Nearby Active Galactic Nuclei Research Articles

Deficit of Hot Dust in Low-redshift Active Galactic Nuclei

We assemble a broadband spectral energy distribution (SED) ranging from the optical to the mid-infrared of nearby active galactic nuclei (AGNs) at z < 0.4. The SED fitting analysis is performed using semiempirical templates derived from Palomar-Green quasars to classify the sample into normal, warm-dust-deficient (WDD), and hot-dust-deficient (HDD) AGNs. Kolmogorov–Smirnov tests reveal that HDD AGNs exhibit higher AGN luminosity on average than normal and WDD AGNs. The HDD fraction, on the other hand, is only weakly correlated with the black hole mass and inversely correlated with the Eddington ratio. By fixing the other parameters, we conclude that the HDD fraction is primarily connected with the AGN luminosity. This implies that there is a causal connection between the covering factor of the hot dust component and AGN luminosity, possibly due to the sublimation of the innermost dust or the thickening of the intervening gas in the broad-line region. Analysis of the outflow properties traced by the wing of [O iii]λ5007 suggests that outflows may be related to the formation and maintenance of the hot dust component. Finally, we demonstrate through comparison with previous studies that the classification of HDD AGNs requires careful subtraction of the host galaxy light.

X-Ray Properties of Optically Variable Low-mass AGN Candidates

We present an X-ray analysis of 14 nearby (z < 0.044) active galactic nuclei (AGNs) in low-mass galaxies (M * ≲ 5 × 109 M ⊙) selected based on their optical variability. Comparing and contrasting different AGN selection techniques in low-mass galaxies is essential for obtaining an accurate estimate of the active fraction in this regime. We use both new and archival observations from the Chandra X-ray Observatory to search for X-ray point sources consistent with AGNs. Four objects have detected nuclear X-ray emission with luminosities ranging from L 0.5−7 ≈ 3 × 1040 to 9 × 1042 erg s−1 with two more marginal detections. All of the detected galaxies have luminosities exceeding those anticipated from X-ray binaries, and all sources are nuclear, suggesting the X-ray emission in most sources is due to an AGN. These observations demonstrate the success of variability at identifying AGNs in low-mass galaxies. We also explore emission-line diagnostics and discuss the differences in the results of these methods for AGN selection, in particular regarding low-mass and low-metallicity systems.

A Tight Correlation between Millimeter and X-Ray Emission in Accreting Massive Black Holes from

Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGNs) could be created by the same population of electrons that gives rise to the X-ray emission that is ubiquitously observed in accreting black holes. We present the results of a dedicated high-spatial-resolution (∼60–100 mas) Atacama Large Millimeter/submillimeter Array (ALMA) campaign on a volume-limited (<50 Mpc) sample of 26 hard X-ray (>10 keV) selected radio-quiet AGNs. We find an extremely high detection rate (25/26 or ), which shows that nuclear emission at millimeter wavelengths is nearly ubiquitous in accreting SMBHs. Our high-resolution observations show a tight correlation between the nuclear (1–23 pc) 100 GHz and the intrinsic X-ray emission (1σ scatter of 0.22 dex). The ratio between the 100 GHz continuum and the X-ray emission does not show any correlation with column density, black hole mass, Eddington ratio, or star formation rate, which suggests that the 100 GHz emission can be used as a proxy of SMBH accretion over a very broad range of these parameters. The strong correlation between 100 GHz and X-ray emission in radio-quiet AGNs could be used to estimate the column density based on the ratio between the observed 2–10 keV () and 100 GHz (F 100 GHz) fluxes. Specifically, a ratio strongly suggests that a source is heavily obscured (). Our work shows the potential of ALMA continuum observations to detect heavily obscured AGNs (up to an optical depth of one at 100 GHz, i.e., N H ≃ 1027 cm−2), and to identify binary SMBHs with separations <100 pc, which cannot be probed by current X-ray facilities.

