Context. With infrared interferometry it is possible to resolve the nuclear dust distributions that are commonly associated with the dusty torus in active galactic nuclei (AGN). The Circinus galaxy ...hosts the closest Seyfert 2 nucleus and previous interferometric observations have shown that its nuclear dust emission is particularly well resolved. Aims. The aim of the present interferometric investigation is to better constrain the dust morphology in this active nucleus. Methods. To this end, extensive new observations were carried out with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer, leading to a total of 152 correlated flux spectra and differential phases between 8 and 13 μm. To interpret this data, we used a model consisting of black-body emitters with a Gaussian brightness distribution and with dust extinction. Results. The direct analysis of the data and the modelling confirm that the emission is distributed in two distinct components: a disk-like emission component with a size (FWHM) of ~0.2 × 1.1 pc and an extended component with a size of ~0.8 × 1.9 pc. The disk-like component is elongated along PA ~ 46° and oriented perpendicular to the ionisation cone and outflow. The extended component is responsible for 80% of the mid-infrared emission. It is elongated along PA ~ 107°, which is roughly perpendicular to the disk component and thus in polar direction. It is interpreted as emission from the inner funnel of an extended dust distribution and shows a strong increase in the extinction towards the south-east. We find both emission components to be consistent with dust at T ~ 300 K, that is we find no evidence of an increase in the temperature of the dust towards the centre. From this we infer that most of the near-infrared emission probably comes from parsec scales as well. We further argue that the disk component alone is not sufficient to provide the necessary obscuration and collimation of the ionising radiation and outflow. The material responsible for this must instead be located on scales of ~1 pc, surrounding the disk. We associate this material with the dusty torus. Conclusions. The clear separation of the dust emission into a disk-like emitter and a polar elongated source will require an adaptation of our current understanding of the dust emission in AGN. The lack of any evidence of an increase in the dust temperature towards the centre poses a challenge for the picture of a centrally heated dust distribution.
The impact of active galactic nuclei (AGNs) 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 multiphase study of the nuclear environment in the nearby Seyfert galaxy NGC 2110 using the Atacama Large Millimeter/submillimeter Array, Hubble and Spitzer Space Telescopes, and the Very Large Telescope/SINFONI. We identify a region that is markedly weak in low-excitation CO emission from cold molecular gas, but appears to be filled with ionized 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.
BASS. XXII. The BASS DR2 AGN Catalog and Data Koss, Michael J.; Ricci, Claudio; Trakhtenbrot, Benny ...
The Astrophysical journal. Supplement series,
07/2022, Letnik:
261, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract We present the active galactic nucleus (AGN) catalog and optical spectroscopy for the second data release of the Swift BAT AGN Spectroscopic Survey (BASS DR2). With this DR2 release we ...provide 1449 optical spectra, of which 1182 are released for the first time, for the 858 hard-X-ray-selected AGNs in the Swift BAT 70-month sample. The majority of the spectra (801/1449, 55%) are newly obtained from Very Large Telescope (VLT)/X-shooter or Palomar/Doublespec. Many of the spectra have both higher resolution ( R > 2500, N ∼ 450) and/or very wide wavelength coverage (3200–10000 Å, N ∼ 600) that are important for a variety of AGN and host galaxy studies. We include newly revised AGN counterparts for the full sample and review important issues for population studies, with 47 AGN redshifts determined for the first time and 790 black hole mass and accretion rate estimates. This release is spectroscopically complete for all AGNs (100%, 858/858), with 99.8% having redshift measurements (857/858) and 96% completion in black hole mass estimates of unbeamed AGNs (722/752). This AGN sample represents a unique census of the brightest hard-X-ray-selected AGNs in the sky, spanning many orders of magnitude in Eddington ratio ( L / L Edd = 10 −5 –100), black hole mass ( M BH = 10 5 –10 10 M ⊙ ), and AGN bolometric luminosity ( L bol = 10 40 –10 47 erg s −1 ).
