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We present the second iteration of the caramel-gas code, an empirical model of the broad-line region (BLR) gas density field. Building on the initial development and testing of caramel-gas , we expand the meaning of the model parameter α , which initially represented only the power-law index of the dependency of emissivity on radial distance. In this work, we test a more generalized radial power-law index, α , that also includes a description of the effective emitting size(s) of the BLR structure as a function of radial distance. We select a sample of 10 active galactic nuclei (AGN) from three different Lick AGN Monitoring Project campaigns to further validate the caramel-gas code and test the generalized radial power-law index, α . Our results confirm that the caramel-gas results are in general agreement with the published results determined using the original caramel code, further demonstrating that our forward modeling method is robust. We find that a positive radial power-law index is generally favored and propose three possible scenarios: (i) the BLR structure has increasing effective emitting size(s) at larger radial distances from the central source, (ii) emission is concentrated at the outer edges of the BLR, and (iii) stronger theoretical assumptions are needed to break the degeneracies inherent to the interpretation of reverberation mapping data in terms of underlying gas properties.

We present the main results from a long-term reverberation mapping campaign carried out for the Seoul National University AGN Monitoring Project (SAMP). High-quality data were obtained during 2015–2021 for 32 luminous active galactic nuclei (AGNs; i.e., continuum luminosity in the range of 10 ^44–46 erg s ^−1 ) at a regular cadence, of 20–30 days for spectroscopy and 3–5 days for photometry. We obtain time lag measurements between the variability in the H β emission and the continuum for 32 AGNs; 25 of those have the best lag measurements based on our quality assessment, examining correlation strength and the posterior lag distribution. Our study significantly increases the current sample of reverberation-mapped AGNs, particularly at the moderate-to-high-luminosity end. Combining our results with literature measurements, we derive an H β broadline region size–luminosity relation with a shallower slope than reported in the literature. For a given luminosity, most of our measured lags are shorter than the expectations, implying that single-epoch black hole mass estimators based on previous calibrations could suffer large systematic uncertainties.

The broad-line region (BLR) size–luminosity relation has paramount importance for estimating the mass of black holes in active galactic nuclei (AGNs). Traditionally, the size of the H β BLR is often estimated from the optical continuum luminosity at 5100 Å, while the size of the H α BLR and its correlation with the luminosity is much less constrained. As a part of the Seoul National University AGN Monitoring Project, which provides 6 yr photometric and spectroscopic monitoring data, we present our measurements of the H α lags of high-luminosity AGNs. Combined with the measurements for 42 AGNs from the literature, we derive the size–luminosity relations of the H α BLR against the broad H α and 5100 Å continuum luminosities. We find the slope of the relations to be 0.61 ± 0.04 and 0.59 ± 0.04, respectively, which are consistent with the H β size–luminosity relation. Moreover, we find a linear relation between the 5100 Å continuum luminosity and the broad H α luminosity across 7 orders of magnitude. Using these results, we propose a new virial mass estimator based on the H α broad emission line, finding that the previous mass estimates based on scaling relations in the literature are overestimated by up to 0.7 dex at masses lower than 10 ^7 M _⊙ .

Low-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 Sloan Digital Sky Survey (SDSS)-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45%–64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27%−41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations

We combine our dynamical modeling black-hole mass measurements from the Lick AGN Monitoring Project 2016 sample with measured cross-correlation time lags and line widths to recover individual scale factors, f , used in traditional reverberation-mapping analyses. We extend our sample by including prior results from Code for AGN Reverberation and Modeling of Emission Lines ( caramel ) studies that have utilized our methods. Aiming to improve the precision of black-hole mass estimates, as well as uncover any regularities in the behavior of the broad-line region (BLR), we search for correlations between f and other AGN/BLR parameters. We find (i) evidence for a correlation between the virial coefficient ${\mathrm{log}}_{10}({f}_{\mathrm{mean},\sigma })$ and black-hole mass, (ii) marginal evidence for a similar correlation between ${\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma })$ and black-hole mass, (iii) marginal evidence for an anticorrelation of BLR disk thickness with ${\mathrm{log}}_{10}({f}_{\mathrm{mean},\mathrm{FWHM}})$ and ${\mathrm{log}}_{10}({f}_{\mathrm{rms},\mathrm{FWHM}})$ , and (iv) marginal evidence for an anticorrelation of inclination angle with ${\mathrm{log}}_{10}({f}_{\mathrm{mean},\mathrm{FWHM}})$ , ${\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma })$ , and ${\mathrm{log}}_{10}({f}_{\mathrm{mean},\sigma })$ . Last, we find marginal evidence for a correlation between line-profile shape, when using the root-mean-square spectrum, ${\mathrm{log}}_{10}{(\mathrm{FWHM}/\sigma )}_{\mathrm{rms}}$ , and the virial coefficient, ${\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma })$ , and investigate how BLR properties might be related to line-profile shape using caramel models.

