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1. The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results

   https://doi.org/10.3847/1538-4365/ad3936  

   Shen, Yue; Grier, Catherine_J; Horne, Keith; Stone, Zachary; Li, Jennifer_I; Yang, Qian; Homayouni, Yasaman; Trump, Jonathan_R; Anderson, Scott_F; Brandt, W_N; et al (May 2024, The Astrophysical Journal Supplement Series)

   Abstract We present the final data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to the SDSS-V Black Hole Mapper RM program. This data set includes 11 yr photometric and 7 yr spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1 <z< 4.5 and a luminosity range ofL_bol= 10^44−47.5erg s⁻¹, along with spectral and variability measurements. We report 23, 81, 125, and 110 RM lags (relative to optical continuum variability) for broad Hα, Hβ, Mgii, and Civusing the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM active galactic nuclei with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of $\left(\log f\right)=0.62\pm 0.07$for the line dispersion measured from the rms spectrum. The intrinsic scatter of individual virial factors is 0.31 ± 0.07 dex, indicating a factor of 2 systematic uncertainty in RM black hole masses. Our lag measurements reveal significantR–Lrelations for Hβand Mgiiat high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of theR–Lrelation for Civgiven the limited dynamic range in luminosity, we found substantially larger scatter in Civlags at fixedL₁₃₅₀. Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for Hβ, Mgii, and Civ, which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new Hβand Mgiirecipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the Civrecipe. The intrinsic scatter of SE masses around RM masses is ∼0.45 dex for Hβand Mgii, increasing to ∼0.58 dex for Civ. 

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2. AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope*

   https://doi.org/10.3847/1538-4357/acc45a  

   Homayouni, Y.; De Rosa, Gisella; Plesha, Rachel; Kriss, Gerard A.; Barth, Aaron J.; Cackett, Edward M.; Horne, Keith; Kara, Erin A.; Landt, Hermine; Arav, Nahum; et al (May 2023, The Astrophysical Journal)

   Abstract We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk 817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultraviolet observations are accompanied by X-ray, optical, and near-infrared observations as part of the AGN Space Telescope and Optical Reverberation Mapping Program 2 (AGN STORM 2). Using the cross-correlation lag analysis method, we find significant correlated variations in the continuum and emission-line light curves. We measure rest-frame delayed responses between the far-ultraviolet continuum at 1180 Å and Ly α λ 1215 Å ( 10.4 − 1.4 + 1.6 days), N v λ 1240 Å ( 15.5 − 4.8 + 1.0 days), Si iv + ]O iv λ 1397 Å ( 8.2 − 1.4 + 1.4 days), C iv λ 1549 Å ( 11.8 − 2.8 + 3.0 days), and He ii λ 1640 Å ( 9.0 − 1.9 + 4.5 days) using segments of the emission-line profile that are unaffected by absorption and blending, which results in sampling different velocity ranges for each line. However, we find that the emission-line responses to continuum variations are more complex than a simple smoothed, shifted, and scaled version of the continuum light curve. We also measure velocity-resolved lags for the Ly α and C iv emission lines. The lag profile in the blue wing of Ly α is consistent with virial motion, with longer lags dominating at lower velocities, and shorter lags at higher velocities. The C iv lag profile shows the signature of a thick rotating disk, with the shortest lags in the wings, local peaks at ±1500 km s −1 , and a local minimum at the line center. The other emission lines are dominated by broad absorption lines and blending with adjacent emission lines. These require detailed models, and will be presented in future work. 

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3. Robotic reverberation mapping of the broad-line radio galaxy 3C 120

   https://doi.org/10.1093/mnras/staa2171  

   Hlabathe, Michael S; Starkey, David A; Horne, Keith; Romero-Colmenero, Encarni; Crawford, Steven M; Valenti, Stefano; Winkler, Hartmut; Barth, Aaron J; Onken, Christopher A; Sand, David J; et al (September 2020, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We carried out photometric and spectroscopic observations of the well-studied broad-line radio galaxy 3C 120 with the Las Cumbres Observatory (LCO) global robotic telescope network from 2016 December to 2018 April as part of the LCO AGN Key Project on Reverberation Mapping of Accretion Flows. Here, we present both spectroscopic and photometric reverberation mapping results. We used the interpolated cross-correlation function to perform multiple-line lag measurements in 3C 120. We find the H γ, He ii λ4686, H β, and He i λ5876 lags of $$\tau _{\text{cen}} = 18.8_{-1.0}^{+1.3}$$, $$2.7_{-0.8}^{+0.7}$$, $$21.2_{-1.0}^{+1.6}$$, and $$16.9_{-1.1}^{+0.9}$$ d, respectively, relative to the V-band continuum. Using the measured lag and rms velocity width of the H β emission line, we determine the mass of the black hole for 3C 120 to be $$M=(6.3^{+0.5}_{-0.3})\times 10^7\, (f/5.5)$$ M⊙. Our black hole mass measurement is consistent with similar previous studies on 3C 120, but with small uncertainties. In addition, velocity-resolved lags in 3C 120 show a symmetric pattern across the H β line, 25 d at line centre decreasing to 17 d in the line wings at ±4000 km s−1. We also investigate the inter-band continuum lags in 3C 120 and find that they are generally consistent with τ ∝ λ4/3 as predicted from a geometrically thin, optically thick accretion disc. From the continuum lags, we measure the best-fitting value τ0 = 3.5 ± 0.2 d at $$\lambda _{\rm 0} = 5477\, \mathring{\rm A}$$. It implies a disc size a factor of 1.6 times larger than prediction from the standard disc model with L/LEdd = 0.4. This is consistent with previous studies in which larger than expected disc sizes were measured. 

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4. Monitoring AGNs with Hβ Asymmetry. III. Long-term Reverberation Mapping Results of 15 Palomar–Green Quasars

   https://doi.org/10.3847/1538-4365/ac7beb  

   Bao, Dong-Wei; Brotherton, Michael S.; Du, Pu; McLane, Jacob N.; Zastrocky, T. E.; Olson, Kianna A.; Fang, Feng-Na; Zhai, Shuo; Huang, Zheng-Peng; Wang, Kai; et al (August 2022, The Astrophysical Journal Supplement Series)

   Abstract In this third paper of the series reporting on the reverberation mapping campaign of active galactic nuclei with asymmetric H β emission-line profiles, we present results for 15 Palomar–Green quasars using spectra obtained between the end of 2016–2021 May. This campaign combines long time spans with relatively high cadence. For eight objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of nine of our targets has been attempted for the first time, while the results for six others can be compared with previous campaigns. We measure the H β time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad-line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than that of outflow. 

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5. Toward measuring supermassive black hole masses with interferometric observations of the dust continuum

   https://doi.org/10.1051/0004-6361/202244655  

   Amorim, A.; Bourdarot, G.; Brandner, W.; Cao, Y.; Clénet, Y.; Davies, R.; de Zeeuw, P. T.; Dexter, J.; Drescher, A.; Eckart, A.; et al (January 2023, Astronomy & Astrophysics)

   This work focuses on active galactic nuclei (AGNs) and on the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H β BLR size, with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence simply be derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and they are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate a measuring of the BH mass based on the dust-continuum size with our first calibration of the R BLR – R d relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential of measuring BH masses for a large sample of AGNs in the low-redshift Universe. 

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