Nearby active galactic nuclei and starburst galaxies as sources of the measured UHECRs anisotropy signal

The Pierre Auger and the Telescope Array observatories have measured independent and statistical significant anisotropy in the arrival direction of ultra-high-energy cosmic rays (UHECR). Three hotspot regions with relative excess of events and a dipole signal have been identified in different regions of the sky and energy ranges. In this paper, we investigate the conditions under which these anisotropy signal could be generated by nearby (<23 Mpc) active galactic nuclei (AGN) and/or starburst galaxies (SBG). We studied a wide range of possibilities including injected nuclei (p, He, N, Si, and Fe), three UHECR luminosity proxies and three extragalactic magnetic field models. The results shows that both local AGN and SBG are needed to describe all the anisotropy signal. The contribution of AGN to hotspots and to the generation of the dipole is dominant in most cases. SBG is required only to explain the hotspot measured by the Telescope Array Observatory.

Deep Chandra Observations of NGC 5728: Morphology and Spectral Properties of the Extended X-Ray Emission

Recent deep Chandra observations of nearby Compton-thick (CT) active galactic nuclei (AGNs) have produced surprising results, uncovering extended emission not only in soft X-rays but also in hard emission (>3 keV), challenging the long-held belief that the characteristic hard X-ray continuum and fluorescent Fe K lines are associated with the torus in the standard picture of AGNs. In this work, we present an analysis of our deep (∼261 ks) X-ray Chandra ACIS-S observations of NGC 5728, a nearby (z = 0.00932) CT AGN. We find that the diffuse emission is more extended at lower energies, in the bicone direction out to ∼2 kpc radially, but also significantly extended in the direction of the cross-cone, out to ∼1.4 kpc. Our results suggest that the ratio of detected photons in the cross-cone to the bicone region is ∼16%, below 3 keV, decreasing to 5% for energies 3–6 keV. The nuclear spectrum suggests a low-photoionization phase mixed with a more ionized gas component, while the bicone and cross-cone spectra are dominated by a mix of photoionization and shocked gas emission. A mixture of thermal and photoionization models used to fit the spectra indicates the presence of complex gas interactions, consistent with previous observations of other CT AGNs (e.g., ESO 428-G014).

Extended Hard X-Ray Emission in Highly Obscured AGNs

Kiloparsec-scale hard (>3 keV) X-ray continuum and fluorescent Fe Kα line emission has been recently discovered in nearby Compton-thick (CT) active galactic nuclei (AGNs), which opens new opportunities to improve AGN torus modeling and investigate how the central supermassive black hole interacts with and impacts the host galaxy. Following a pilot Chandra survey of nearby CT AGNs, we present in this paper the results of Chandra spatial analysis of five uniformly selected non-CT but still heavily obscured AGNs to investigate the extended hard X-ray emission by measuring the excess emission counts, excess fractions, and physical scales. Three of these AGNs show extended emission in the 3.0–7.0 keV band detected at >3σ above the Chandra point-spread function with total excess fractions ranging from ∼8% to 20%. The extent of the hard emission ranges from at least ∼250 pc to 1.1 kpc in radius. We compare these new sources with CT AGNs and find that CT AGNs appear to be more extended in the hard band than the non-CT AGNs. Similar to CT AGNs, the amounts of extended hard X-ray emission relative to the total emission of these obscured AGNs are not negligible. Together with other AGNs detected with extended hard X-ray emission in the literature, we further explore potential correlations between the extended hard X-ray component and AGN parameters. We also discuss the implications for torus modeling and AGN feedback. Considering potential contributions from X-ray binaries (XRBs) to the extended emission, we do not see strong XRB contamination in the overall sample.

Observable Signatures of Stellar-mass Black Holes in Active Galactic Nuclei

Stellar-mass black holes (BHs) are predicted to be embedded in the disks of active galactic nuclei (AGNs) due to gravitational drag and in situ star formation. However, clear evidence for AGN disk-embedded BHs is currently lacking. Here, as possible electromagnetic signatures of these BHs, we investigate breakout emission from shocks emerging around Blandford–Znajek jets launched from accreting BHs in AGN disks. We assume that most of the highly super-Eddington flow reaches the BH and produces a strong jet, and the jet produces feedback that shuts off accretion and thus leads to episodic flaring. These assumptions, while poorly understood at present, yield observable consequences that can probe the presence of AGN-embedded BHs as well as the accretion process itself. They predict a breakout emission characterized by luminous thermal emission in the X-ray bands and bright broadband nonthermal emission from the infrared to the gamma-ray bands. The flare duration depends on the BH’s distance r from the central supermassive BH, varying between 103–106 s for r ∼ 0.01–1 pc. This emission can be discovered by current and future infrared, optical, and X-ray wide-field surveys and monitoring campaigns of nearby AGNs.