Correlations between the mass of a supermassive black hole (SMBH) and the properties of its host galaxy (e.g., total stellar mass M*, luminosity Lhost) suggest an evolutionary connection. A powerful test of a coevolution scenario is to measure the relations –Lhost and –M* at high redshift and compare with local estimates. For this purpose, we acquired Hubble Space Telescope (HST) imaging with WFC3 of 32 X-ray-selected broad-line (type 1) active galactic nuclei at 1.2 < z < 1.7 in deep survey fields. By applying state-of-the-art tools to decompose the HST images including available ACS data, we measured the host galaxy luminosity and stellar mass along with other properties through the two-dimensional model fitting. The black hole mass () was determined using the broad Hα line, detected in the near-infrared with the Subaru Fiber Multi-Object Spectrograph, which potentially minimizes systematic effects using other indicators. We find that the observed ratio of to total M* is 2.7× larger at z ∼ 1.5 than in the local universe, while the scatter is equivalent between the two epochs. A nonevolving mass ratio is consistent with the data at the 2σ–3σ confidence level when accounting for selection effects (estimated using two independent and complementary methods) and their uncertainties. The relationship between and host galaxy total luminosity paints a similar picture. Therefore, our results cannot distinguish whether SMBHs and their total host stellar mass and luminosity proceed in lockstep or whether the growth of the former somewhat overshoots the latter, given the uncertainties. Based on a statistical estimate of the bulge-to-total mass fraction, the ratio /M*,bulge is offset from the local value by a factor of ∼7, which is significant even accounting for selection effects. Taken together, these observations are consistent with a scenario in which stellar mass is subsequently transferred from an angular momentum–supported component of the galaxy to a pressure-supported one through secular processes or minor mergers at a faster rate than mass accretion onto the SMBH. [ABSTRACT FROM AUTHOR]

We present an unprecedented view of the morphology and kinematics of the extended narrow-line region (ENLR) and molecular gas around the prototypical hyperluminous quasar 3C 273 (Lbol ∼ 1047 erg s−1 at z = 0.158) based on VLT-MUSE optical 3D spectroscopy and ALMA observations. We find the following: (1) the ENLR size of 12.1 ± 0.2 kpc implies a smooth continuation of the size–luminosity relation out to large radii or a much larger break radius as previously proposed. (2) The kinematically disturbed ionized gas with line splits reaching 1000 km s−1 out to 6.1 ± 1.5 kpc is aligned along the jet axis. (3) The extreme line broadening on kiloparsec scales is caused by the spatial and spectral blending of many distinct gas clouds separated on subarcsecond scales by different line-of-sight (LOS) velocities. The ENLR velocity field combined with the known jet orientation rules out a simple scenario of a radiatively driven radial expansion of the outflow. Instead, we propose that a pressurized expanding hot gas cocoon created by the radio jet is impacting on an inclined gas disk, leading to transverse and/or backflow motion with respect to our LOS. The molecular gas morphology may be explained by either a density wave at the front of the outflow expanding along the jet direction as predicted by the positive feedback scenario or the cold gas may be trapped in a stellar overdensity caused by a recent merger event. Using 3C 273 as a template for observations of high-redshift hyperluminous quasars reveals that large-scale ENLRs and kiloparsec-scale outflows may often be missed, due to the brightness of the nuclei and the limited sensitivity of current near-IR instrumentation. [ABSTRACT FROM AUTHOR]

In Spring 2011, the Lick AGN Monitoring Project observed a sample of 15 bright, nearby Seyfert 1 galaxies in the V band as part of a reverberation mapping campaign. The observations were taken at six ground-based telescopes, including the West Mountain Observatory 0.91 m telescope, the 0.76 m Katzman Automatic Imaging Telescope, 0.6 m Super-LOTIS at Kitt Peak, the Palomar 60 inch telescope, and the 2 m Faulkes telescopes North and South. The V-band light curves measure the continuum variability of our sample of Seyferts on an almost daily cadence for 2–3 months. We use image-subtraction software to isolate the variability of the Seyfert nucleus from the constant V-band flux of the host galaxy for the most promising targets, and we adopt standard aperture photometry techniques for the targets with smaller levels of variability. These V-band light curves will be used, with measurements of the broad emission line flux, to measure supermassive black hole masses and to constrain the geometry and dynamics of the broad-line region through dynamical modeling techniques. [ABSTRACT FROM AUTHOR]

