arXiv subjects

Aaron J. Barth

Publications and source records attributed to Aaron J. Barth.

At least 19 recordsLinked to original sources

arXiv2026

A $z \sim$ 6.2 Quasar on the Local M$_{\rm BH}$-$σ_{\rm \ast}$ Relation Quenching Its Host Galaxy from the Aether Survey

We report JWST/NIRSpec integral field unit (IFU) observations of the quasar J1512$+$4422 at $z \sim 6.2$ from the Aether survey. At $\sim$900 Myr after the Big Bang, this object already lies on the $M_{\rm BH}$-$σ_\ast$ relation found in the local universe, with an $M_{\rm BH} \simeq 8.9\times10^8\,M_\odot$ and a stellar velocity dispersion $σ_\ast \simeq 288$ km s$^{-1}$. We detect an outflow with a velocity of $\sim$478 km s$^{-1}$ in the nuclear region, which likely extends to $\sim$3.2 kpc in projection and has a median velocity of $\sim$352 km s$^{-1}$. The outflow dynamical time scale ($\sim$ 9 Myr) is consistent with the time scale of the current quenching process based on the star formation history as reported previously. The total mass outflow rate (92.6$^{+92.6}_{-74.1}$ M$_{\odot}$ yr$^{-1}$) is larger than the current star formation rate (0.9$^{+3.8}_{-0.8}$ or 4.3$^{+5.8}_{-3.7}$ M$_{\odot}$ yr$^{-1}$), and the total kinetic energy outflow rate (0.6$^{+0.6}_{-0.5}$\% of quasar luminosity) meets the threshold for negative quasar feedback as suggested by simulations. These results suggest that the outflow is capable of suppressing/quenching the star formation activity within the host galaxy. Furthermore, J1512$+$4422 exhibits $σ_\ast$, stellar mass and size similar to those of $z \gtrsim$ 3 quiescent/post-starburst galaxies, implying a link between the two. Overall, for objects like J1512$+$4422, the evolution of their SMBHs and host galaxies appears to be tightly coupled within the first billion years. The quasar feedback likely plays a critical role in both placing them on the $M_{\rm BH}$--$σ_\ast$ relation and quenching.

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arXiv2026

Detection of an Extended Ly$α$ Halo around a $\textit{z}=6.64$ Broad Absorption Line Quasar with the Keck Cosmic Web Imager

We present the first results from a program searching for extended Ly$α$ halos around high redshift ($ z \gtrsim 6.5$) quasars using the red channel of the Keck Cosmic Web Imager (KCWI). Our observations reveal a Ly$α$ halo extending to $\simeq11$ pkpc around the $z=6.64$ broad absorption line quasar J0910$-$0414. The Ly$α$ velocity field displays a rotation-like gradient, and the gas velocity dispersion is consistent with gravitationally dominated motion ($σ_{\mathrm{Lyα}}<300$ km s$^{-1}$). Comparison with the $[\mathrm{C\;II}]$ kinematics of the host galaxy core from ALMA observations shows that the Ly$α$-emitting gas extends over a much larger region, shows distinct kinematics, and has a smaller velocity dispersion ($σ_{\mathrm{Lyα}} \simeq 0.6σ_{\mathrm{[C\;II]}}$). The Ly$α$ spectral region of the quasar is largely obscured by a deep $\mathrm{N\;V}$ absorption trough, and as a result, roughly $55\%$ of the total Ly$α$ flux is from the extended halo. These observations demonstrate the potential of KCWI for probing the cool gas reservoir that fuels the growth of quasars and their hosts in the epoch of reionization.

