We present a study of the cold molecular gas kinematics in the inner ∼4–7 kpc (projected sizes) of three nearby Seyfert galaxies with active galactic nucleus (AGN) luminosities of ∼1044 erg s−1 using observations of the CO(2–1) emission line obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at ∼0.5–0.8″ (∼150–400 pc) spatial resolutions. After modeling the CO profiles with multiple Gaussian components, we detected regions with double-peak profiles that exhibit kinematics distinct from the dominant rotational motion. In NGC 6860, a molecular outflow surrounding the bipolar emission of the [O III] ionized gas is observed extending up to Rout ∼ 560 pc from the nucleus. There is evidence of molecular inflows along the stellar bar, although an alternative scenario involving a decoupled rotation in a circumnuclear disk (CND) can also explain the observed kinematics. Mrk 915 shows double-peak CO profiles along one of its spiral arms. Due to the ambiguous orientation of its disk, part of the CO emission can be interpreted as a molecular gas inflow or an outflow reaching Rout ∼ 2.8 kpc. MCG -01-24-012 has double-peak profiles associated with a CND perpendicular to the [O III] bipolar emission. The CO in the CND is rotating while outflowing within Rout ∼ 3 kpc, with the disturbances possibly being caused by the passage of the ionized gas outflow. Overall, the mass inflow rates are larger than the accretion rate needed to produce the observed luminosities, suggesting that only a fraction of the inflowing gas ends up feeding the central black holes. Although we found signatures of AGN feedback on the cold molecular phase, the mass outflow rates of ∼0.09–3 M⊙ yr−1 indicate an overall weak impact at these AGN luminosities. Nonetheless, we may be witnessing the start of the depletion and ejection of the molecular gas reservoir that has accumulated over time.

We present results of a blind search for line-emitting galaxies using Atacama Large Millimeter/submillimeter Array (ALMA) Lensing Cluster Survey data. We detected seven line emitters, one of which is [C ii ] at z = 6.071, four are CO at z = 0.8–1.1, and the remaining two are possibly CO or [C i ] within photometric redshift ranges. Three of the four CO emitters are multiple images of the same galaxy. Compared to previous line-emitter searches in ALMA deep fields, our sample probes molecular gas masses ∼1 dex below the lower bound, thanks to gravitational lensing (typically μ ∼ 4, up to ∼30 in extreme cases). Most emitters are located in a region similar to normal star-forming galaxies in the star formation rate (SFR) versus molecular gas mass plane. To reduce dependence on SFR and stellar mass, we analyzed the molecular gas fraction and depletion timescale as a function of distance from the star formation main sequence. We found that most emitters broadly follow the scaling relations from previous studies, consistent within the intrinsic scatter. In addition, we serendipitously detected the CH N = 1, J = 3/2 → 1/2 Λ-doublet transition from one CO emitter at z = 1.142, representing the first detection of CH from an individual galaxy at cosmological distances through a blind survey. The CH/CO column density ratio of ∼10 ^−4 is comparable to that of local active galactic nucleus (AGN)-host galaxies, suggesting that CH traces molecular gas associated with AGN activity, possibly irradiated by X-rays.

NGC 6411, an isolated elliptical galaxy, appears in the literature with an intermediate age of 3.5 Gyr. Its globular cluster system (GCS), on the other hand, has all the properties of a very old age. The knowledge of the stellar M/L ratio is necessary to evaluate its mass discrepancy. NGC 6411 has a low central surface brightness, which makes it a valuable test object for Modified Newtonian Dynamics (MOND). We reconsider the conflict between age and GCS properties. We perform a stellar population analysis to constrain its baryonic mass and do a kinematical analysis to constrain the total mass. We use data cubes from the CALIFA (Calar Alto Legacy Integral Field Area) survey to investigate the stellar population and measure velocity dispersions of NGC 6411, employing the spectral synthesis codes Starlight and ppxf. The dynamical analysis is based on spherical Jeans models. Using Starlight, an intermediate age of NGC 6411 results only as a Single Stellar Population (SSP) age with a fixed reddening. This seems to be caused by a slightly erroneous continuum slope. ppxf, which does not fit the continuum, gives an SSP age of 12 Gyr. A simple isotropic MOND model reproduces the projected velocity dispersions well. NGC 6411 joins the list of early-type galaxies for which MOND makes a successful prediction. It is special in the sense that due to its low surface brightness, MOND effects become visible at smaller radii than in other elliptical galaxies.

