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The changes of broad emission lines should be a crucial issue in understanding the physical properties of changing-look active galactic nuclei (CL-AGNs). Here we present the results of an intensive and homogeneous 6 month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018–2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest-frame time lags of Hα and Hβ are and days, respectively. From an rms Hβ line dispersion of σline = 1713.3 ± 46.7 km s−1 and a virial factor of fσ = 5.5, the central black hole mass of NGC 3516 is estimated to be , which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase toward negative velocity for both Hα and Hβ. The velocity-resolved RM of Hα is done for the first time. These RM results are consistent with other observations before the spectral-type change, indicating a basically constant broad-line region structure during the CL process. The CL model of changes of accretion rate seems to be favored by long-term Hβ variability and RM observations of NGC 3516. [ABSTRACT FROM AUTHOR]

We report on the results of a new spectroscopic monitoring campaign of the quasar PG 0026+129 at the Calar Alto Observatory 2.2 m telescope from 2017 July to 2020 February. Significant variations in the fluxes of the continuum and broad emission lines, including Hβ and He ii , were observed in the first and third years, and clear time lags between them are measured. The broad Hβ line profile consists of two Gaussian components: an intermediate-width H with an FWHM of 1964 ± 18 and another very broad H with an FWHM of 7570 ± 83. H has long time lags of ∼40–60 days in the rest frame, while H shows nearly zero time delay with respect to the optical continuum at 5100 Å. The velocity-resolved delays show consistent results: lags of ∼30–50 days at the core of the broad Hβ line and roughly zero lags at the wings. H has a redshift of ∼400 , which seems to be stable for nearly 30 yr by comparing with archived spectra, and may originate from an infall. The rms spectrum of H shows a double-peaked profile with brighter blue peak and extended red wing in the first year, which matches the signature of a thin disk. Both the double-peaked profile and the near-zero lag suggest that H comes from a region associated with the part of the accretion disk that emits the optical continuum. Adopting the FWHM (in the rms spectrum) and the time lag measured for the total Hβ line, and a virial factor of 1.5, we obtain a virial mass of for the central black hole in this quasar. [ABSTRACT FROM AUTHOR]

We report first results from a large project to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). Such objects may be different from other AGNs in being powered by slim accretion disks and showing saturated accretion luminosities, but both are not yet fully understood. The results are part of a large reverberation mapping (RM) campaign using the 2.4 m Shangri-La telescope at the Yunnan Observatory in China. The goals are to investigate the gas distribution near the BH and the properties of the central accretion disks, to measure BH mass and Eddington ratios, and to test the feasibility of using such objects as a new type of cosmological candles. The paper presents results for three objects, Mrk 335, Mrk 142, and IRAS F12397+3333, with Hβ time lags relative to the 5100 Å continuum of , and days, respectively. The corresponding BH masses are , , and , and the lower limits on the Eddington ratios are 0.6, 2.3, and 4.6 for the minimal radiative efficiency of 0.038. Mrk 142 and IRAS F12397+333 (extinction corrected) clearly deviate from the currently known relation between Hβ lag and continuum luminosity. The three Eddington ratios are beyond the values expected in thin accretion disks and two of them are the largest measured so far among objects with RM-based BH masses. We briefly discuss implications for slim disks, BH growth, and cosmology. [ABSTRACT FROM AUTHOR]