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arXiv2026

AGN STORM 2. XII. Ground-Based Optical Photometry and Lag Measurements of Mrk 817

We present the ground-based imaging campaign and light curves of Markarian 817 as part of the multiwavelength monitoring program AGN STORM\,2. Observations were carried out over 1.4 years in \emph{uBgVriz} filters, with a median cadence of 0.4 days in \emph{g}. Reverberation lags are measured using three methods (ICCF, JAVELIN, and PyROA) with the Swift UVW2 band (1928 Å) as the reference light curve. The ICCF centroid lags range from $3.0\pm0.8$ days for the $u$ band up to $7.9\pm1.5$ days for $z$, and are consistent with a $τ\propto λ^{4/3}$ dependence, the relation expected for lamp-post reprocessing by a Shakura-Sunyaev disk. Lags measured with the other methods are systematically shorter, and deviate from a $λ^{4/3}$ power-law spectrum at long wavelengths. The lags exceed thin-disk reprocessing predictions by factors of $\sim$3-6, similar to the ``disk size discrepancy'' seen in other Seyfert galaxies. We divide the campaign into three epochs with different levels of mean luminosity and X-ray obscuring column density and find that the lags vary by as much as a factor of 2 between epochs. The intrinsic spectral energy distribution is bluer and brighter during the first third of the campaign, and the longest continuum reverberation lags are obtained during that period. These results suggest that changes in ionizing luminosity can produce large variations in continuum lags on short timescales by altering the diffuse continuum luminosity emitted by the broad-line region and/or obscuring outflow, although changes in obscuration between the central engine and broad-line region may also contribute to the lag variations.

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arXiv2026

Can BLR line profile shape improve single-epoch black hole mass estimates?

The virial coefficient ($f$), which is meant to encapsulate broad-line region (BLR) geometry and kinematics, remains one of the largest sources of systematic uncertainty in black hole mass estimates for Active Galactic Nuclei (AGNs). While the use of a sample average $\langle f \rangle$ enables black hole mass estimates across large samples and cosmological distances, individual AGNs may deviate from this average due to differences in BLR structure and viewing angle. In previous work, we reported marginal evidence for a correlation between $f$ and the shape of the broad H$β$ emission line, $\log_{10}(\mathrm{FWHM}/σ)$. In this work, we update our sample to include ten new sources with CARAMEL BLR dynamical modeling, increasing both the black hole mass range and statistical power of our analysis. We find marginal evidence for a correlation between $f$ and $\log_{10}(\mathrm{FWHM}/σ)$, with a slope and intrinsic scatter consistent with previous results. The confirmation of this trend across a larger sample further supports the idea that line profile shape may reflect BLR properties in a way that directly impacts $f$. If confirmed with future BLR dynamical modeling of sources within a wider range of $\log_{10}(\mathrm{FWHM}/σ)$, this relationship could enable empirical estimates of the virial coefficient and improve single-epoch black hole mass estimates across cosmic time.

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arXiv2026

The unusually red delay spectrum of the low-mass black hole AGN NGC\,4051 as revealed by intensive continuum reverberation mapping with the Las Cumbres Observatory

We present a two-year optical reverberation mapping campaign of NGC 4051, an active galactic nucleus (AGN) hosting a low-mass black hole ($8\times10^5 M_\odot$), using daily observations in seven photometric bands from Las Cumbres Observatory augmented by archival data from Swift XRT and UVOT. The light curves show correlated variability with wavelength-dependent lags broadly consistent with the standard accretion disc scaling, $τ\propto λ^{4/3}$, and a pronounced u-band excess. However, the $i$ and $z_s$ lags are significantly larger than expected and cannot be explained by a combination of disc emission and diffuse continuum (DC) from the broad-line region (BLR), making NGC 4051 a notable lag-luminosity outlier. The spectral energy distribution (SED) of the variable AGN component is markedly redder than the canonical accretion disc prediction, $F_ν\propto ν^{1/3}$, typically observed in more massive systems. We explore two scenarios to account for the red UV-optical SED and the anomalously large $i$ and $z_s$ lags: (a) SMC-like dust reddening ($E(B-V)\sim0.18$) combined with optically thick emission from the inner edge of the dusty torus; and (b) a dominant diffuse continuum contribution. We discuss the implications of each scenario within a comprehensive multi-wavelength framework.

