We present two independent measurements of stellar velocity dispersions (
$\sigma_\rm{\star}$ ) from the Ca\,H+K \& Mg\,\textsc{i} region
(3880--5550~\AA) and the Calcium Triplet region (CaT, ...8350--8750~\AA) for 173
hard X-ray-selected Type 1 AGNs ($z \leq$ 0.08) from the 105-month Swift-BAT
catalog. We construct one of the largest samples of local Type 1 AGNs that have
both single-epoch (SE) 'virial' black hole mass ($M_\rm{BH}$) estimates and
$\sigma_\rm{\star}$ measurements obtained from high spectral resolution data,
allowing us to test the usage of such methods for SMBH studies. We find that
the two independent $\sigma_\rm{\star}$ measurements are highly consistent with
each other, with an average offset of only $0.002\pm0.001$ dex. Comparing
$M_\rm{BH}$ estimates based on broad emission lines and stellar velocity
dispersion measurements, we find that the former is systematically lower by
$\approx$0.12 dex. Consequently, Eddington ratios estimated through broad-line
$M_\rm{BH}$ determinations are similarly biased (but in the opposite way). We
argue that the discrepancy is driven by extinction in the broad-line region
(BLR). We also find an anti-correlation between the offset from the $M_\rm{BH}$
- $\sigma_\rm{\star}$ relation and the Eddington ratio. Our sample of Type 1
AGNs shows a shallower $M_\rm{BH}$ - $\sigma_\rm{\star}$ relation (with a power
law exponent of $\approx$3.5) compared with that of inactive galaxies (with a
power-law exponent of $\approx$4.5), confirming earlier results obtained from
smaller samples.
The annual meeting of the European Astronomical Society took place in Lyon, France, in 2019, but in 2020 it was held online only due the COVID-19 pandemic. The carbon footprint of the virtual meeting ...was roughly 3,000 times smaller than the face-to-face one, providing encouragement for more ecologically minded conferencing.
We examine the near-infrared (NIR) emission from low-luminosity AGNs (LLAGNs). Our galaxy sample includes 15 objects with detected 2-10 keV X-ray emission, dynamical black hole mass estimates from ...the literature, and available Gemini/NIFS integral field spectroscopy (IFU) data. We find evidence for red continuum components at the center of most galaxies, consistent with the hot dust emission seen in higher luminosity AGN. We decompose the spectral data cubes into a stellar and continuum component, assuming the continuum component comes from thermal emission from hot dust. We detect nuclear thermal emission in 14 out of 15 objects. This emission causes weaker CO absorption lines and redder continuum (\(2.05-2.28\:\mu\)m) in our \(K\)-band data, as expected from hot dust around an AGN. The NIR emission is clearly correlated with the 2-10 keV X-ray flux, with a Spearman coefficient of \(r_{spearman}=0.69\) suggesting a \(>99\%\) significance of correlation, providing further evidence of an AGN origin. Our sample has typical X-ray and NIR fluxes \(3-4\) orders of magnitude less luminous than previous work studying the NIR emission from AGN. We find that the ratio of NIR to X-ray emission increases towards lower Eddington ratios. The NIR emission in our sample is often brighter than the X-ray emission, with our \(K\)-band AGN luminosities comparable to or greater than the 2-10 keV X-ray luminosities in all objects with Eddington ratios below \(0.01\%\). The nature of this LLAGN NIR emission remains unclear, with one possibility being an increased contribution from jet emission at these low luminosities. These observations suggest JWST will be a useful tool for detecting the lowest luminosity AGN.