NGC 1275 is one of the most conspicuous active galactic nuclei (AGN) in the local universe. The radio jet currently emits a flux density of ∼10 Jy at ∼1 mm wavelengths, down from the historic high of ∼65 Jy in 1980. Yet, the nature of the AGN in NGC 1275 is still controversial. It has been debated whether this is a broad emission line (BEL) Seyfert galaxy, an obscured Seyfert galaxy, a narrow line radio galaxy, or a BL Lac object. We clearly demonstrate a persistent Hβ BEL over the last 35 yr with a full width at half maximum (FWHM) of 4150–6000 km s−1. We also find a prominent Pα BEL (FWHM ≈ 4770 km s−1) and a weak C iv BEL (FWHM ≈ 4000 km s−1), Hβ/C iv ≈ 2. A far-UV Hubble Space Telescope observation during suppressed jet activity reveals a low luminosity continuum. The Hβ BEL luminosity is typical of broad line Seyfert galaxies with similar far-UV luminosity. X-ray observations indicate a softer ionizing continuum than what would be expected for a broad line Seyfert galaxy with similar far-UV luminosity. This is the opposite of the expectation of advection-dominated accretion. The AGN continuum appears to be thermal emission from a low luminosity, optically thick, accretion flow with a low Eddington ratio, ∼0.0001. The soft, weak, ionizing continuum is consistent with the relatively weak C iv BEL. Evidence that the BEL luminosity is correlated with the jet millimeter-wave luminosity is presented. It appears that the accretion rate regulates jet power. [ABSTRACT FROM AUTHOR]

We present models of the Hβ-emitting broad-line region (BLR) in seven Seyfert 1 galaxies from the Lick AGN Monitoring Project 2011 sample, drawing inferences on the BLR structure and dynamics as well as the mass of the central supermassive black hole. We find that the BLR is generally a thick disk, viewed close to face-on, with preferential emission back toward the ionizing source. The dynamics in our sample range from near-circular elliptical orbits to inflowing or outflowing trajectories. We measure black hole masses of for PG 1310−108, for Mrk 50, for Mrk 141, for Mrk 279, for Mrk 1511, for NGC 4593, and for Zw 229−015. We use these black hole mass measurements along with cross-correlation time lags and line widths to recover the scale factor f used in traditional reverberation mapping measurements. Combining our results with other studies that use this modeling technique, which brings our sample size to 16, we calculate a scale factor that can be used for measuring black hole masses in other reverberation mapping campaigns. When using the root-mean-square (rms) spectrum and using the line dispersion to measure the line width, we find pred = 0.57 ± 0.19. Finally, we search for correlations between f and other AGN and BLR parameters and find marginal evidence that f is correlated with MBH and the BLR inclination angle, but no significant evidence of a correlation with the AGN luminosity or Eddington ratio. [ABSTRACT FROM AUTHOR]

We present single-epoch black hole mass () calibrations based on the rest-frame ultraviolet (UV) and optical measurements of Mg ii 2798 Å and Hβ 4861 Å lines and the active galactic nucleus (AGN) continuum, using a sample of 52 moderate-luminosity AGNs at z ∼ 0.4 and z ∼ 0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference based on the line dispersion of Hβ and continuum luminosity at 5100 Å, we calibrate the UV and optical mass estimators by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show a systematic trend with Eddington ratio, FWHM of Hβ, Fe ii strength, or UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg ii-based and Hβ-based masses with the L3000/L5100 ratio, we provide a correction term as a function of the spectral index as ΔC = 0.24 (1 + αλ) + 0.17, which can be added to the Mg ii-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show >∼0.2 dex intrinsic scatter with respect to the Hβ-based , suggesting that the UV-based mass has an additional uncertainty of ∼0.2 dex, even if high-quality rest-frame UV spectra are available. [ABSTRACT FROM AUTHOR]