A Complex Dust Morphology in the High-luminosity AGN Mrk 876

Recent models for the inner structures of active galactic nuclei (AGNs) advocate the presence of a radiatively accelerated dusty outflow launched from the outer regions of the accretion disk. Here, we present the first near-IR variable (rms) spectrum for the high-luminosity nearby AGN Mrk 876. We find that it tracks the accretion disk spectrum out to longer wavelengths than the mean spectrum, due to a reduced dust emission. The implied outer accretion disk radius is consistent with the IR results predicted by a contemporaneous optical accretion disk reverberation mapping campaign, and much larger than the self-gravity radius. The reduced flux variability of the hot dust could either be due to the presence of a secondary constant dust component in the mean spectrum or be introduced by the destructive superposition of the dust and accretion disk variability signals, or be some combination of the two. Assuming thermal equilibrium for optically thin dust, we derive the luminosity-based dust radii for different grain properties, using our measurement of the temperature. We find that in all the cases considered, the values are significantly larger than the dust response time measured by IR photometric monitoring campaigns, with the least discrepancy present relative to the result for a wavelength-independent dust emissivity law, i.e., a blackbody, which is appropriate for large grain sizes. This result can be well explained by assuming a flared disk-like structure for the hot dust.

Jet-induced molecular gas excitation and turbulence in the Teacup

In order to investigate the impact of radio jets on the interstellar medium (ISM) of galaxies hosting active galactic nuclei (AGN), we present subarcsecond-resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) and CO(3-2) observations of the Teacup galaxy. This is a nearby (DL = 388 Mpc) radio-quiet type-2 quasar (QSO2) with a compact radio jet (Pjet ≈ 1043 erg s−1) that subtends a small angle from the molecular gas disc. Enhanced emission line widths perpendicular to the jet orientation have been reported for several nearby AGN for the ionised gas. For the molecular gas in the Teacup, not only do we find this enhancement in the velocity dispersion but also a higher brightness temperature ratio (T32/T21) perpendicular to the radio jet compared to the ratios found in the galaxy disc. Our results and the comparison with simulations suggest that the radio jet is compressing and accelerating the molecular gas, and driving a lateral outflow that shows enhanced velocity dispersion and higher gas excitation. These results provide further evidence that the coupling between the jet and the ISM is relevant to AGN feedback even in the case of radio-quiet galaxies.

Broad-line region in NGC 4151 monitored by two decades of reverberation mapping campaigns – I. Evolution of structure and kinematics

ABSTRACT We report the results of long-term reverberation mapping campaigns of the nearby active galactic nuclei (AGNs) NGC 4151, spanning from 1994 to 2022, based on archived observations of the FAST Spectrograph Publicly Archived Programs and our new observations with the 2.3 m telescope at the Wyoming Infrared Observatory. We reduce and calibrate all the spectra in a consistent way, and derive light curves of the broad H β line and 5100 Å continuum. Continuum light curves are also constructed using public archival photometric data to increase sampling cadences. We subtract the host galaxy contamination using Hubble Space Telescope imaging to correct fluxes of the calibrated light curves. Utilizing the long-term archival photometric data, we complete the absolute flux-calibration of the AGN continuum. We find that the H β time delays are correlated with the 5100 Å luminosities as $\tau _{\rm H\beta }\propto L_{5100}^{0.46\pm 0.16}$. This is remarkably consistent with Bentz et al. (2013)’s global size–luminosity relationship of AGNs. Moreover, the data sets for five of the seasons allow us to obtain the velocity-resolved delays of the H β line, showing diverse structures (outflows, inflows, and discs). Combining our results with previous independent measurements, we find the measured dynamics of the H β broad-line region (BLR) are possibly related to the long-term trend of the luminosity. There is also a possible additional ∼1.86 yr time lag between the variation in BLR radius and luminosity. These results suggest that dynamical changes in the BLR may be driven by the effects of radiation pressure.