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arXiv2026

The Host Galaxies of Active Galactic Nuclei with Direct Black Hole Mass Measurements

Reverberation mapping (RM) determines the mass of black holes (BH) in active galactic nuclei (AGNs) by resolving the BH gravitational sphere of influence in the time domain. Recent RM campaigns yielded direct BH masses through dynamical modeling for a sample of 32 objects, spanning a wide range of AGN luminosities and BH masses. In addition, accurate BH masses have been determined by spatially resolving the broad-line region with GRAVITY for a handful of AGNs. Here, we present a detailed analysis of Hubble Space Telescope images using surface-brightness profile fitting with state-of-the-art programs. We derive AGN luminosity and host-galaxy properties, such as radii and luminosities for spheroid, disk, and bar (if present). The spheroid effective radii were used to measure stellar velocity dispersion from integral-field spectroscopy. Since the BH masses of our sample do not depend on any assumption of the virial factor needed in single-epoch spectroscopic mass estimates, we can show that the resulting scaling relations between the mass of the supermassive BHs and their host galaxies match those of quiescent galaxies, naturally extending to lower masses in these (predominantly) spiral galaxies. We find that the inner AGN orientation, as traced by the broad-line region inclination angle, is uncorrelated with the host-galaxy disk. Our sample has the most direct and accurate MBH measurements of any AGN sample and provides a fundamental local benchmark for studies of the evolution of massive black holes and their host galaxies across cosmic time.

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arXiv2026

A Phenomenological Study of the Accretion Disk in the Super-Eddington AGN I Zw 1

The structure of the accretion disk in AGN is still an unsolved question, especially how it may change with Eddington ratio. Here we examine the accretion disk in the super-Eddington AGN I Zw 1 using reverberation mapping of the optical continuum. We use three years of optical monitoring with Las Cumbres Observatory at sub-day cadence in $uBgVriz_s$. The lag-wavelength spectrum, calculated using the cross correlation method and PyROA, shows a $u$-band excess. PyROA lags are equally well fitted with a thin and slim disk profile. The UV/optical AGN spectral energy distribution is consistent with a thin disk. The disk size at 4495 Å for a thin disk model is $4.23\pm0.24\:\mathrm{ld}$ and for a slim disk model is $1.71\pm0.09\:\mathrm{ld}$, larger by a factor of $2-4$ than the fiducial disk size of $1.07\pm0.15\:\mathrm{ld}$ as determined using the Eddington ratio. We find evidence of different size scales probed with different variability timescales. Lags evaluated at longer variability timescales increase as do frequency-resolved lags at low frequencies, which we interpret as an additional secondary reprocessor at large radii consistent with the broad-line region (BLR) in I Zw 1. The high frequency lags, predicted well with just a disk, are fit with a thin disk profile and a size of $0.61\pm0.37\:\mathrm{ld}$. This indicates that the actual disk size may be on the order of the fiducial size. We also collate the most extensive set of directly measured internal sizes of an AGN, from optical to mid-infrared with reverberation mapping and optical interferometry. Assuming that the disk is indeed the fiducial size, these show little evidence that the accretion disk extends into the BLR significantly, tentatively disfavouring the failed radiatively accelerated dust driven outflow BLR formation model.

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arXiv2025

A close look at the black hole masses and hot dusty toruses of the first quasars with MIRI-MRS