We use Gemini Near-Infrared Integral Field Spectrograph (NIFS) adaptive optics assisted data-cubes to map the stellar population of the inner few hundred parsecs of a sample of 18 nearby Seyfert ...galaxies. The near-infrared light is dominated by the contribution of young to intermediate old stellar populations, with light-weighted mean ages \(_L\ \lesssim \) 1.5\,Gyr. Hot dust (\(HD\)) emission is centrally peaked (in the unresolved nucleus), but it is also needed to reproduce the continuum beyond the nucleus in nearly half of the sample. We have analysed the stellar population properties of the nuclear region and their relation with more global properties of the galaxies. We find a correlation between the X-ray luminosity and the contributions from the \(HD\), featureless continuum \(FC\) and reddening \(A_V\). We attribute these correlations to the fact that all these properties are linked to the mass accretion rate to the active galactic nuclei (AGN). We also find a correlation of the bolometric luminosity \(log(LBol_{obs})\) with the mass-weighted mean age of the stellar population, interpreted as due a delay between the formation of new stars and the triggering/feeding of the AGN. The gas reaching the supermassive black hole is probably originated from mass loss from the already somewhat evolved intermediate-age stellar population (\(_L \lesssim \) 1.5\,Gyr). In summary, our results show that there is a significant fraction of young to intermediate age stellar populations in the inner few 100\,pc of active galaxies, suggesting that this region is facing a rejuvenation process in which the AGN, once triggered, precludes further star formation, in the sense that it can be associated with the lack of new star formation in the nuclear region.
We present the largest currently existing subarcsecond 3-5 \(\mu\)m atlas of 119 local (\(z < 0.3\)) active galactic nuclei (AGN). This atlas includes AGN of 5 subtypes: 22 are Seyfert 1; 5 are ...intermediate Seyferts; 46 are Seyfert 2; 26 are LINERs; and 20 are composites/starbursts. Each AGN was observed with VLT ISAAC in the \(L\)- and/or \(M\)-bands between 2000 and 2013. We detect at 3\(\sigma\) confidence 92 sources in the \(L\)-band and 83 sources in the \(M\)-band. We separate the flux into unresolved nuclear flux and resolved flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving \(3\sigma\) upper-limits for sources which are undetected. Using WISE W1- and W2-band photometry we derive relations predicting the nuclear \(L\) and \(M\) fluxes for Sy1 and Sy2 AGN based on their W1-W2 color and WISE fluxes. Lastly, we compare the measured mid-infrared colors to those predicted by dusty torus models SKIRTOR, CLUMPY, CAT3D, and CAT3D-WIND, finding best agreement with the latter. We find that models including polar winds best reproduce the 3-5\(\mu\)m colors, indicating that winds are an important component of dusty torus models. We find that several AGN are bluer than models predict. We discuss several explanations for this and find that it is most plausibly stellar light contamination within the ISAAC \(L\)-band nuclear fluxes.
The impact of Active Galactic Nuclei (AGN) on star formation has implications for our understanding of the relationships between supermassive black holes and their galaxies, as well as for the growth ...of galaxies over the history of the Universe. We report on a high-resolution multi-phase study of the nuclear environment in the nearby Seyfert galaxy NGC 2110 using the Atacama Large Millimeter Array (ALMA), Hubble and Spitzer Space Telescopes, and the Very Large Telescope/SINFONI. We identify a region that is markedly weak in low-excitation CO \(2\rightarrow1\) emission from cold molecular gas, but appears to be filled with ionised and warm molecular gas, which indicates that the AGN is directly influencing the properties of the molecular material. Using multiple molecular gas tracers, we demonstrate that, despite the lack of CO line emission, the surface densities and kinematics of molecular gas vary smoothly across the region. Our results demonstrate that the influence of an AGN on star-forming gas can be quite localized. In contrast to widely-held theoretical expectations, we find that molecular gas remains resilient to the glare of energetic AGN feedback.