Multifrequency VLBI Observations of the M84 Inner Jet/Counterjet

Observational studies of the innermost regions of the edge-on jets in nearby active galactic nuclei (AGN) are crucial to understanding their kinematics and morphology. For the inner jet of the nearby low-luminosity AGN in M84, we present new high-sensitivity observations with very long baseline Interferometry since 2019, as well as archival Very Long Baseline Array observations in 2014. We find that the compact core in M84 has an inverted-to-flat spectrum from 1.5–88 GHz. Based on the turnover frequency of 4.2 ± 0.2 GHz in the spectrum, we estimated a magnetic field strength of 1 ∼ 10 mG and an electron number density of ∼105 cm−3 in the core region. Three inner jet components within ∼3 mas of the core are identified and traced in the images at 22 GHz, whose apparent speeds are 0.11 c, 0.27 c, and 0.32 c, respectively. We calculate the viewing angle of for the inner jet based on the proper motion and the flux ratio of jet to counterjet. A propagating sinusoidal model with a wavelength of ∼3.4 mas is used to fit the helical morphology of the jet extended to 20 mas (∼2.2 × 104 Schwarzschild radii).

Explaining the Moderate UV/X-Ray Correlation in AGN

The UV/optical and X-ray variability of active galactic nuclei (AGN) have long been expected to be well correlated as a result of the X-ray illumination of the accretion disk. Recent monitoring campaigns of nearby AGN, however, found that their X-ray and UV/optical emission are only moderately correlated, challenging the aforementioned paradigm. In this work, we aim to demonstrate that due to the definition of the cross-correlation function, a low UV/X-ray correlation is well expected in the case of an X-ray illuminated accretion disk, when the dynamic variability of the X-ray source is taken into account. In particular, we examine how the variability of the geometric or physical configuration of the X-ray source affects the expected correlation. Variations of the geometric configuration are found to produce a range of UV/X-ray cross correlations, which match well the observed values, while they result in a high correlation between the UV and optical variability, reconciling the observed results with theoretical predictions. We conclude that the detection of a low UV/X-ray correlation does not contradict the assumption of the UV/optical variability being driven by the X-ray illumination of the disk, and we discuss the implications of our results for correlation studies.

Collimation of the Relativistic Jet in the Quasar 3C 273

The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline interferometry (VLBI) observations of the archetypical quasar 3C 273 at 86 GHz, performed with the Global Millimeter VLBI Array, for the first time including the Atacama Large Millimeter/submillimeter Array. Our observations achieve a high angular resolution down to ∼60 μas, resolving the innermost part of the jet ever on scales of ∼105 Schwarzschild radii. Our observations, including close-in-time High Sensitivity Array observations of 3C 273 at 15, 22, and 43 GHz, suggest that the inner jet collimates parabolically, while the outer jet expands conically, similar to jets from other nearby low-luminosity AGNs. We discovered the jet collimation break around 107 Schwarzschild radii, providing the first compelling evidence for structural transition in a quasar jet. The location of the collimation break for 3C 273 is farther downstream from the sphere of gravitational influence (SGI) from the central SMBH. With the results for other AGN jets, our results show that the end of the collimation zone in AGN jets is governed not only by the SGI of the SMBH but also by the more diverse properties of the central nuclei.