The presence of supermassive black holes (SMBHs, $M_\text{BH}\sim10^9 M_\odot$) at $z>7$ remains a puzzle. While their existence appears to require exotic formation or growth processes, it is possible that BH mass estimates are incorrect due to differences from the low-$z$ quasars where BH mass scaling relations are calibrated. In this work, we employ JWST MIRI-MRS spectroscopy to measure the rest-frame optical/IR properties of the four highest-redshift known luminous type-1 quasars at $7.08\leq z<7.64$. We use three new broad lines to measure updated BH masses, H$α$, Pa$α$ and Pa$β$, finding them to be in the range $(4-15)\cdot10^8 M_\odot$. Our black hole mass estimates from all tracers agree with each other and with previous, less accurate, ground-based measurements based on MgII. The flux ratios of the H lines deviate from expectations for case A and B recombination in the same way as in $z<3$ quasars, indicating similar physical conditions in the Broad Line Region. Rest-frame near-IR continuum emission from a hot dusty torus surrounding the accretion disc is unambiguously detected in all four objects. We model the emission with SKIRTOR and constrain the inclination (face-on) and the opening angle ($θ=40-60^\circ$) of the tori. These constraints are consistent for the four objects and with expectations from luminous quasars. We estimate a total dust mass $(1-4)\cdot10^6 M_\odot$ in the tori, corresponding to $(0.2-7)\%$ of the total dust in the quasar host galaxies. Given observed accretion rates, these SMBHs will deplete their tori in only $\sim5$ Myr. Overall, we confirm that $z>7$ SMBHs in quasars could not have grown from stellar-remnant BHs if the radiative efficiency of accretion is $10\%$. We also find no evidence that inferred BH masses and accretion processes in $z>7$ quasars differ significantly from their near-identical counterparts at $z<3$.

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arXiv2025

AGN STORM 2. XI. Spectroscopic reverberation mapping of the hot dust in Mrk 817

The AGN Space Telescope and Optical Reverberation Mapping 2 (STORM 2) campaign targeted Mrk 817 with intensive multi-wavelength monitoring and found its soft X-ray emission to be strongly absorbed. We present results from 157 near-IR spectra with an average cadence of a few days. Whereas the hot dust reverberation signal as tracked by the continuum flux does not have a clear response, we recover a dust reverberation radius of $\sim 90$ light-days from the blackbody dust temperature light-curve. This radius is consistent with previous photometric reverberation mapping results when Mrk 817 was in an unobscured state. The heating/cooling process we observe indicates that the inner limit of the dusty torus is set by a process other than sublimation, rendering it a luminosity-invariant `dusty wall' of a carbonaceous composition. Assuming thermal equilibrium for dust optically thick to the incident radiation, we derive a luminosity of $\sim 6 \times 10^{44}$ erg s$^{-1}$ for the source heating it. This luminosity is similar to that of the obscured spectral energy distribution, assuming a disk with an Eddington accretion rate of $\dot{m} \sim 0.2$. Alternatively, the dust is illuminated by an unobscured lower luminosity disk with $\dot{m} \sim 0.1$, which permits the UV/optical continuum lags in the high-obscuration state to be dominated by diffuse emission from the broad-line region. Finally, we find hot dust extended on scales $> 140-350$ pc, associated with the rotating disk of ionised gas we observe in spatially-resolved [SIII] $λ9531$ images. Its likely origin is in the compact bulge of the barred spiral host galaxy, where it is heated by a nuclear starburst.

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arXiv2025

A Little Red Dot at $\mathbf{z=7.3}$ within a Large Galaxy Overdensity

The nature of "Little Red Dots" and their relation to other forms of accreting supermassive black holes remain an open question. Here we report the discovery of a Little Red Dot at $z=7.3$. It is attenuated by moderate amounts of dust, $A_V = {2.79}\,\textrm{mag}$, with an intrinsic bolometric luminosity of $10^{46.6}\,\textrm{erg}\,\textrm{s}^{-1}$ and a SMBH mass of $5\times10^8\,\textrm{M}_\odot$. Most notably, this object is embedded in an overdensity of eight nearby galaxies, allowing us to calculate a spectroscopic estimate of the clustering of galaxies around Little Red Dots. We find a Little Red Dot-galaxy cross-correlation length of $r_0\!=\!8\pm2\,\textrm{h}^{-1}\,\textrm{cMpc}$, comparable to that of $z\!\sim\!6$ UV-luminous quasars. The resulting estimate of their minimum dark matter halo mass of $\log_{10}(M_{\textrm{halo, min}}/\textrm{M}_{\odot})= 12.0_{-1.0}^{+0.8}$ indicates that nearly all halos above this mass must host actively accreting SMBHs at $z\approx7$, in strong contrast with the far smaller duty cycle of luminous quasars ($<1\%$). Our results, taken at face value, motivate a picture in which SMBHs in Little Red Dot phases could serve as the obscured precursors of UV-luminous quasars, which provides a natural explanation for the short UV-luminous lifetimes inferred from both quasar clustering and quasar proximity zones.