Context. The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed, including the main science targets, Sgr A* and M 87, and various calibrators. Sixteen sources were AGN. Aims. We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-Konigl (BK) jet model. In particular, we aimed to study the signatures of jet acceleration and magnetic energy conversion. Methods. We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components (1749+096, 1055+018, BL Lac, J0132-1654, J0006-0623, CTA 102, and 3C 454.3) and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2-86 GHz range. Combining these data into a multifrequency EHT+ data set, we studied the dependences of the VLBI core component flux density, size, and brightness temperature on the frequency measured in the AGN host frame (and hence on the distance from the central black hole), characterizing them with power law fits. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole. Results. Our observations spanning event horizon to parsec scales indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Only some of the discrepancies may be alleviated by tweaking the model parameters or the jet collimation profile. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations. For our sample, we estimate a general radial dependence of the Doppler factor delta proportional to r(<= 0.5). This interpretation is consistent with a magnetically accelerated sub-parsec jet. We also estimate a steep decrease of the magnetic field strength with radius B proportional to r(-3), hinting at jet acceleration or efficient magnetic energy dissipation.

The Event Horizon Telescope (EHT) has produced resolved images of the supermassive black holes (SMBHs) Sgr A* and M87*, which present the largest shadows on the sky. In the next decade, technological improvements and extensions to the array will enable access to a greater number of sources, unlocking studies of a larger population of SMBHs through direct imaging. In this paper, we identify 12 of the most promising sources beyond Sgr A* and M87* based on their angular size and millimeter flux density. For each of these sources, we make theoretical predictions for their observable properties by ray tracing general relativistic magnetohydrodynamic models appropriately scaled to each target’s mass, distance, and flux density. We predict that these sources would have somewhat higher Eddington ratios than M87*, which may result in larger optical and Faraday depths than previous EHT targets. Despite this, we find that visibility amplitude size constraints can plausibly recover masses within a factor of 2, although the unknown jet contribution remains a significant uncertainty. We find that the linearly polarized structure evolves substantially with the Eddington ratio, with greater evolution at larger inclinations, complicating potential spin inferences for inclined sources. We discuss the importance of 345 GHz observations, milli-Jansky baseline sensitivity, and independent inclination constraints for future observations with upgrades to the EHT through ground updates with the next-generation EHT program and extensions to space through the black hole Explorer.

We present high-resolution (∼50–100 pc) Atacama Large Millimeter/submillimeter Array observations of ^12 CO(2–1) or ^12 CO(1–0) emission in seven local ( z ≲ 0.05) major mergers—five of which are dual active galactic nucleus (AGN) systems, and two of which are single AGN systems. We model the molecular gas kinematics through rotating disk profiles using a Bayesian Markov Chain Monte Carlo approach. The residuals were then used to isolate nonrotating components of the molecular gas—the most likely contributor to future supermassive black hole (SMBH) growth. We find that more-massive SMBHs have higher surface densities of nonrotating molecular gas within their sphere of influence. This potential molecular gas supply, however, does not correlate with the current accretion efficiency of the SMBHs, suggesting that only a fraction of the observed nonrotating gas is currently reaching the SMBH. Finally, we tentatively find no significant differences in the nuclear molecular gas masses of single-AGN and dual-AGN hosts, both within the SMBH sphere of influence and within the central kiloparsec. Our results indicate that the probability of occurrence of the dual AGN phenomenon is likely dependent on AGN variability and/or obscuration rather than the availability of molecular gas in the nuclear regions.

We investigate the origin of the elliptical ring structure observed in the images of the supermassive black hole M87*, aiming to disentangle contributions from gravitational, astrophysical, and imaging effects. Leveraging the enhanced capabilities of the Event Horizon Telescope (EHT)'s 2018 array, including improved (u,v)-coverage from the Greenland Telescope, we measured the ring's ellipticity using five independent imaging methods, obtaining a consistent average value of tau = 0.08(-0.02)(+0.03) with a position angle of xi = 50.1(-7.6)(+6.2) degrees. To interpret this measurement, we compared it to general relativistic magnetohydrodynamic (GRMHD) simulations spanning a wide range of physical parameters including the thermal or nonthermal electron distribution function, spins, and ion-to-electron temperature ratios in both low- and high-density regions. We find no statistically significant correlation between spin and ellipticity in GRMHD images. Instead, we identify a correlation between ellipticity and the fraction of non-ring emission, particularly in nonthermal models and models with higher jet emission. These results indicate that the ellipticity measured from the M87* emission structure is consistent with that expected from simulations of turbulent accretion flows around black holes, where it is dominated by astrophysical effects rather than gravitational ones. Future high-resolution imaging, including space very long baseline interferometry and long-term monitoring, will be essential to isolate gravitational signatures from astrophysical effects.