The Type Ia supernova (SN Ia) 2016coj in NGC 4125 (redshift z = 0.00452 ± 0.00006) was discovered by the Lick Observatory Supernova Search 4.9 days after the fitted first-light time (FFLT; 11.1 days before B-band maximum). Our first detection (prediscovery) is merely 0.6 ± 0.5 days after the FFLT, making SN 2016coj one of the earliest known detections of an SN Ia. A spectrum was taken only 3.7 hr after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We performed high-quality photometry, low- and high-resolution spectroscopy, and spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN Ia, but the velocity of Si ii λ6355 around peak brightness (∼12,600 ) is a bit higher than that of typical normal SNe. The Si ii λ6355 velocity evolution can be well fit by a broken-power-law function for up to a month after the FFLT. SN 2016coj has a normal peak luminosity ( mag), and it reaches a B-band maximum ∼16.0 days after the FFLT. We estimate there to be low host-galaxy extinction based on the absence of Na i D absorption lines in our low- and high-resolution spectra. The spectropolarimetric data exhibit weak polarization in the continuum, but the Si ii line polarization is quite strong (∼0.9% ± 0.1%) at peak brightness. [ABSTRACT FROM AUTHOR]

We provide an updated calibration of C iv broad emission line–based single-epoch (SE) black hole (BH) mass estimators for active galactic nuclei (AGNs) using new data for six reverberation-mapped AGNs at redshift with BH masses (bolometric luminosities) in the range ( erg s−1). New rest-frame UV-to-optical spectra covering 1150–5700 Å for the six AGNs were obtained with the Hubble Space Telescope (HST). Multicomponent spectral decompositions of the HST spectra were used to measure SE emission-line widths for the C iv, Mg ii, and Hβ lines, as well as continuum luminosities in the spectral region around each line. We combine the new data with similar measurements for a previous archival sample of 25 AGNs to derive the most consistent and accurate calibrations of the C iv-based SE BH mass estimators against the Hβ reverberation-based masses, using three different measures of broad-line width: full width at half maximum (FWHM), line dispersion (), and mean absolute deviation (MAD). The newly expanded sample at redshift covers a dynamic range in BH mass (bolometric luminosity) of ( erg s−1 ), and we derive the new C iv-based mass estimators using a Bayesian linear regression analysis over this range. We generally recommend the use of or MAD rather than FWHM to obtain a less biased velocity measurement of the C iv emission line, because its narrow-line component contribution is difficult to decompose from the broad-line profile. [ABSTRACT FROM AUTHOR]

We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Qion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Qion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2 × 104 yr before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission, morphologically suggestive of outflow, are common, their kinematic structure shows some to be in regular rotation. UGC 7342 exhibits local signatures of outflows <300 km s−1, largely associated with very diffuse emission, and possibly entraining gas in one of the clouds seen in Hubble Space Telescope images. Only in the Teacup AGN do we see outflow signatures of the order of 1000 km s−1. In contrast to the extended emission regions around many radio-loud AGNs, the clouds around these fading AGNs consist largely of tidal debris being externally illuminated but not displaced by AGN outflows. [ABSTRACT FROM AUTHOR]

A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses MBH > 107M⊙ was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between MBH and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate MBH, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (∼66%) of the objects, resulting in a Seyfert-type change for ∼38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hβ line virtually disappears in 3/102 (∼3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study provides statistical information on the frequency of Hβ line variability in a sample of low-redshift Seyfert galaxies. [ABSTRACT FROM AUTHOR]

We create a baseline of the black hole (BH) mass ()—stellar-velocity dispersion (σ) relation for active galaxies, using a sample of 66 local () Seyfert-1 galaxies, selected from the Sloan Digital Sky Survey (SDSS). Analysis of SDSS images yields AGN luminosities free of host-galaxy contamination, and morphological classification. 51/66 galaxies have spiral morphology. Out of these, 28 bulges have Sérsic index and are considered candidate pseudo-bulges, with eight being definite pseudo-bulges based on multiple classification criteria met. Only 4/66 galaxies show signs of interaction/merging. High signal-to-noise ratio Keck spectra provide the width of the broad Hβ emission line free of Fe ii emission and stellar absorption. AGN luminosity and Hβ line widths are used to estimate . The Keck-based spatially resolved kinematics is used to determine stellar-velocity dispersion within the spheroid effective radius (). We find that σ can vary on average by up to 40% across definitions commonly used in the literature, emphasizing the importance of using self-consistent definitions in comparisons and evolutionary studies. The –σ relation for our Seyfert-1 galaxy sample has the same intercept and scatter as that of reverberation-mapped AGNs as well as that of quiescent galaxies, consistent with the hypothesis that our single epoch estimator and sample selection function do not introduce significant biases. Barred galaxies, merging galaxies, and those hosting pseudo-bulges do not represent outliers in the –σ relation. This is in contrast with previous work, although no firm conclusion can be drawn on this matter due to the small sample size and limited resolution of the SDSS images. [ABSTRACT FROM AUTHOR]