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arXiv2025

Spatially Resolved [O III] Emission Line Kinematics of Reverberation-Mapped AGNs with the Keck Cosmic Web Imager

We present optical integral-field spectroscopic data of ten nearby ($0.02\leq z \leq 0.05$) Seyfert 1 galaxies taken with the Keck Cosmic Web Imager (KCWI). We map the spatially resolved kinematics of the [O III] gas and stars, and investigate the alignments between their global kinematic position angles (PA). Large-scale gas motions are primarily dominated by rotation, and are kinematically aligned with the stars ($Δ\text{PA}\leq 30$ deg). However, eight galaxies exhibit non-rotational kinematic signatures (e.g., kinematic twists, possible outflows) in their ionized gas velocity fields near the nucleus. We compare aperture-wide measurements of the gas and stellar velocity dispersions ($σ_{\text{gas}}$ and $σ_\star$) to test the use of the width of the [O III] line core as a surrogate for $σ_\star$. Direct comparisons between $σ_{\text{gas}}$ and $σ_\star$ show that $σ_{\text{gas}}$ tends to underestimate $σ_\star$, and thus is not a reliable tracer of $σ_\star$ for our selected galaxies. We measure the extent of the narrow-line region (NLR) using several definitions, resulting in sizes of $\sim0.1$-$10$ kpc. For a given [O III] luminosity, our NLR sizes derived from the [O III]/H$β$ flux ratio or an [O III] isophotal radius are an order of magnitude larger than those measured from past imaging data.

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arXiv2025

Departures from Standard Disk Predictions in Intensive Ground-Based Monitoring of Three AGN

We present ground-based, multi-band light curves of the AGN Mrk~509, NGC\,4151, and NGC\,4593 obtained contemporaneously with \sw\, monitoring. We measure cross-correlation lags relative to \sw\, UVW2 (1928~Å) and test the standard prediction for disk reprocessing, which assumes a geometrically thin, optically thick accretion disk where continuum interband delays follow the relation $ τ(λ) \propto λ^{4/3} $. For Mrk~509 the 273-d \sw\, campaign gives well-defined lags that increase with wavelength as $τ(λ)\proptoλ^{2.17\pm0.2}$, steeper than the thin-disk prediction, and the optical lags are a factor of $\sim5$ longer than expected for a simple disk-reprocessing model. This ``disk-size discrepancy'' as well as excess lags in the $u$ and $r$ bands (which include the Balmer continuum and H$α$, respectively) suggest a mix of short lags from the disk and longer lags from nebular continuum originating in the broad-line region. The shorter \sw\, campaigns, 69~d on NGC\,4151 and 22~d on NGC\,4593, yield less well-defined, shorter lags $<2$~d. The NGC\,4593 lags are consistent with $τ(λ) \propto λ^{4/3}$ but with uncertainties too large for a strong test. For NGC\,4151 the \sw\, lags match $τ(λ) \propto λ^{4/3}$, with a small $U$-band excess, but the ground-based lags in the $r$, $i$, and $z$ bands are significantly shorter than the $B$ and $g$ lags, and also shorter than expected from the thin-disk prediction. The interpretation of this unusual lag spectrum is unclear. Overall these results indicate significant diversity in the $τ-λ$ relation across the optical/UV/NIR, which differs from the more homogeneous behavior seen in the \sw\, bands.