We present results of a blind search for line-emitting galaxies using ALMA Lensing Cluster Survey data. We detected seven line emitters, one of which is [C ii] at z = 6.071, four are CO at z = 0.8–1.1, and the remaining two are possibly CO or [C i] within photometric redshift ranges. Three of the four CO emitters are multiple images of the same galaxy. Compared to previous line-emitter searches in ALMA deep fields, our sample probes molecular gas masses ∼1 dex below the lower bound, thanks to gravitational lensing (typically μ∼ 4, up to ∼30 in extreme cases). Most emitters are located in a region similar to normal star-forming galaxies in the star formation rate (SFR) versus molecular gas mass plane. To reduce dependence on SFR and stellar mass, we analyzed the molecular gas fraction and depletion timescale as a function of distance from the star-formation main sequence. We found that most emitters broadly follow the scaling relations from previous studies, consistent within the intrinsic scatter. In addition, we serendipitously detected the CH N = 1, J = 3/2 → 1/2 Λ-doublet transition from one CO emitter at z = 1.142, representing the first detection of CH from an individual galaxy at cosmological distances through a blind survey. The CH/CO column density ratio of ∼10^-4 is comparable to that of local AGN-host galaxies, suggesting that CH traces molecular gas associated with AGN activity, possibly irradiated by X-rays.

Context. Active galactic nuclei (AGNs) exhibit a wide range of black hole masses and inflow/outflow properties. It is now possible to probe regions close to the event horizons of nearby supermassive black holes (SMBHs) using very long baseline interferometry (VLBI) with earth-sized baselines, as performed by the Event Horizon Telescope (EHT). Aims. This study explores the emission properties of accretion and outflows near the event horizon of both low-mass and high-mass SMBHs. Using resistive general relativistic magnetohydrodynamic (GR-MHD) simulations, we model AGNs with thin Keplerian disks. This contrasts with widely studied models featuring thick disks, such as magnetically arrested disks (MADs) or the standard and normal evolution (SANE) scenario. Methods. Our GR-MHD models serve as simplified representations to study disk-jet-wind structures. These simulations are postprocessed and ray-traced, using constraints of black hole mass and observed spectral energy distributions (SEDs). Thermal synchrotron emission generated near the event horizon is used to create emission maps, which are analysed by separating accretion and outflow components to determine their contributions to the total intensity. Results. Whether the emission appears optically thick or thin at a given frequency depends on its position relative to the synchrotron SED peak. At 230 GHz, low-mass SMBHs appear optically thicker than high-mass ones, even at lower accretion rates. Doppler beaming affects the brightness of emission from outflows with changing viewing angles in low-mass systems. Conclusions. Eddington ratios from our models align with those inferred by the EHTC for M87 and SgrA* using thicker MAD/SANE models. Although thin disks are optically thicker, their spectral properties make high-mass systems appear optically thinner at 230 GHz-ideal for probing GR effects like photon rings. In contrast, low-mass systems remain optically thicker at these frequencies because of synchrotron self-absorption, making outflow emissions near the horizon more pronounced. However, distinguishing these features remains challenging with current EHT resolution.

We present a study of the cold molecular versus ionized gas distribution in three nearby Seyfert galaxies: NGC 6860, Mrk 915, and MCG -01-24-012. To constrain the cold molecular flux distribution at similar to 0.5-0.8 '' (similar to 150-400 pc) scales, we used data from the CO(2-1) emission line, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). For the ionized gas, we used Hubble Space Telescope (HST) narrowband images, centered on the [O III]lambda lambda 4959,5007 emission lines. Within the inner kiloparsec of the three galaxies, we observe gaps in the CO emission in regions co-spatial with the [O III] flux distribution, similarly to what has recently been observed in other active galaxies. Of our original sample of 13 nearby active galactic nucleus (AGN) sources, 12 objects present the same trend. This indicates that CO molecules might be partially dissociated by AGN radiation or that there is a deficit of cold molecular gas on nuclear scales driven by ionized gas outflows and/or jets. If so, this represents a form of AGN feedback that is not captured when only outflow kinematic properties, such as mass outflow rates, are considered. We also discuss how part of the molecular gas might still be present in hotter H-2 phases, as has already been observed in other objects.