Abstract We present measurements of broad emission lines and virial estimates of supermassive black hole masses ( M BH ) for a large sample of ultrahard 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 of 689 AGNs, determined from the H α , H β , Mg ii λ 2798, and/or C iv λ 1549 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 α emission lines in obscured AGNs ( log ( N H / cm − 2 ) > 22.0 ) are on average a factor of 8.0 − 2.4 + 4.1 weaker relative to ultrahard X-ray emission and about 35 − 12 + 7 % narrower than those in unobscured sources (i.e., log ( N H / 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 α but no broad H β ) and/or sources with log ( N H / cm − 2 ) ≳ 22.0 . We provide simple multiplicative corrections for the observed luminosity and width of the broad H α component ( L bH α and FWHMbH α ) in such sources to account for this effect and to (partially) remedy M BH estimates for Type 1.9 objects. As a key ingredient of BASS/DR2, our work provides the community with the data needed to further study powerful AGNs in the low-redshift universe.
Abstract
We present the largest currently existing subarcsecond 3–5
μ
m atlas of 119 local (
z
< 0.3) active galactic nuclei (AGNs). This atlas includes AGNs of five subtypes: 22 are Seyfert 1; five ...are intermediate Seyferts; 46 are Seyfert 2; 26 are low-ionization nuclear emission regions; and 20 are composites/starbursts. Each active galactic nucleus was observed with the Very Large Telescope Infrared Spectrometer and Array Camera (ISAAC) in the
L
and/or
M
bands between 2000 and 2013. We detected at 3
σ
confidence 92 sources in the
L
band and 83 sources in the
M
band. We separated the flux into unresolved nuclear flux and resolved the flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving 3
σ
upper limits for sources that are undetected. Using Wide-field Infrared Survey Explorer (WISE)
W1
- and
W2
-band photometry we derived relations predicting the nuclear
L
and
M
fluxes for Sy1 and Sy2 AGNs 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 the best agreement with the latter. We find that models including polar winds best reproduce the 3–5
μ
m colors, indicating that it is an important component of dusty torus models. We found that several AGNs 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.
Abstract
We present two independent measurements of stellar velocity dispersions (
σ
⋆
) from the Ca
ii
H+K
λ
3969, 3934 and Mg
i
b
λ
5183, 5172, 5167 region (3880–5550 Å) and the calcium triplet ...region (8350–8750 Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs;
z
≤ 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
virial
black hole mass (
M
BH
) estimates and
σ
⋆
measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent
σ
⋆
measurements are highly consistent with each other, with an average offset of only 0.002 ± 0.001 dex. Comparing
M
BH
estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by ≈0.12 dex. Consequently, Eddington ratios estimated through broad-line
M
BH
determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the
M
BH
–
σ
⋆
relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower
M
BH
–
σ
⋆
relation (with a power-law exponent of ≈3.5) compared with that of inactive galaxies (with a power-law exponent of ≈4.5), confirming earlier results obtained from smaller samples.
We examine the near-infrared (NIR) emission from low-luminosity active galactic nuclei (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 data. We find evidence for red continuum components at the center of most galaxies, consistent with the hot dust emission seen in higher-luminosity AGNs. 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 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 rspearman = 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 AGNs. We find that the ratio of NIR to X-ray emission increases toward 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 the James Webb Space Telescope will be a useful tool for detecting the lowest-luminosity AGNs.
In the widely accepted ‘unified model’1 solution of the classification puzzle of active galactic nuclei, the orientation of a dusty accretion torus around the central black hole dominates their ...appearance. In ‘type-1’ systems, the bright nucleus is visible at the centre of a face-on torus. In ‘type-2’ systems the thick, nearly edge-on torus hides the central engine. Later studies suggested evolutionary effects2 and added dusty clumps and polar winds3 but left the basic picture intact. However, recent high-resolution images4 of the archetypal type-2 galaxy NGC 10685,6, suggested a more radical revision. The images displayed a ring-like emission feature that was proposed to be hot dust surrounding the black hole at the radius where the radiation from the central engine evaporates the dust. That ring is too thin and too far tilted from edge-on to hide the central engine, and ad hoc foreground extinction is needed to explain the type-2 classification. These images quickly generated reinterpretations of the dichotomy between types 1 and 27,8. Here we present new multi-band mid-infrared images of NGC 1068 that detail the dust temperature distribution and reaffirm the original model. Combined with radio data ( J.F.G. and C.M.V.I., manuscript in preparation), our maps locate the central engine that is below the previously reported ring and obscured by a thick, nearly edge-on disk, as predicted by the unified model. We also identify emission from polar flows and absorbing dust that is mineralogically distinct from that towards the Milky Way centre.
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