We performed a rigorous reverberation-mapping analysis of the broad-line region (BLR) in a highly accreting (L / L Edd = 0.74–3.4) active galactic nucleus, Markarian 142 (Mrk 142), for the first time using concurrent observations of the inner accretion disk and the BLR to determine a time lag for the H β λ 4861 emission relative to the ultraviolet (UV) continuum variations. We used continuum data taken with the Niel Gehrels Swift Observatory in the UVW 2 band, and the Las Cumbres Observatory, Dan Zowada Memorial Observatory, and Liverpool Telescope in the g band, as part of the broader Mrk 142 multiwavelength monitoring campaign in 2019. We obtained new spectroscopic observations covering the H β broad emission line in the optical from the Gemini North Telescope and the Lijiang 2.4 m Telescope for a total of 102 epochs (over a period of 8 months) contemporaneous to the continuum data. Our primary result states a UV-to-H β time lag of 8.68 − 0.72 + 0.75 days in Mrk 142 obtained from light-curve analysis with a Python-based running optimal average algorithm. We placed our new measurements for Mrk 142 on the optical and UV radius–luminosity relations for NGC 5548 to understand the nature of the continuum driver. The positions of Mrk 142 on the scaling relations suggest that UV is closer to the "true" driving continuum than the optical. Furthermore, we obtain log (M • / M ⊙) = 6.32 ± 0.29 assuming UV as the primary driving continuum. [ABSTRACT FROM AUTHOR]

We report strong and rapid X-ray variability found from the super-Eddington accreting quasar SDSS J081456.10+532533.5 at z = 0.1197. It has a black hole mass of 2.7 × 107 M ⊙ and a dimensionless accretion rate of ≈4 measured from reverberation-mapping observations. It showed weak X-ray emission in the 2021 February Chandra observation, with the 2 keV flux density being 9.6 − 4.6 + 11.6 times lower compared to an archival Swift observation. The 2 keV flux density is also 11.7 − 6.3 + 9.6 times weaker compared to the expectation from its optical/UV emission. In a follow-up XMM-Newton observation 32 days later, the 2 keV flux density increased by a factor of 5.3 − 2.4 + 6.4 , and the spectra are best described by a power law modified with partial-covering absorption; the absorption-corrected intrinsic continuum is at a nominal flux level. Nearly simultaneous optical spectra reveal no variability, and there is only mild long-term optical/infrared variability from archival data (with a maximum variability amplitude of ≈50%). We interpret the X-ray variability with an obscuration scenario, where the intrinsic X-ray continuum does not vary but the absorber has a variable column density and covering factor along the line of sight. The absorber is likely the small-scale clumpy accretion wind that has been proposed to be responsible for similar X-ray variability in other super-Eddington accreting quasars. [ABSTRACT FROM AUTHOR]

We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500-5500 Å. The sample is explicitly designed to mitigate spurious effects on SPCA induced by Fe II velocity shifts. We improve the algorithm of SPCA in the literature and introduce a new quantity, the fractional-contribution spectrum, that effectively identifies the emission features encoded in each eigenspectrum. The first eigenspectrum clearly records the power-law continuum and very broad Balmer emission lines. Narrow emission lines dominate the second eigenspectrum. The third eigenspectrum represents the Fe II emission and a component of the Balmer lines with kinematically similar intermediate-velocity widths. Correlations between the weights of the eigenspectra and parametric measurements of line strength and continuum slope confirm the above interpretation for the eigenspectra. Monte Carlo simulations demonstrate the validity of our method to recognize cross talk in SPCA and firmly rule out a single-component model for broad Hβ. We also present the results of SPCA for four other samples that contain quasars in bins of larger Fe II velocity shift; similar eigenspectra are obtained. We propose that the Hβ-emitting region has two kinematically distinct components: one with very large velocities whose strength correlates with the continuum shape and another with more modest, intermediate velocities that is closely coupled to the gas that gives rise to Fe II emission. [ABSTRACT FROM AUTHOR]