We present a study of the cold molecular gas kinematics in the inner ~ 4-7 kpc (projected sizes) of three nearby Seyfert galaxies, with AGN luminosities of ~ 10$^{44}$ erg/s, using observations of the CO(2-1) emission line, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at ~ 0.5-0.8$^{\prime\prime}$ (~ 150-400 pc) spatial resolutions. After modeling the CO profiles with multiple Gaussian components, we detected regions with double-peak profiles that exhibit kinematics distinct from the dominant rotational motion. In NGC 6860, a molecular outflow surrounding the bipolar emission of the [O III] ionized gas is observed extending up to $R_{out}$ ~ 560 pc from the nucleus. There is evidence of molecular inflows along the stellar bar, although an alternative scenario, involving a decoupled rotation in a circumnuclear disk (CND) can also explain the observed kinematics. Mrk 915 shows double-peak CO profiles along one of its spiral arms. Due to its ambiguous disk orientation, part of the CO emission can be interpreted as a molecular gas inflow or an outflow reaching $R_{out}$ ~ 2.8 kpc. MCG -01-24-012 has double-peak profiles associated with a CND, perpendicular to the [O III] bipolar emission. The CO in the CND is rotating while outflowing within $R_{out}$ ~ 3 kpc, with the disturbances possibly being caused by the passage of the ionized gas outflow. Overall, the mass inflow rates are larger than the accretion rate needed to produce the observed luminosities, suggesting that only a fraction of the inflowing gas ends up feeding the central black holes. Although we found signatures of AGN feedback on the cold molecular phase, the mass outflow rates of ~ 0.09-3 M$_\odot$/yr indicate an overall weak impact at these AGN luminosities. Nonetheless, we may be witnessing the start of the depletion and ejection of the molecular gas reservoir that has accumulated over time.

Aims. We aim to measure the mass of the supermassive black hole (SMBH) in the S0 galaxy NGC 4751 using CO J:3-2 emission from the 5 ''-scale nuclear rotating molecular disk. Methods. We imaged the kpc-scale molecular gas disk in NGC 4751 at 0.'' 22 (similar to 28 pc) spatial and 28 km s-1 spectral resolution in the CO J:3-2 emission line and neighboring continuum, with the Atacama Large Millimeter Array (ALMA). We used Hubble Space Telescope (HST) imaging and stellar and ionized gas kinematics at 100 pc to kpc-scales, derived from integral field spectroscopy, to determine the galaxy morphology and the circular velocity attributed to the stellar potential. We used the Markov chain Monte Carlo (MCMC) algorithm in the KINematic Molecular Simulation (KinMS) package to obtain the model parameters that best fit the observed molecular gas kinematics in the ALMA datacube. Results. Strong CO emission was detected over radii of similar to 0.'' 2 to 5 '', with isolated CO clumps detected out to 7 ''. The molecular disk kinematics is axisymmetric and rotation-dominated, with radial velocities between 400 km s(-1) and 660 km s(-1), a kinematic major axis position angle (PA) of 355 degrees, and an inclination close to 78 degrees. The intrinsic velocity dispersion is similar to 16 km s(-1), and there is no evidence for significant non-rotational kinematics. The kinematic center of the disk coincides with the compact nuclear 345 GHz source. The SMBH sphere of influence (SOI) is well resolved along all position angles. The (rotation) velocity curve due to the stellar potential ( Vradialmax similar to 430 V radial max similar to 430 V (max)(radia) km s-1) is determined by fitting the luminosity profile of NGC 4751 in an (H-band) image from the Wide Field Camera 3 (WFC3) aboard HST, and constraining the mass-to-light ratio (M/L) at this waveband using the molecular- and ionized-gas kinematics at radii greater than or similar to 4 '', outside the SMBH SOI. Several KinMS fits, all using a distance (D) of 26.3 Mpc, but with variations in other input quantities, resulted in SMBH masses of 3.22 - 4.33 x 10(9) M-circle dot and M/L values of 1.1-2.3 in the F160W band. In each fit, the statistical errors of these values are on the level of a few percent. Conclusions. Based on the results of the multiple KinMS fits, we argued for and adopted a value of 3.3 x 109 (D/26.3) M circle dot for the black hole mass, along with a (constant with radius) M/L of 2.28/(26.3/D)2 in the F160W band. We estimated the (one sigma) errors to be 20% in each of these. We find that the primary driver of the uncertainty (apart from distance) is the stellar potential in this dusty S0 galaxy. This CO-based mass is similar to 2.4 times higher than a previous stellar-dynamics based SMBH mass measurement using the same distance. We argue that this new value is more robust given the clear and well resolved Keplerian-rotation dominated signature in the molecular disk, as well as its robust values of inclination (78 degrees) and PA (355 degrees), further supported by the consistency among derived values across different datasets and methods.