BASS XXXII: Studying the Nuclear Millimeter-wave Continuum Emission of AGNs with ALMA at Scales ≲100–200 pc

To understand the origin of nuclear (≲100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed subarcsecond resolution Band-6 (211–275 GHz) Atacama Large Millimeter/submillimeter Array data of 98 nearby AGNs (z < 0.05) from the 70 month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides the largest number of AGNs to date with high mm-wave spatial resolution sampling (∼1–200 pc), and spans broad ranges of 14–150 keV luminosity {}, black hole mass ], and Eddington ratio (). We find a significant correlation between 1.3 mm (230 GHz) and 14–150 keV luminosities. Its scatter is ≈0.36 dex, and the mm-wave emission may serve as a good proxy of the AGN luminosity, free of dust extinction up to N H ∼ 1026 cm−2. While the mm-wave emission could be self-absorbed synchrotron radiation around the X-ray corona according to past works, we also discuss different possible origins of the mm-wave emission: AGN-related dust emission, outflow-driven shocks, and a small-scale (<200 pc) jet. The dust emission is unlikely to be dominant, as the mm-wave slope is generally flatter than expected. Also, due to no increase in the mm-wave luminosity with the Eddington ratio, a radiation-driven outflow model is possibly not the common mechanism. Furthermore, we find independence of the mm-wave luminosity on indicators of the inclination angle from the polar axis of the nuclear structure, which is inconsistent with a jet model whose luminosity depends only on the angle.

BASS XXXVII: The Role of Radiative Feedback in the Growth and Obscuration Properties of Nearby Supermassive Black Holes

We study the relation between obscuration and supermassive black hole (SMBH) accretion using a large sample of hard X-ray selected active galactic nuclei (AGNs). We find a strong decrease in the fraction of obscured sources above the Eddington limit for dusty gas () confirming earlier results, and consistent with the radiation-regulated unification model. This also explains the difference in the Eddington ratio distribution functions (ERDFs) of type 1 and type 2 AGNs obtained by a recent study. The break in the ERDF of nearby AGNs is at . This corresponds to the λ Edd where AGNs transition from having most of their sky covered by obscuring material to being mostly devoid of absorbing material. A similar trend is observed for the luminosity function, which implies that most of the SMBH growth in the local universe happens when the AGN is covered by a large reservoir of gas and dust. These results could be explained with a radiation-regulated growth model, in which AGNs move in the N H–λ Edd plane during their life cycle. The growth episode starts with the AGN mostly unobscured and accreting at low λ Edd. As the SMBH is further fueled, λ Edd, N H and the covering factor increase, leading the AGN to be preferentially observed as obscured. Once λ Edd reaches the Eddington limit for dusty gas, the covering factor and N H rapidly decrease, leading the AGN to be typically observed as unobscured. As the remaining fuel is depleted, the SMBH goes back into a quiescent phase.

Probing the Extent of Fe Kα Emission in Nearby Active Galactic Nuclei Using Multi-order Analysis of Chandra High Energy Transmission Grating Data

We present a study of the narrow Fe Kα line in seven bright, nearby active galactic nuclei (AGN) that have been observed extensively with the Chandra High Energy Transmission Grating (HETG). The HETG data reveal a wider Fe Kα line in the first-order spectrum than in the second- and third-order spectra, which we interpret as the result of spatially extended Fe Kα emission. We utilize these differences in narrow Fe Kα line widths in the multi-order Chandra HETG spectra to determine the spatial extent and intrinsic velocity width of the emitting material in each object. We find that there is modest evidence for spatially extended emission in each object, corresponding to extension of r ∼ 5–100 pc. These distances are significantly larger than those inferred from velocity widths assuming gravitational motions, which give r ∼ 0.01–1 pc. This implies either that the gas is emitting at a range of radii, with smaller radii dominating the velocity width and larger radii dominating the spatial extent, or that the gas is exhibiting nongravitational motions, which we suggest would be outflows due to slight excess redshift in the line and velocities that exceed the freefall velocity. We also use the spatial extent information to estimate the mass of the emitting gas by counting fluorescing iron atoms, finding masses on the order of M gas ∼ 105–108 M ⊙. Future work with observatories like XRISM will be able to extend this study to a larger number of AGN and decrease uncertainties that arise as a result of the low signal-to-noise ratio of the higher-order HETG data.

