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1. DAVOS: Dwarf Active Galactic Nuclei from Variability for the Origins of Seeds: Properties of Variability-selected Active Galactic Nuclei in the COSMOS Field and Expectations for the Rubin Observatory

   https://doi.org/10.3847/1538-4357/ad54ca  

   Burke, Colin J; Liu, Yichen; Ward, Charlotte A; Liu, Xin; Natarajan, Priyamvada; Greene, Jenny E (August 2024, The Astrophysical Journal)

   Abstract We study the black hole mass–host galaxy stellar mass relation,M_BH–M_*, of a sample ofz< 4 optically variable active galactic nuclei (AGNs) in the COSMOS field. The parent sample of 491 COSMOS AGNs were identified by optical variability from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) program. Using publicly available catalogs and spectra, we consolidate their spectroscopic redshifts and estimate virial black hole masses using broad-line widths and luminosities. We show that variability searches with deep, high-precision photometry like the HSC-SSP can identity AGNs in low-mass galaxies up toz∼ 1. However, their black holes are more massive given their host galaxy stellar masses than predicted by the local relation for active galaxies. We report thatz∼ 0.5–4 variability-selected AGNs are meanwhile more consistent with theM_BH–M_*relation for local inactive early-type galaxies. This result is in agreement with most previous studies of theM_BH–M_*relation at similar redshifts and indicates that AGNs selected from variability are not intrinsically different from the broad-line Type 1 AGN population at similar luminosities. Our results demonstrate the need for robust black hole and stellar mass estimates for intermediate-mass black hole candidates in low-mass galaxies at similar redshifts to anchor this scaling relation. Assuming that these results do not reflect a selection bias, they appear to be consistent with self-regulated feedback models wherein the central black hole and stars in galaxies grow in tandem. 

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2. Dwarf Active Galactic Nuclei from Variability for the Origins of Seeds (DAVOS): Properties of Variability-selected AGN in the Dark Energy Survey Deep Fields

   https://doi.org/10.3847/1538-4357/ae0e64  

   Liu, Yichen; Burke, Colin J; Miura, Diego; Liu, Xin; Yang, Qian; Natarajan, Priyamvada; Ward, Charlotte A (November 2025, The Astrophysical Journal)

   Abstract We study the black hole mass–host galaxy stellar mass relation,M_BH–M_*, for a sample of 706z ≲ 1.5 andi ≲ 24 optically variable active galactic nuclei (AGNs) in three Dark Energy Survey (DES) Deep Fields: C3, X3, E2, which partially cover Chandra Deep Field-South, XMM Large Scale Structure survey, and European Large Area ISO Survey, respectively. The parent sample was identified by optical variability from the DES supernova survey program imaging. Using publicly available spectra and photometric catalogs, we consolidate their spectroscopic redshifts, estimate their black hole masses using broad line widths and luminosities, and obtain improved stellar masses using spectral energy distribution fitting from X-ray to mid-infrared wavelengths. Our results confirm previous work from Hyper-Suprime Camera imaging that variability searches with deep, high-precision photometry can reliably identify AGNs in low-mass galaxies up toz ∼ 1. However, we find that the hosted black holes are more massive than predicted by the local AGN relation, fixing host galaxy stellar mass. Instead,z ∼ 0.1–1.5 variability-selected AGNs lie in between theM_BH–M_*relation for local inactive early-type galaxies and local active galaxies. This result agrees with most previous studies of theM_BH–M_*relation for AGNs at similar redshifts, regardless of the selection technique. We demonstrate that studies of variability-selected AGN provide critical insights into the low-mass end of theM_BH–M_*relation, shedding light on the occupation fraction of that provides constraints on early black hole seeding mechanisms and self-regulated feedback processes during their growth and coevolution with their hosts. 

