Search for: All records

Abstract 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 〈f〉 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 betweenfand the shape of the broad Hβemission line, ${\log }_{10}(\mathrm{FWHM}/\sigma )$ . In this work, we update our sample to include 10 new sources withCARAMELBLR dynamical modeling, increasing both the black hole mass range and statistical power of our analysis. We find marginal evidence for a correlation betweenfand ${\log }_{10}(\mathrm{FWHM}/\sigma )$ , 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 impactsf. If confirmed with future BLR dynamical modeling of sources within a wider range of ${\log }_{10}(\mathrm{FWHM}/\sigma )$ , this relationship could enable empirical estimates of the virial coefficient and improve single-epoch black hole mass estimates across cosmic time. 

Abstract We describe photometric monitoring of the Seyfert 1 galaxy MCG–06-30-15 with the Las Cumbres Observatory network. Using theVfilter, 496 images were collected between 2023 December and 2024 June from observatories in Chile, South Africa, and Australia. We created light curves of the active galactic nucleus continuum emission using aperture photometry and image subtraction methods. We find that the typical magnitude difference between the two light curves is ΔV ≈ 1.9 mag, indicating that the host galaxy contributes approximately 85% of the total flux through the photometric aperture. The amplitude of variation is significantly enhanced when the host galaxy is removed: ΔV = 0.1 mag from aperture photometry compared to ΔV = 0.5 mag with image subtraction. Future work will compare the continuum light curve with the broad emission-line flux variations to provide insight into the physical parameters of the broad-line region in MCG–06-30-15 and the mass of the central supermassive black hole. 

Abstract Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). The source of this emission has long been thought to originate from the accretion disk, but recent studies suggest the broad-line region (BLR) may significantly contribute to both the observed flux and continuum interband delays. We monitored 18 AGN over 4 yr of observations to acquire high-quality optical continuum light curves, measuring time lags between different photometric bands and determining continuum emission sizes for each active galactic nucleus. We add this sample to existing lag measurements to test the correlation between continuum lags at 5100 Å (τ₅₁₀₀) and 5100 Å luminosity (L₅₁₀₀). We observe that ${\tau }_{5100}\propto L_{5100}^{0.4}$ , broadly consistent with the theoretical expectations ofτ ∝ L^1/2expected for continuum reverberation from either the accretion disk or the BLR. 

Abstract We presentV-band continuum light curves of the active galactic nucleus (AGN) in NGC 4151 created from a new photometric monitoring campaign with the Las Cumbres Observatory network. A total of 336 images were collected from 2023 December to 2024 June, with an average cadence of ∼2 images per day. Using aperture photometry and image subtraction, we constructed continuum light curves. Though both techniques generated similar light curves and demonstrated AGN variability on the scale of ΔV ≈ 0.4 mag, the galactic starlight contribution to the aperture photometry light curve produced a flux offset of ∼19% within a circular aperture of radius 31. The final light curves from this work will be compared against the variability of the broad emission lines to constrain the mass of the supermassive black hole and to model the broad-line region kinematics and geometry in NGC 4151. 

Abstract We present the stellar dynamical (SD) mass of the central black hole in the nearby Seyfert galaxy MCG–06-30-15 using the Schwarzschild orbit-superposition method implemented in the open-source codeFORSTAND. We obtained spatially resolvedK-band nuclear stellar spectra for this galaxy with SINFONI on the Very Large Telescope. We extracted the bulk stellar kinematics using Gauss–Hermite (GH) parameterization of the line-of-sight velocity distributions. A multicomponent surface-brightness profile of the galaxy was determined from a Hubble Space Telescope medium-bandVimage. Our best-fit models indicate a black hole mass ofM_BH = (4.4 ± 1.4) × 10⁷M_⊙and a stellar mass-to-light ratio ofM/L= (3.0 ± 0.3)M_⊙/L_⊙, within 1σconfidence intervals. Our constraint onM_BHagrees with an upper limit on the mass from stellar dynamics based on the Jeans anisotropic modeling method, but is ∼10 times larger than the reported mass from reverberation mapping (RM). However, our best-fitM_BHmay be systematically biased high due to the counterrotating disk in the nucleus of MCG–06-30-15 and the inability of the GH parameterization to fully describe such a complicated set of stellar kinematics. In addition, a dynamicalM_BHvalue depends heavily on the assumed source distance, which is not yet accurately constrained for this galaxy. MCG–06-30-15 is only the fourth galaxy in which we can compareM_BHfrom SD modeling with that from RM. A direct comparison ofM_BHallows us to identify and investigate the possible sources of bias associated with different mass measurement techniques, which may influence our understanding of black hole and galaxy coevolution across cosmological timescales. 