AGNs exhibit a wide range of black hole masses and inflow/outflow properties. It is now possible to probe regions close to the event horizons of nearby SMBHs using VLBI with earth-sized baselines, as performed by the EHT. This study explores the emission properties of accretion and outflows near the event horizon of both low-mass and high-mass SMBHs. Using resistive GR-MHD simulations, we model AGNs with thin Keplerian disks. This contrasts with widely studied models featuring thick disks, such as magnetically arrested disks (MADs) or the standard and normal evolution (SANE) scenario. Our models serve as simplified representations to study disk-jet-wind structures. These simulations are postprocessed and ray-traced, using constraints of black hole mass and observed SEDs. Thermal synchrotron emission generated near the event horizon is used to create emission maps, which are analysed by separating accretion and outflow components to determine their contributions to the total intensity. Whether the emission appears optically thick or thin at a given frequency depends on its position relative to the synchrotron SED peak. At 230 GHz, low-mass SMBHs appear optically thicker than high-mass ones, even at lower accretion rates. Doppler beaming affects the brightness of emission from outflows with changing viewing angles in low-mass systems. Eddington ratios from our models align with those inferred by the EHTC for M87 and SgrA* using thicker MAD/SANE models. Although thin disks are optically thicker, their spectral properties make high-mass systems appear optically thinner at 230 GHz; ideal for probing GR effects like photon rings. In contrast, low-mass systems remain optically thicker at these frequencies because of synchrotron self-absorption, making outflow emissions near the horizon more pronounced. However, distinguishing these features remains challenging with current EHT resolution.

The Event Horizon Telescope (EHT) observation of M87∗ in 2018 has revealed a ring with a diameter that is consistent with the 2017 observation. The brightest part of the ring is shifted to the southwest from the southeast. In this paper, we provide theoretical interpretations for the multi-epoch EHT observations for M87∗ by comparing a new general relativistic magnetohydrodynamics model image library with the EHT observations for M87∗ in both 2017 and 2018. The model images include aligned and tilted accretion with parameterized thermal and nonthermal synchrotron emission properties. The 2018 observation again shows that the spin vector of the M87∗ supermassive black hole is pointed away from Earth. A shift of the brightest part of the ring during the multi-epoch observations can naturally be explained by the turbulent nature of black hole accretion, which is supported by the fact that the more turbulent retrograde models can explain the multi-epoch observations better than the prograde models. The EHT data are inconsistent with the tilted models in our model image library. Assuming that the black hole spin axis and its large-scale jet direction are roughly aligned, we expect the brightest part of the ring to be most commonly observed 90 deg clockwise from the forward jet. This prediction can be statistically tested through future observations.

In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M87. These images reveal a ring with a southerly brightness distribution and a diameter of similar to 42 mu as, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear EHT observations provide independent snapshots of the horizon-scale emission, allowing us to confirm the persistence, size, and shape of the black hole shadow, and constrain the intrinsic structural variability of the accretion flow. We have confirmed the presence of an asymmetric ring structure, brighter in the southwest, with a median diameter of 43 :3(-3:1)(+1:5) mu as. The diameter of the 2018 ring is remarkably consistent with the diameter obtained from the previous 2017 observations. On the other hand, the position angle of the brightness asymmetry in 2018 is shifted by about 30 degrees relative to 2017. The perennial persistence of the ring and its diameter robustly support the interpretation that the ring is formed by lensed emission surrounding a Kerr black hole with a mass similar to 6 :5 Chi 10(9) M-circle dot. The significant change in the ring brightness asymmetry implies a spin axis that is more consistent with the position angle of the large-scale jet.