Unexplored outflows in nearby low luminosity AGNs

Context. Multi-phase outflows play a central role in galaxy evolution shaping the properties of galaxies. Understanding outflows and their effects in low luminosity active galactic nuclei (AGNs), such as low ionisation nuclear emission line regions (LINERs), is essential. LINERs bridge the gap between normal and active galaxies, being the most numerous AGN population in the local Universe. Aims. Our goal is to analyse the kinematics and ionisation mechanisms of the multi-phase gas of NGC 1052, the prototypical LINER, in order to detect and map the ionised and neutral phases of the putative outflow. Methods. We obtained Very Large Telescope MUSE and Gran Telescopio Canarias MEGARA optical integral field spectroscopy data for NGC 1052. In addition to stellar kinematics maps, by modelling spectral lines with multiple Gaussian components, we obtained flux, kinematic, and excitation maps of both ionised and neutral gas. Results. The stars are distributed in a dynamically hot disc (V/σ ∼ 1.2), with a centrally peaked velocity dispersion map (σc = 201 ± 10 km s−1) and large observed velocity amplitudes (ΔV = 167 ± 19 km s−1). The ionised gas, probed by the primary component is detected up to ∼30″ (∼3.3 kpc) mostly in the polar direction with blue and red velocities (∣V∣ &lt; 250 km s−1). The velocity dispersion map shows a notable enhancement (σ &gt; 90 km s−1) crossing the galaxy along the major axis of rotation in the central 10″. The secondary component has a bipolar morphology, velocity dispersion larger than 150 km s−1, and velocities up to 660 km s−1. A third component is detected with MUSE (and barely with MEGARA), but it is not spatially resolved. The broad-line region (BLR) component (used to model the broad Hα emission only) has a full width at half maximum of 2427 ± 332 and 2350 ± 470 km s−1 for MUSE and MEGARA data, respectively. The maps of the NaD absorption indicate optically thick neutral gas with complex kinematics. The velocity field is consistent with a slow rotating disc (ΔV = 77 ± 12 km s−1), but the velocity dispersion map is off-centred without any counterpart in the (centrally peaked) flux map. Conclusions. We found evidence of an ionised gas outflow (secondary component) with a mass of 1.6 ± 0.6 × 105 M⊙, and mass rate of 0.4 ± 0.2 M⊙ yr−1. The outflow is propagating in a cocoon of gas with enhanced turbulence and might be triggering the onset of kiloparsec-scale buoyant bubbles (polar emission), both probed by the primary component. Taking into account the energy and kinetic power of the outflow (1.3 ± 0.9 × 1053 erg and 8.8 ± 3.5 × 1040 erg s−1, respectively) as well as its alignment with both the jet and the cocoon, and that the gas is collisionally ionised (due to gas compression), we consider that the most likely power source of the outflow is the jet, although some contribution from the AGN is possible. The hints of the presence of a neutral gas outflow are weak.

Localizing narrow Fe Kαemission within bright AGN

Context.The 6.4 keV Fe Kαemission line is a ubiquitous feature in X-ray spectra of active galactic nuclei (AGN), and its properties track the interaction between the variable primary X-ray continuum and the surrounding structure from which it arises.Aims.We clarify the nature and origin of the narrow Fe Kαemission using X-ray spectral, timing, and imaging constraints, plus possible correlations to AGN and host galaxy properties, for 38 bright nearby AGN (z &lt; 0.5) from the Burst Alert Telescope AGN Spectroscopic Survey.Methods.ModelingChandraandXMM-Newtonspectra, we computed line full-width half-maxima (FWHMs) and constructed Fe Kαline and 2–10 keV continuum light curves. The FWHM provides one estimate of the Fe Kαemitting region size,RFeKα, assuming virial motion. A second estimate comes from comparing the degree of correlation between the variability of the continuum and line-only light curves, compared to simulated light curves. Finally, we extractedChandraradial profiles to place upper limits onRFeKα.Results.For 90% (21/24) of AGN with FWHM measurements,RFeKαis smaller than the fiducial dust sublimation radius,Rsub. From timing analysis, 37 and 18 AGN show significant continuum and Fe Kαvariability, respectively. Despite a wide range of variability properties, the constraints on the Fe Kαphoton reprocessor size independently confirm thatRFeKαis smaller thanRsubin 83% of AGN. Finally, the imaging analysis yields loose upper limits for all but two sources; notably, the Circinus Galaxy and NGC 1068 show significant but subdominant extended Fe Kαemission out to ∼100 and ∼800 pc, respectively.Conclusions.Based on independent constraints, we conclude that the majority of the narrow Fe Kαemission in typical AGN predominantly arises from regions smaller than and presumably insideRsub, and thus it is associated either with the outer broad line region or outer accretion disk. However, the large diversity of continuum and narrow Fe Kαvariability properties are not easily accommodated by a universal scenario.

