profiles are most likely produced by AGN-driven biconical outflows rather than by a rotating narrow-line region or a dual AGN merger system. Additional observations are still needed to strengthen these conclusions.

Probing the Physical Origin of the Balmer Decrement in the Broad-line Region of Nearby Active Galactic Nuclei via Spectral Variability

Abstract We present a high-resolution X-ray spectroscopic study of the narrow-line Seyfert 1 galaxy NGC 4051 using two XMM-Newton high-resolution Reflection Grating Spectrometer observations. The spectra reveal three distinct layers of photoionized gas flowing outward from the central black hole: a low-ionization phase (LIP), a higher-ionization phase (HIP), and a high-velocity and high-ionization phase (HVIP). Each absorber leaves characteristic imprints on the soft X-ray spectrum. While the LIP and HVIP are fully consistent with being in ionization equilibrium with the central radiation field over the course of the ∼250 ks spanned by the two observations, the HIP shows a significant change in ionization (3.8 σ ), suggesting nonequilibrium. By modeling the two spectra with our time-dependent photoionization code ( TEPID ), we constrain the density of the HIP gas to log n H = 7 . 7 − 0.9 + 0.2 and estimate its distance to be about R = 0.4 5 − 0.09 + 0.80 lt-day from the black hole, corresponding to R = 400 0 − 800 + 7000 gravitational radii. In contrast, the narrow soft X-ray emission lines remain constant, consistent with an origin in the more extended narrow-line region. Our results show the value of combining high-resolution and time-resolved spectroscopy to probe the structure, physical conditions, and variability of active galactic nucleus outflows.

Quasi-periodic eruptions (QPEs) are repeating soft X-ray flares associated with galactic nuclei. Several recent works have found evidence that the accretion flow in the galactic nuclei of QPEs is of recent origin, and that it is unlike canonical active galactic nuclei (AGN). A precursor tidal disruption event has been observed in a few cases. In this work we report new radio observations of the QPE host galaxy RXJ 1301.9+2747 taken at 5.0 GHz with the High Sensitivity Array (HSA), to complement archival 1.7 GHz observations reported previously. Our new observations confirm the presence of a highly compact radio source in RXJ 1301.9+2747, which is smaller than 0.9 × 0.4 pc at 5.0 GHz. The nonsimultaneous very long baseline interferometry (VLBI) compact flux of the source is consistent with a negative spectral index, and thus is similar to the larger non-VLBI scale radio spectral index. Contrary to earlier results at 1.7 GHz, we find the 5 GHz emission offset from the optical Gaia position, which may be due to dust extinction in the host galaxy. In addition, there is a significant offset between the 1.7 and 5.0 GHz data, which may result from astrophysical uncertainties in the calibration source. This sheds new light on the elusive properties of the radio-detected QPE sources. Consistent with previous results, our observations disfavor a star formation or jet-core-region origin of the radio emission. We cannot rule out a reconnection-driven scenario for the radio emission, but we favor a remnant jet or outflow scenario. This is overall in agreement with the radio properties of radio-detected QPE sources at lower angular resolution.

We report the discovery of an extremely high-velocity outflow (EHVO) in the most luminous QSO ( L Bol ∼ 2.29 × 10 48 erg/s), named SMSS J2157-3602, at z = 4.692. Combined XSHOOTER and NIRES observations reveal that the EHVO reaches a maximum velocity of v max ∼ 0.13 c and persists over rest-frame timescales of a few months up to one year. SMSS J2157-3602 also exhibits one of the highest balnicity index values discovered for an EHVO so far. In addition, the blueshifted CIV emission traces a high-velocity ( v CIV 50 ∼ 4660 km/s) outflow from the broad-line region (BLR). Thanks to an XMM-Newton observation, we were also able to reveal the X-ray weak nature of this QSO, which likely prevents the overionization of the innermost disk atmosphere and facilitates the efficient launch of the detected EHVO and BLR winds. The extraordinary luminosity of SMSS J2157-3602 and the extreme velocity of the EHVO make it a unique laboratory for testing active galactic nucleus (AGN) driven feedback under extreme conditions. Current uncertainties on the outflow’s location and column density strengthen the case for a dedicated follow-up, which will be essential to assess the full feedback potential of this remarkable quasar.

Context. The single-epoch virial method is a fundamental tool for estimating supermassive black hole (SMBH) masses in large samples of active galactic nuclei (AGNs) and has been extensively employed in studies of SMBH–galaxy coevolution across cosmic time. However, since this method is calibrated using reverberation-mapped AGNs, its validity across the entire AGN population remains uncertain. Aims. We aim to examine the breathing effect–the variability of emission line widths with continuum luminosity–beyond reverberation-mapped AGNs, to assess the validity and estimate potential systematic uncertainties of single-epoch virial black hole mass estimates. Methods. We constructed an unprecedentedly large multi-epoch spectroscopic dataset of quasars from Sloan Digital Sky Survey data release 16 (SDSS DR16), focusing on four key broad emission lines (H α , H β , Mg II , and C IV ). We assessed how breathing behavior evolves with the rest-frame time interval between observations. Results. We detect no significant breathing signal in H α , H β , or Mg II at any observed timescale. In contrast, C IV exhibits a statistically significant anti-breathing trend, most prominent at intermediate timescales. Notably, for H β , which has shown breathing in previous reverberation-mapped samples, we recover the effect only in the small subset of quasars with clearly detected broad-line region (BLR) lags and only during the epochs when such lags are measurable–suggesting that both the lag and breathing signals are intermittent, possibly due to a weak correlation between optical and ionizing continua. These results highlight the complex, variable, and timescale-dependent nature of line profile variability and underscore its implications for single-epoch black hole mass estimates.

Abstract Little Red Dots (LRDs) are compact sources at z > 5 discovered through JWST spectroscopy. Their spectra exhibit broad Balmer emission lines ($\gtrsim 1000\rm ~km~s^{-1}$), alongside absorption features and a pronounced Balmer break – evidence for a dense, neutral hydrogen medium, in which the n = 2 state is significantly populated. When interpreted as arising from AGN broad-line regions, inferred black hole masses from local scaling relations exceed expectations given their stellar masses, challenging models of early black hole–galaxy co-evolution. However, radiative transfer effects in dense media may also impact the formation of hydrogen emission lines. We model three scattering processes shaping hydrogen line profiles: resonance scattering by hydrogen in the n = 2 state, Raman scattering of UV radiation by ground-state hydrogen, and Thomson scattering by free electrons. Using 3D Monte Carlo radiative transfer simulations, we examine their imprint on line shapes and ratios. Resonance scattering produces strong deviations from Case B flux ratios, clear differences between Hα and Hβ, and encodes gas kinematics in line profiles but cannot broaden Hβ due to conversion to Paα. While Raman scattering can yield broad wings, scattering of the UV continuum is disfavored given the absence of strong FWHM variations across transitions. Raman scattering of higher Lyman-series emission can produce Hα/Hβ wing width ratios of ≳ 1.28, agreeing with observations. Thomson scattering can reproduce the observed $\gtrsim 1000~\rm km\, s^{-1}$ wings under plausible conditions – e.g., Te ∼ 104 K and $N_{\rm e}\sim 10^{24}\rm ~cm^{-2}$ – and lead to black hole mass overestimates by factors ≳ 10. Our results provide a framework for interpreting hydrogen lines in LRDs and similar systems.