The quasar 3C 273 has been observed with infrared spectroastrometry (SA) of the broad Pa α line and optical reverberation mapping (RM) of the broad H β line. SA delivers information about the angular size and structure of the Pa α broad-line region (BLR), while RM delivers information about the physical size and structure of the H β BLR. Based on the fact that the two BLRs share the mass of the supermassive black hole (SMBH) and viewing inclination, a combination of SA and velocity-resolved RM (SARM) thereby allows us to simultaneously determine the SMBH mass and geometric distance through dynamically modeling the two BLRs. We construct a suite of dynamical models with different geometric configurations and apply a Bayesian approach to obtain the parameter inferences. Overall the obtained masses and distances are insensitive to specific BLR configurations but more or less depend on parameterizations of the vertical distributions. The most probable model, chosen in light of the Bayes factor, yields an angular-size distance log (D A / Mpc) = 2.83 âˆ' 0.28 + 0.32 and an SMBH mass log (M • / M ⊙) = 9.06 âˆ' 0.27 + 0.21 , which agree with the relationships between SMBH masses and bulge properties. The BLRs have an inclination of 5 âˆ' 1 + 1 degrees, consistent with that of the large-scale jet in 3C 273. Our approach reinforces the capability of SARM analysis to measure SMBH masses and distances of active galactic nuclei and quasars even though SA and RM observations are undertaken with different emission lines and/or in different periods. [ABSTRACT FROM AUTHOR]

NGC 2617 attracted a lot of attention after the detection of changes in its spectral type; the geometry and kinematics of the broad-line region (BLR) are still ambiguous. In this paper, we present the high cadence (∼2 days) reverberation mapping campaign of NGC 2617 from 2019 October to 2020 May undertaken at the Lijiang 2.4 m telescope. For the first time, the velocity-resolved reverberation signature of the object was successfully detected. Both Hα and Hβ show an asymmetrical profile with a peak in the velocity-resolved time lags. For both of the lines, the lag of the line core is longer than those of the relevant wings, and the peak of the velocity-resolved lags is slightly blueshifted. These characteristics are not consistent with the theoretical prediction of the inflow, outflow or Keplerian disk model. Our observations give the time lags of Hα, Hβ, Hγ, and He i , with a ratio of τHα: τHβ: τHγ: τHe I = 1.27:1.00:0.89:0.20, which indicates a stratified structure in the BLR of the object. It is the first time that the lags of Hα and He i are obtained. Assuming a virial factor of f = 5.5 for the dispersion width of the line, the masses of the black holes derived from Hα and Hβ are and , respectively. Our observed results indicate the complexity of the BLR of NGC 2617. [ABSTRACT FROM AUTHOR]

We report the results of reverberation mapping of three bright Seyfert galaxies, Mrk 79, NGC 3227, and Mrk 841, from a campaign conducted from 2016 December to 2017 May with the Wyoming Infrared Observatory (WIRO) 2.3 m telescope. All three of these targets have shown asymmetric broad Hβ emission lines in the past, although their emission lines were relatively symmetric during our observations. We measured Hβ time lags for all three targets and estimated masses of their black holes—for the first time in the case of Mrk 841. For Mrk 79 and NGC 3227, the data are of sufficient quality to resolve distinct time lags as a function of velocity and to compute two-dimensional velocity-delay maps. Mrk 79 shows smaller time lags for high-velocity gas, but the distribution is not symmetric, and its complex velocity-delay map could result from the combination of both inflowing and outflowing Hβ emitting disks that may be part of a single larger structure. NGC 3227 shows the largest time lags for blueshifted gas, and the two-dimensional velocity-delay map suggests a disk with some inflow. We compare our results with previous work and find evidence for different time lags despite similar luminosities, as well as evolving broad-line region structures. [ABSTRACT FROM AUTHOR]

We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk 142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatory for four months in X-rays and six different UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, the Liverpool Telescope, and the Dan Zowada Memorial Observatory in ugriz filters, as well as from the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength lightcurves. In the UV and optical, we find that the wavelength-dependent lags, τ(λ), generally follow the relation τ(λ) ∝ λ4/3, as expected for the T ∝ R−3/4 profile of a steady-state, optically thick, geometrically thin accretion disk, though they can also be fit by τ(λ) ∝ λ2, as expected for a slim disk. The exceptions are the u and U bands, where an excess lag is observed, as has been observed in other active galactic nuclei and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux–flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux dependence of the variable component is consistent with the fν ∝ ν1/3 spectrum expected for a geometrically thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate. [ABSTRACT FROM AUTHOR]