Context. 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz. Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84. Methods. We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. Results. We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017–2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84. Conclusions. The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However, systematic uncertainties due to the limited (u, v)-coverage, however, cannot be ignored. Our upcoming work using new EHT data, which offer full imaging capabilities, will shed more light on the compact region of 3C 84.

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow.

ABSTRACT Supermassive Black Holes (SMBHs) are commonly found at the centres of massive galaxies. Estimating their masses (MBH) is crucial for understanding galaxy-SMBH co-evolution. We present WISE2MBH, an efficient algorithm that uses cataloged Wide-field Infrared Survey Explorer (WISE) magnitudes to estimate total stellar mass (M*) and scale this to bulge mass (MBulge), and MBH, estimating the morphological type (TType) and bulge fraction (B/T) in the process. WISE2MBH uses scaling relations from the literature or developed in this work, providing a streamlined approach to derive these parameters. It also distinguishes QSOs from galaxies and estimates the galaxy TType using WISE colours with a relation trained with galaxies from the 2MASS Redshift Survey. WISE2MBH performs well up to z ∼ 0.5 thanks to K-corrections in magnitudes and colours. WISE2MBH MBH estimates agree very well with those of a selected sample of local galaxies with MBH measurements or reliable estimates: a Spearman score of ∼0.8 and a RMSE of ∼0.63 were obtained. When applied to the ETHER sample at z ≤ 0.5, WISE2MBH provides ∼1.9 million MBH estimates (78.5 per cent new) and ∼100 thousand upper limits. The derived local black hole mass function (BHMF) is in good agreement with existing literature BHMFs. Galaxy demographic projects, including target selection for the Event Horizon Telescope, can benefit from WISE2MBH for up-to-date galaxy parameters and MBH estimates. The WISE2MBH algorithm is publicly available on GitHub.

Context. Extragalactic surveys provide significant statistical data for the study of crucial galaxy parameters (e.g. stellar mass, M*, and star formation rate, SFR) used to constrain galaxy evolution under different environmental conditions. These quantities are derived using manual or automatic methods for galaxy detection and flux measurement in imaging data at different wavelengths. The reliability of these automatic measurements, however, is subject to mis-identification and poor fitting due to the morphological irregularities present in resolved nearby galaxies (e.g. clumps, tidal disturbances, star- forming regions) and its environment (galaxies in overlap). Aims. Our aim is to provide accurate multi-wavelength photometry (from the UV to the IR, including GALEX, SDSS, and WISE) in a sample of ~600 nearby (ɀ < 0.1) isolated mergers, as well as estimations of M, and SFR. Methods. We performed photometry following a semi-automated approach using SExtractor, confirming by visual inspection that we successfully extracted the light from the entire galaxy, including tidal tails and star-forming regions. We used the available SED fitting code MAGPHYS in order to estimate M*, and SFR. Results. We provide the first catalogue of isolated merging galaxies of galaxy mergers including aperture-corrected photometry in 11 bands (FUV, NUV, u, 𝑔, r, i, ɀ, W1, W2, W3, and W4), morphological classification, merging stage, M*, and SFR. We found that SFR and M*, derived from automated catalogues can be wrong by up to three orders of magnitude as a result of incorrect photometry. Conclusions. Contrary to previous methods, our semi-automated method can reliably extract the flux of a merging system completely. Even when the SED fitting often smooths out some of the differences in the photometry, caution using automatic photometry is suggested as these measurements can lead to large differences in M*, and SFR estimations.

We present a stellar dynamical mass measurement of the supermassive black hole in the elliptical (E1) galaxy NGC 3258. Our findings are based on integral field unit spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) observations in narrow-field mode with adaptive optics and the MUSE wide-field mode, from which we extract kinematic information by fitting the Ca ii and Mg b triplets, respectively. Using axisymmetric, three-integral Schwarzschild orbit library models, we fit the observed line-of-sight velocity distributions to infer the supermassive black hole mass, the H -band mass-to-light ratio, the asymptotic circular velocity, and the dark matter halo scale radius of the galaxy. We report a black hole mass of (2.2 ± 0.2) × 10 ^9 M _⊙ at an assumed distance of 31.9 Mpc. This value is in close agreement with a previous measurement from Atacama Large Millimeter/submillimeter Array CO observations. The consistency between these two measurements provides strong support for both the gas dynamical and stellar dynamical methods.