Abstract A recent study of the compact elliptical galaxy NGC 4486B using JWST Near-Infrared Spectrograph integral-field-unit-mode kinematics confirmed a supermassive black hole (SMBH) of mass ${\mathcal{M}}_{\mathrm{BH}}=3.6\pm 0.7\times 10^8$ (∼8% of the stellar mass). In addition to its double nucleus, the nuclear kinematics show pronounced asymmetries: a velocity dispersion peak displaced by 6 pc from the galaxy center and a ∼16 km s⁻¹offset in the mean stellar line-of-sight velocity near the SMBH. We examine the origin of the 12 pc double nucleus and show that the observations favor an SMBH surrounded by an eccentric nuclear disk (END). One proposed formation pathway for ENDs involves a gravitational-wave (GW) recoil of the SMBH following a binary merger. Our orbit superposition models contain ∼50% retrograde stars at the edge of the nuclear region, in agreement with END formation simulations. We infer a premerger mass ratioq > 0.15 and a recoil kick of ∼340 km s⁻¹. OurN-body simulations show that with such a kick, the SMBH returns to the center within ∼30 Myr. Its flat central core is also consistent with earlier “binary black hole scouring.” We test two alternative mechanisms—buoyancy-driven oscillations and a premerger SMBH binary—but neither reproduces the observed offsets, favoring the GW kick scenario. OurN-body simulations also show that a prograde SMBH binary in a rotating host can become trapped in a corotation resonance, delaying coalescence. Although NGC 4486B is an old galaxy near the Virgo Cluster center, its SMBH appears to have merged only recently, making its nucleus a rare nearby laboratory for postmerger SMBH dynamics. 

Abstract We describe the results of a new reverberation mapping program focused on the nearby Seyfert galaxy NGC 3227. Photometric and spectroscopic monitoring was carried out from 2022 December to 2023 June with the Las Cumbres Observatory network of telescopes. We detected time delays in several optical broad emission lines, with Hβhaving the longest delay at ${\tau }_{\mathrm{cent}}={4.0}_{-0.9}^{+0.9}$ days and Heiihaving the shortest delay with ${\tau }_{\mathrm{cent}}={0.9}_{-0.8}^{+1.1}$ days. We also detect velocity-resolved behavior of the Hβemission line, with different line-of-sight velocities corresponding to different observed time delays. Combining the integrated Hβtime delay with the width of the variable component of the emission line and a standard scale factor suggests a black hole mass of $M_{\mathrm{BH}}={1.1}_{-0.3}^{+0.2}\times {10}^7$ M_⊙. Modeling of the full velocity-resolved response of the Hβemission line with the phenomenological codeCARAMELfinds a similar mass of $M_{\mathrm{BH}}={1.2}_{-0.7}^{+1.5}\times {10}^7$ M_⊙and suggests that the Hβ-emitting broad-line region (BLR) may be represented by a biconical or flared disk structure that we are viewing at an inclination angle ofθ_i≈ 33° and with gas motions that are dominated by rotation. The new photoionization-based BLR modeling toolBELMACfinds general agreement with the observations when assuming the best-fitCARAMELresults; however,BELMACprefers a thick-disk geometry and kinematics that are equally composed of rotation and inflow. Both codes infer a radially extended and flattened BLR that is not outflowing. 