We investigate whether the correlation between the hard X-ray photon index () and accretion rate for super-Eddington accreting quasars is different from that for sub-Eddington accreting quasars. We construct a sample of 113 bright quasars from the Sloan Digital Sky Survey Data Release 14 quasar catalog, with 38 quasars as the super-Eddington subsample and 75 quasars as the sub-Eddington subsample. We derive black hole masses using a simple-epoch virial mass formula based on the lines, and we use the standard thin disk model to derive the dimensionless accretion rates () for our sample. The X-ray data for these quasars are collected from the Chandra and XMM-Newton archives. We fit the hard X-ray spectra using a single power-law model to obtain values. We find a statistically significant (,) correlation between and for the super-Eddington subsample. The – correlation for the sub-Eddington subsample is also significant, but weaker (,). Linear regression analysis shows that and for the super- and sub-Eddington subsamples, respectively. The – correlations of the two subsamples are different, suggesting different disk–corona connections in these two types of systems. We propose one qualitative explanation of the steeper – correlation in the super-Eddington regime that involves larger seed photon fluxes received by the compact coronae from the thick disks in super-Eddington accreting quasars. [ABSTRACT FROM AUTHOR]

We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns, including our ongoing campaign of monitoring super-Eddington accreting massive black holes (BHs). This sample covers a large range of BH mass , dimensionless accretion rates , and 5100 Å luminosity , allowing us to systematically study the AGN variability and their relations with BH mass, accretion rates, and optical luminosity. We employed the damped random walk (DRW) model to delineate the optical variability of continuum at 5100 Å and obtained damped variability timescale () and amplitude () using a Markov Chain Monte Carlo method. We also estimated the traditional variability amplitudes (), which provide a model-independent measure and therefore are used to test the DRW results. We found that AGN variability characteristics are generally correlated with. These correlations are smooth from sub-Eddington to super-Eddington accretion AGNs, probably implying that the AGN variability may be caused by the same physical mechanism. [ABSTRACT FROM AUTHOR]

This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting massive black holes (SEAMBHs) and to use their unique properties to construct a new method for measuring cosmological distances. Based on theoretical models, the saturated bolometric luminosity of such sources is proportional to the BH mass, which can be used to obtain their distance. Here we report on five new RM measurements and show that in four of the cases, we can measure the BH mass and three of these sources are SEAMBHs. Together with the three sources from our earlier work, we now have six new sources of this type. We use a novel method based on a minimal radiation efficiency to identify nine additional SEAMBHs from earlier RM-based mass measurements. We use a Bayesian analysis to determine the parameters of the new distance expression and the method uncertainties from the observed properties of the objects in the sample. The ratio of the newly measured distances to the standard cosmological ones has a mean scatter of 0.14 dex, indicating that SEAMBHs can be use as cosmological distance probes. With their high luminosity, long period of activity, and large numbers at high redshifts, SEAMBHs have a potential to extend the cosmic distance ladder beyond the range now explored by Type Ia supernovae. [ABSTRACT FROM AUTHOR]

For some samples, it has been shown that spectra of QSOs with low redshift are bluer during their brighter phases. For the FIRST bright QSO sample, we assemble their spectra from Sloan Digital Sky Survey Data Release 7 (SDSS DR7) to investigate variability between the spectra from White et al. and from the SDSS for a long rest-frame time lag, up to 10 years. There are 312 radio-loud (RL) QSOs and 232 radio-quiet (RQ) QSOs in this sample, up to z ∼ 3.5. With two-epoch variation, it is found that the spectra of half of the QSOs appear redder during their brighter phases. There is no obvious difference in slope variability between subsamples of RQ and RL QSOs. This result implies that the presence of a radio jet does not affect the slope variability on 10 year timescales. The arithmetic composite difference spectrum for variable QSOs is steep blueward of ∼2500 Å. The variability for the region blueward of 2500 Å is different to that for the region redward of 2500 Å. [ABSTRACT FROM AUTHOR]