We aim to shed light on the physical properties and kinematics of the molecular material in the nucleus of one of the closest type 2 active galaxies. To this end, we obtained high angular resolution ...ALMA observations of the nucleus of the Circinus galaxy. The observations map the emission at 350GHz and 690GHz with spatial resolutions of ~3.8pc and ~2.2pc, respectively. The continuum emission traces cold (\(T\lesssim100\)K) dust in a circumnuclear disk with spiral arms on scales of 25pc, plus a marginally resolved nuclear emission peak. The latter is not extended in polar direction as claimed based on earlier ALMA observations. A significant amount (of the order of 40%) of the 350GHz emission is not related to dust, but most likely free-free emission instead. We detect CO(3-2) and CO(6-5) as well as HCO\(^+\)(4-3), HCN(4-3), and CS(4-3). The CO emission is extended, showing a spiral pattern, similar to the extended dust emission. Towards the nucleus, CO is excited to higher transitions and its emission is self-absorbed, leading to an apparent hole in the CO(3-2) but not the CO(6-5) emission. On the other hand, the high gas density tracers HCO\(^+\), HCN, and CS show a strong, yet unresolved ((\(\lesssim4\)pc) concentration of the emission at the nucleus, pointing at a very small 'torus'. The kinematics are dominated by rotation and point at a geometrically thin disk down to the resolution limit of our observations. In contrast to several other AGNs, no HCN enhancement is found towards the nucleus. The Circinus nucleus is therefore composed of at least two distinct components: (1) an optically thin, warm outflow of ionised gas containing clouds of dust; and (2) a cold molecular and dusty disk. These findings support the most recent radiative transfer calculations of the obscuring structures in AGNs, which find a similar two-component structure. (Abridged)
We present measurements of broad emission lines and virial estimates of supermassive black hole masses (\(M_{BH}\)) for a large sample of ultra-hard X-ray selected active galactic nuclei (AGNs) as ...part of the second data release of the BAT AGN Spectroscopic Survey (BASS/DR2). Our catalog includes \(M_{BH}\) estimates for a total 689 AGNs, determined from the H\(\alpha\), H\(\beta\), \(MgII\lambda2798\), and/or \(CIV\lambda1549\) broad emission lines. The core sample includes a total of 512 AGNs drawn from the 70-month Swift/BAT all-sky catalog. We also provide measurements for 177 additional AGNs that are drawn from deeper Swift/BAT survey data. We study the links between \(M_{BH}\) estimates and line-of-sight obscuration measured from X-ray spectral analysis. We find that broad H\(\alpha\) emission lines in obscured AGNs (\(\log (N_{\rm H}/{\rm cm}^{-2})> 22.0\)) are on average a factor of \(8.0_{-2.4}^{+4.1}\) weaker, relative to ultra-hard X-ray emission, and about \(35_{-12}^{~+7}\)\% narrower than in unobscured sources (i.e., \(\log (N_{\rm H}/{\rm cm}^{-2}) < 21.5\)). This indicates that the innermost part of the broad-line region is preferentially absorbed. Consequently, current single-epoch \(M_{BH}\) prescriptions result in severely underestimated (\(>\)1 dex) masses for Type 1.9 sources (AGNs with broad H\(\alpha\) but no broad H\(\beta\)) and/or sources with \(\log (N_{\rm H}/{\rm cm}^{-2}) > 22.0\). We provide simple multiplicative corrections for the observed luminosity and width of the broad H\(\alpha\) component (\(L{\rm b}{\rm H}\alpha\) and FWHMbH\(\alpha\)) in such sources to account for this effect, and to (partially) remedy \(M_{BH}\) estimates for Type 1.9 objects. As key ingredient of BASS/DR2, our work provides the community with the data needed to further study powerful AGNs in the low-redshift Universe.
Active galactic nuclei play a key role in the evolution of galaxies, but their inner workings and physical connection to the host are poorly understood due to a lack of angular resolution. Infrared ...interferometry makes it possible to resolve the circumnuclear dust in the nearby Seyfert 2 galaxy, Circinus. Previous observations have revealed complex structures and polar dust emission but interpretation was limited to simple models. MATISSE makes it possible to image these structures for the first time. We observed the Circinus Galaxy with VLTI/MATISSE, producing 150 correlated flux spectra and 100 closure phase spectra. We reconstructed images in the N-band at ~10 mas resolution. We fit blackbody functions with dust extinction to several aperture-extracted fluxes from the images to produce a temperature distribution of central dusty structures. We find significant substructure in the circumnuclear dust: central unresolved flux of ~0.5 Jy, a thin disk 1.9 pc in diameter oriented along ~45 deg,and a ~4x1.5 pc polar emission extending orthogonal to the disk. The polar emission exhibits patchiness, which we attribute to clumpy dust. Flux enhancements to the east and west of the disk are seen for the first time. We distinguish the temperature profiles of the disk and of the polar emission: the disk shows a steep temperature gradient indicative of denser material; the polar profile is flatter, indicating clumpiness and/or lower dust density. The unresolved flux is fitted with a high temperature, ~370 K. The polar dust remains warm (~200 K) out to 1.5 pc from the disk. The recovered morphology and temperature distribution resembles modeling of accretion disks with radiation-driven winds at large scales, but we placed new constraints on the subparsec dust. The subparsec features imaged here place new constraints on the physical modeling of circumnuclear dust in active galaxies.
PDF