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arXiv2025

Optical and near-infrared spectroscopy of quasars at $z>6.5$: public data release and composite spectrum

We present optical and near-infrared (NIR) spectroscopic observations for a sample of $45$ quasars at $6.50 < z \leq 7.64$ with absolute magnitudes at $1450$ Å in the range $-28.82 \leq M_{1450} \leq -24.13$ and their composite spectrum. The median redshift and $M_{1450}$ of the quasars in the sample are $z_{\rm{median}}=6.71$ and $M_{1450,\rm{median}} \simeq -26.1$, respectively. The NIR spectra are taken with echelle spectrographs, complemented with additional data from optical long slit instruments, and then reduced consistently using the open-source Python-based spectroscopic data reduction pipeline PypeIt. The median of the mean signal-to-noise ratios per $110$ km s$^{-1}$ pixel in the J, H, and K band [median $\langle \rm{SNR}_λ \rangle$] is: median $\langle \rm{SNR}_{J} \rangle=9.7$, median $\langle \rm{SNR}_{H} \rangle=10.3$, and median $\langle \rm{SNR}_{K} \rangle=11.7$; demonstrating the good data quality. This work presents the largest medium/moderate-resolution sample of quasars at $z>6.5$ from ground-based instruments. Despite the diversity in instrumental setups and spectral quality, the data set is uniformly processed and well-characterized, making it ideally suited for several scientific goals, including the study of the quasar proximity zones and damping wings, the Ly$α$ forest, the intergalactic medium's metal content, as well as other properties such as the distribution of SMBH masses and Eddington ratios. Our composite spectrum is compared to others at both high and low-$z$ from the literature, showing differences in the strengths of many emission lines, probably due to differences in luminosity among the samples, but a consistent continuum slope, which proves that the same spectral features are preserved in quasars at different redshift ranges.

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arXiv2025

Seoul National University AGN Monitoring Project. V. Velocity-resolved H-beta Reverberation Mapping and Evidence of Kinematics Evolution

We present velocity-resolved reverberation lags of H-beta for 20 active galactic nuclei (AGNs) from the Seoul National University AGN Monitoring Project. We detect unambiguous velocity-resolved structures in 12 AGNs, among which eight objects exhibit symmetric structures, two objects show inflow-like characteristics, and two objects display outflow-like signatures. For two AGNs, we successfully measure the velocity-resolved lags in different years, revealing evidence of evolving broad-line region (BLR) kinematics. By combining our sample with the literature velocity-resolved lags, we find that the symmetric velocity-resolved lags are the most common (40%) type among this sample. The frequency of inflow kinematics is also notable (20%), while outflow kinematics are less common (11%). Our sample significantly expands the previous velocity-resolved reverberation mapping sample in the high-luminosity regime, enabling us to constrain BLR kinematics across a large dynamic range of luminosity.

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arXiv2025

Testing X-ray Reprocessing and Mapping the Soft Excess of NGC 7469 with NICER

We present an X-ray/UV reverberation analysis of NGC 7469 across 210 days, using daily NICER observations with contemporaneous monitoring by Swift UVOT+XRT. We model the X-ray spectrum with a power law continuum and a soft excess during each NICER epoch. These emission sources demonstrate correlated flux variability with a lag consistent with zero days. We find that the power law emission is consistent with a compact X-ray corona, and that the soft excess can be explainedby reflected coronal emission from the inner accretion disk. We test the relationship between changes in the flux of the X-ray corona and the UVW2 continuum, finding strong correlation and a negative X-ray lag of less than one day. This is consistent with a scenario in which the X-ray corona drives the UVW2 light curve through thermal reprocessing