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3. LLAMA: The M _BH – σ _⋆ relation of the most luminous local AGNs

   https://doi.org/10.1051/0004-6361/201936321  

   Caglar, Turgay; Burtscher, Leonard; Brandl, Bernhard; Brinchmann, Jarle; Davies, Richard I.; Hicks, Erin K.; Koss, Michael; Lin, Ming-Yi; Maciejewski, Witold; Müller-Sánchez, Francisco; et al (February 2020, Astronomy & Astrophysics)

   Context. The M BH – σ ⋆ relation is considered a result of coevolution between the host galaxies and their supermassive black holes. For elliptical bulge hosting inactive galaxies, this relation is well established, but there is still discussion concerning whether active galaxies follow the same relation. Aims. In this paper, we estimate black hole masses for a sample of 19 local luminous active galactic nuclei (AGNs; LLAMA) to test their location on the M BH – σ ⋆ relation. In addition, we test how robustly we can determine the stellar velocity dispersion in the presence of an AGN continuum and AGN emission lines, and as a function of signal-to-noise ratio. Methods. Supermassive black hole masses ( M BH ) were derived from the broad-line-based relations for H α , H β , and Pa β emission line profiles for Type 1 AGNs. We compared the bulge stellar velocity dispersion ( σ ⋆ ) as determined from the Ca II triplet (CaT) with the dispersion measured from the near-infrared CO (2-0) absorption features for each AGN and find them to be consistent with each other. We applied an extinction correction to the observed broad-line fluxes and we corrected the stellar velocity dispersion by an average rotation contribution as determined from spatially resolved stellar kinematic maps. Results. The H α -based black hole masses of our sample of AGNs were estimated in the range 6.34 ≤ log M BH  ≤ 7.75 M ⊙ and the σ ⋆CaT estimates range between 73 ≤  σ ⋆CaT  ≤ 227 km s −1 . From the so-constructed M BH  −  σ ⋆ relation for our Type 1 AGNs, we estimate the black hole masses for the Type 2 AGNs and the inactive galaxies in our sample. Conclusions. We find that our sample of local luminous AGNs is consistent with the M BH – σ ⋆ relation of lower luminosity AGNs and inactive galaxies, after correcting for dust extinction and the rotational contribution to the stellar velocity dispersion. 

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

   https://doi.org/10.3847/1538-4357/ae41ad  

   Bennert, Vardha N; Winkel, Nico; Treu, Tommaso; Ding, Xuheng; U, Vivian; Remigio, Raymond P; Barth, Aaron J; Malkan, Matthew A; Villafaña, Lizvette; Allen, Samantha; et al (March 2026, The Astrophysical Journal)

   Abstract Reverberation mapping (RM) determines the mass of black holes (BHs) in active galactic nuclei (AGNs) by resolving the BH gravitational sphere of influence in the time domain. Recent RM campaigns have 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 the spheroid, disk, and bar (if present). The spheroid effective radii are 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 accurateM_BH measurements of any AGN sample and provides a fundamental local benchmark for studies of the evolution of massive BHs and their host galaxies across cosmic time. 

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5. The Impact of Applying Black Hole–Host Galaxy Scaling Relations to Large Galaxy Populations

   https://doi.org/10.3847/1538-4357/ade30a  

   Huber, Maggie C; Simon, Joseph; Comerford, Julia M (July 2025, The Astrophysical Journal)

   Abstract Supermassive black holes (SMBHs) with dynamically measured masses have shown empirical correlations with host galaxy properties. These correlations are often the only method available to estimate SMBH masses and gather statistics for large galaxy populations across a range of redshifts, even though the scaling relations themselves are derived from a small subset of nearby galaxies. Depending on the scaling relation used, estimated SMBH masses can vary significantly. The most widely used scaling relations are theM_BH–M_bulgeandM_BH–σrelations, whereM_bulgeis galaxy bulge mass andσis the bulge velocity dispersion. In this paper, we determine how severely the choice of scaling relation impacts SMBH mass estimates for different subsets of a large galaxy population. For this analysis, we use a sample of ∼400,000 galaxies, including 1240 Type 1 active galactic nuclei from the Sloan Digital Sky Survey. We calculate SMBH masses fromM_BH–M_bulgeandM_BH–σand compare to single-epoch virial SMBH masses from broad-line Hβ, which are derived independently of black hole–host galaxy scaling relations. We find that SMBH masses derived from the single-epoch virial relation for Hβare better reproduced byM_BH–σthanM_BH–M_bulge. Finally, in cases whereσandM_bulgecannot be measured directly, we show that it is possible to inferσfrom photometry with more accuracy than we can inferM_bulge. 

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