Ionized Outflows in Nearby Quasars Are Poorly Coupled to Their Host Galaxies

We analyze Multi-Unit Spectroscopic Explorer observations of nine low-redshift (z < 0.1) Palomar-Green quasar host galaxies to investigate the spatial distribution and kinematics of the warm, ionized interstellar medium, with the goal of searching for and constraining the efficiency of active galactic nucleus (AGN) feedback. After separating the bright AGN from the starlight and nebular emission, we use pixel-wise, kpc-scale diagnostics to determine the underlying excitation mechanism of the line emission, and we measure the kinematics of the narrow-line region (NLR) to estimate the physical properties of the ionized outflows. The radial size of the NLR correlates with the AGN luminosity, reaching scales of ∼5 kpc and beyond. The geometry of the NLR is well-represented by a projected biconical structure, suggesting that the AGN radiation preferably escapes through the ionization cone. We find enhanced velocity dispersions (≳100 km s−1) traced by the Hα emission line in localized zones within the ionization cones. Interpreting these kinematic features as signatures of interaction between an AGN-driven ionized gas outflow and the host galaxy interstellar medium, we derive mass-outflow rates of ∼0.008–1.6 M ⊙ yr−1 and kinetic injection rates of ∼1039–1042 erg s−1, which yield extremely low coupling efficiencies of ≲10−3. These findings add to the growing body of recent observational evidence that AGN feedback is highly ineffective in the host galaxies of nearby AGNs.

BASS. XXVIII. Near-infrared Data Release 2: High-ionization and Broad Lines in Active Galactic Nuclei* * Based on observations collected under programs 086.B-0135(A), 089.B-0951(A), 090.A-0830(A), 091.B-0900(B), 093.A-0766(A), 098.A-0635(B), 099.A-0403(B), 0101.A-0765(A), and 0102.A-0433(A) with X-shooter at the Very Large Telescope of the Paranal Observatory in Chile, operated by the European Southern Observatory.

We present the BAT AGN Spectroscopic Survey (BASS) Near-infrared Data Release 2 (DR2), a study of 168 nearby ( z¯=0.04 , z < 0.6) active galactic nuclei (AGN) from the all-sky Swift Burst Array Telescope X-ray survey observed with the Very Large Telescope (VLT)/X-shooter in the near-infrared (NIR; 0.8–2.4 μm). We find that 49/109 (45%) Seyfert 2 and 35/58 (60%) Seyfert 1 galaxies observed with VLT/X-shooter show at least one NIR high-ionization coronal line (CL; ionization potential χ > 100 eV). Comparing the emission of the [Si vi] λ1.9640 CL with the X-ray emission for the DR2 AGN, we find a significantly tighter correlation, with a lower scatter (0.37 dex) than that for the optical [O iii] λ5007 line (0.71 dex). We do not find any correlation between CL emission and the X-ray photon index Γ. We find a clear trend of line blueshifts with increasing ionization potential in several CLs, such as [Si vi] λ1.9640, [Si x] λ1.4300, [S viii] λ0.9915, and [S ix] λ1.2520, indicating the radial structure of the CL region. Finally, we find a strong underestimation bias in black hole mass measurements of Sy 1.9 using broad Hα due to the presence of significant dust obscuration. In contrast, the broad Paα and Paβ emission lines are in agreement with the M–σ relation. Based on the combined DR1 and DR2 X-shooter sample, the NIR BASS sample now comprises 266 AGN with rest-frame NIR spectroscopic observations, the largest set assembled to date.