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arXiv2024

A blazar in the epoch of reionization

Relativistic jets are thought to play a crucial role in the formation and evolution of massive galaxies and supermassive black holes. Blazars, which are quasars with jets aligned along our line of sight, provide insights into the jetted population and have been observed up to redshifts of z=6.1. Here, we report the discovery and multi-wavelength characterization of the blazar VLASS J041009.05-013919.88 at z=7 (Universe's age ~750 Myr), powered by a ~7x10^8 Msun black hole. The presence of this high-redshift blazar implies a large population of similar but unaligned jetted sources in the early Universe. Our findings suggest two possible scenarios: in one, the jet in J0410-0139 is intrinsically low-power but appears highly luminous due to relativistic beaming, suggesting that most UV-bright quasars at this redshift host jets. Alternatively, if J0410-0139 represents an intrinsically powerful radio source, there should be hundreds to thousands of radio-quiet quasars at z~7 with properties similar to J0410-0139, a prediction in tension with observed quasar densities based on their UV luminosity function. These results support the hypothesis that rapid black hole growth in the early Universe may be driven by jet-enhanced or obscured super-Eddington accretion, potentially playing a key role in forming massive black holes during the epoch of reionization.

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arXiv2024

Combining Direct Black Hole Mass Measurements and Spatially Resolved Stellar Kinematics to Calibrate the $M_{\rm BH}$-$σ_\star$ Relation of Active Galaxies

The origin of the tight scaling relation between the mass of supermassive black holes (SMBHs; $M_{\rm BH}$) and their host-galaxy properties remains unclear. Active galactic nuclei (AGNs) probe phases of ongoing SMBH growth and offer the only opportunity to measure $M_{\rm BH}$ beyond the local Universe. However, determining AGN host galaxy stellar velocity dispersion $σ_\star$, and their galaxy dynamical masses $M_{\rm dyn}$, is complicated by AGN contamination, aperture effects and different host galaxy morphologies. We select a sample of AGNs for which $M_{\rm BH}$ has been independently determined to high accuracy by state-of-the-art techniques: dynamical modeling of the reverberation signal and spatially resolving the broad-line region with VLTI/GRAVITY. Using IFU observations, we spatially map the host galaxy stellar kinematics across the galaxy and bulge effective radii. We find that that the dynamically hot component of galaxy disks correlates with $M_{\rm BH}$; however, the correlations are tightest for aperture-integrated $σ_\star$ measured across the bulge. Accounting for the different $M_{\rm BH}$ distributions, we demonstrate - for the first time - that AGNs follow the same $M_{\rm BH}$-$σ_\star$ and $M_{\rm BH}$-$M_{\rm bulge, dyn}$ relations as quiescent galaxies. We confirm that the classical approach of determining the virial factor as sample-average, yielding ${\rm log }f= 0.65 \pm 0.18$, is consistent with the average $f$ from individual measurements. The similarity between the underlying scaling relations of AGNs and quiescent galaxies implies that the current AGN phase is too short to have altered BH masses on a population level. These results strengthen the local calibration of $f$ for measuring single-epoch $M_{\rm BH}$ in the distant Universe.

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arXiv2024

AGN STORM 2: X. The origin of the interband continuum delays in Mrk 817

The local (z=0.0315) AGN Mrk 817, was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign AGN STORM 2. Here, we present a comprehensive analysis of the broad-band continuum variations using detailed modeling of the broad line region (BLR), several types of disk winds classified by their optical depth, and new numerical simulations. We find that diffuse continuum (DC) emission, with additional contributions from strong and broad emission lines, can explain the continuum lags observed in this source during high and low luminosity phases. Disk illumination by the variable X-ray corona contributes only a small fraction of the observed continuum lags. Our BLR models assume radiation pressure-confined clouds distributed over a distance of 2-122 light days. We present calculated mean-emissivity radii of many emission lines, and DC emission, and suggest a simple, transfer-function-dependent method that ties them to cross-correlation lag determinations. We do not find clear indications for large optical depth winds but identify the signature of lower column density winds. In particular, we associate the shortest observed continuum lags with a combination of tau(1 Ryd) approx. 2 wind and a partly shielded BLR. Even smaller optical depth winds may be associated with X-ray absorption features and with noticeable variations in the width and lags of several high ionization lines like HeII and CIV. Finally, we demonstrate the effect of torus dust emission on the observed lags in the i and z bands.

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