Abstract We present an analysis of Hubble Space Telescope COS/G160M observations of CIVin the inner circumgalactic medium (CGM) of a novel sample of eightz∼ 0,L≈L^⋆galaxies, paired with UV-bright QSOs at impact parameters (R_proj) between 25 and 130 kpc. The galaxies in this stellar-mass-controlled sample (log₁₀M_⋆/M_⊙∼ 10.2–10.9M_⊙) host supermassive black holes (SMBHs) with dynamically measured masses spanning log₁₀M_BH/M_⊙∼ 6.8–8.4; this allows us to compare our results with models of galaxy formation where the integrated feedback history from the SMBH alters the CGM over long timescales. We find that the CIVcolumn density measurements (N_{C IV}; average log₁₀N_{C IV,CH}= 13.94 ± 0.09 cm⁻²) are largely consistent with existing measurements from other surveys ofN_{C IV}in the CGM (average log₁₀N_{C IV,Lit}= 13.90 ± 0.08 cm⁻²), but do not show obvious variation as a function of the SMBH mass. By contrast, specific star formation rate (sSFR) is highly correlated with the ionized content of the CGM. We find a large spread in sSFR for galaxies with log₁₀M_BH/M_⊙> 7.0, where the CGM CIVcontent shows a clear dependence on galaxy sSFR but notM_BH. Our results do not indicate an obvious causal link between CGM CIVand the mass of the galaxy’s SMBH; however, through comparisons to the EAGLE, Romulus25, and IllustrisTNG simulations, we find that our sample is likely too small to constrain such causality. 

Abstract The integral-field unit mode of the Near-Infrared Spectrograph (NIRSpec+IFU) mounted on the James Webb Space Telescope has now enabled kinematic studies of smaller and less massive compact stellar systems in which to search for central massive black holes (BHs) than ever before. We present here the first such detection using NIRSpec+IFU in its highest resolution (R ∼ 2700) mode. We report the detection of a central BH with mass ${\mathcal{M}}_{\mathrm{BH}}$ = 2.1 ± 1.1 × 10⁶M_⊙(1σuncertainties) in UCD736 orbiting within the Virgo galaxy cluster. Schwarzschild modeling of the 1D kinematic profile rules out a zero-mass central BH at the 3σlevel; however, two other independent modeling approaches fail to rule out a zero-mass BH at >1σsignificance. The presence of such a massive BH strongly argues against a globular cluster origin of this ultracompact dwarf galaxy (UCD), and rather suggests a tidally stripped formation route from a former ≳10⁹M_⊙dwarf galaxy host. This represents the detection of a BH in the most compact (r_h ≈ 15 pc) stellar system to date, with a ${\mathcal{M}}_{\mathrm{BH}}$ corresponding to ∼8% of the system’s stellar mass, roughly in line with previously reported UCD BH detections and comparable to the BH detected in the compact elliptical galaxy NGC4486B. 

Abstract We present a new constraint on the mass of the black hole in the active S0 galaxy NGC 5273. Due to the proximity of the galaxy at 16.6 ± 2.1 Mpc, we were able to resolve and extract the bulk motions of stars near the central black hole using adaptive-optics-assisted observations with the Gemini Near-infrared Integral Field Spectrograph, as well as constrain the large-scale kinematics using archival Spectroscopic Areal Unit for Research and Optical Nebulae spectroscopy. High-resolution Hubble Space Telescope imaging allowed us to generate a surface-brightness decomposition, determine approximate mass-to-light ratios for the bulge and disk, and obtain an estimate for the disk inclination. We constructed an extensive library of dynamical models using the Schwarzschild orbit-superposition code FORSTAND, exploring a range of disk and bulge shapes, halo masses, etc. We determined a black hole mass of M • = [0.5–2] × 10 7 M ⊙ , where the low side of the range is in agreement with the reverberation mapping measurement of M • = [4.7 ± 1.6] × 10 6 M ⊙ . NGC 5273 is one of the few nearby galaxies that hosts a broad-lined active galactic nucleus, allowing a crucial comparison of black hole masses derived from independent mass-measurement techniques.