Active Galactic Nuclei Torus Research Articles

Dust in Little Red Dots

JWST has revealed a ubiquitous population of “little red dots” (LRDs) at z ≳ 4, selected via their red rest-frame optical emission and compact morphologies. They are thought to be reddened by dust, whether in tori of active galactic nuclei (AGNs) or the interstellar medium, though none have direct dust detections to date. Informed by the average characteristics of 675 LRDs drawn from the literature, we provide ballpark constraints on the dust characteristics of the LRD population and estimate they have average dust masses of 〈Mdust〉=(1.6−0.9+4.8)×104 M ⊙, luminosities of 〈LIR〉=(8−5+3)×1010 L ⊙, and temperatures of 〈Tdust〉=110−36+21 K. Notably, the spectral energy distributions are thought to peak at ∼100 K (rest-frame 20–30 μm) regardless of heating mechanism, whether AGN or star formation. LRDs’ compact sizes R eff ∼ 100 pc are the dominant factor contributing to their low estimated dust masses. Our predictions likely mean LRDs have, on average, a submillimeter emission factor of ∼100× fainter than current Atacama Large Millimeter/submillimeter Array limits provide. The star-to-dust ratio is a factor ∼100× larger than expected from dust formation models if one assumes the rest-optical light is dominated by stars; this suggests stars do not dominate. Despite their high apparent volume density, LRDs contribute negligibly (0.1%) to the cosmic dust budget at z ≳ 4 due to their low dust masses.

JADES - The Rosetta Stone of JWST-discovered AGN: deciphering the intriguing nature of early AGN

Abstract JWST has discovered a large population of Active Galactic Nuclei (AGN) at high redshift, which are weak in the X-rays. Here we present the NIRSpec spectrum of the most extreme of these objects, GN-28074, an AGN at z = 2.26 with prominent hydrogen and He i broad lines, and with the highest limit on the bolometric to X-ray luminosity ratio among all spectroscopically confirmed AGN in GOODS. This source is also characterized by a mid-IR excess, likely associated with the AGN torus’ hot dust. The high bolometric luminosity and moderate redshift of this AGN allow us to explore its properties more in depth relative to other JWST-discovered AGN. The NIRSpec spectrum reveals prominent, slightly blueshifted absorption of Hα, Hβ and He i λ10830. The Balmer absorption lines require gas with densities of nH > 108 cm−3, consistent with clouds in the Broad Line Region (BLR). This finding suggests that part of the X-ray weakness is due to high (Compton thick) X-ray absorption by clouds in the BLR, or in its outer regions. GN-28074 is also extremely radio-weak. The radio weakness can also be explained in terms of absorption, as the inferred density of the BLR clouds makes them attenuate the radio emission through free-free absorption. Alternatively, the nuclear magnetic field may be underdeveloped, resulting both in intrinsically weak radio emission and lack of hot corona, hence intrinsic X-ray weakness. Finally, we show that recently proposed scenarios, invoking hyper-dense outflows or Raman scattering to explain the broad Hα, are ruled out.

Exploring the properties of the obscured hyperluminous quasar COS-87259 at z = 6.853

ABSTRACT In this paper we explore the properties of the $z=6.853$ obscured hyperluminous quasar COS-87259, discovered in the Cosmological Evolution Survey (COSMOS) field, with our recently developed Bayesian spectral energy distribution (SED) fitting code SMART (Spectral energy distributions Markov chain Analysis with Radiative Transfer models). SMART fits SEDs exclusively with multicomponent radiative transfer models that constitute four different types of pre-computed libraries for the active galactic nucleus (AGN) torus, the starburst, and the spheroidal or disc host. We explore two smooth radiative transfer models for the AGN torus and two two-phase models, in order to put constraints on the AGN fraction of the galaxy, the black hole mass, and its star formation rate (SFR). We find that either of the smooth tapered disc or the two-phase flared disc models provide a good fit to the SED of COS-87259. The best-fitting models predict an AGN fraction in the range $86-92$ per cent, a bolometric AGN luminosity of $5.8-10.3 \times 10^{13} L_\odot$, a black hole mass of $1.8-3.2 \times 10^{9} M_\odot$ (assuming the quasar is accreting at the Eddington limit), and an SFR in the range $1985-2001~M_\odot \rm yr^{-1}$. The predicted space density of such objects in the redshift range $4-7$ is $\sim 20$ times more than that of co-eval unobscured quasars.

X-ray polarisation in AGN circumnuclear media

Context. Cold gas and dust reprocess the central X-ray emission of active galactic nuclei (AGN), producing characteristic spectro-polarimetric features in the X-ray band. The recent launch of IXPE allows for observations of this X-ray polarisation signal, which encodes unique information on the parsec-scale circumnuclear medium of obscured AGN. However, the models for interpreting these polarimetric data are under-explored and do not reach the same level of sophistication as the corresponding spectral models. Aims. We aim at closing the gap between the spectral and spectro-polarimetric modelling of AGN circumnuclear media in the X-ray band by providing the tools for simulating X-ray polarisation in complex geometries of cold gas alongside X-ray spectra. Methods. We lay out the framework for X-ray polarisation in 3D radiative transfer simulations and provide an implementation to the 3D radiative transfer code SKIRT, focussing on (de)polarisation due to scattering and fluorescent re-emission. As an application, we explored the spectro-polarimetric properties of a 2D toroidal reprocessor of cold gas, modelling the circumnuclear medium of AGN. Results. For the 2D torus model, we find a complex behaviour of the polarisation angle with photon energy, which we interpret as a balance between the reprocessed photon flux originating from different sky regions, with a direct link to the torus geometry. We calculated a large grid of AGN torus models and demonstrated how spatially resolved X-ray polarisation maps could form a useful tool for interpreting the geometrical information that is encoded in IXPE observations. With this work, we release high-resolution AGN torus templates that simultaneously describe X-ray spectra and spectro-polarimetry for observational data fitting with XSPEC. Conclusions. The SKIRT code can now model X-ray polarisation simultaneously with X-ray spectra and provide synthetic spectro-polarimetric observations for complex 3D circumnuclear media, with all features of the established SKIRT framework available.

Dust beyond the torus: revealing the mid-infrared heart of local Seyfert ESO 428-G14 with JWST/MIRI

ABSTRACT Polar dust has been discovered in a number of local active galactic nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST/MIRI study aimed at imaging polar dust by zooming on to the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionized by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to $r\approx 100 \, \rm pc$. We estimate the emitting dust has a temperature of $\sim 120\, \rm K$. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies.

Active galactic nucleus X-ray luminosity function and absorption function in the Early Universe (3 ≤ z ≤ 6)

The X-ray luminosity function (XLF) of active galactic nuclei (AGN) offers a robust tool to study the evolution and the growth of the supermassive black-hole population over cosmic time. Owing to the limited area probed by X-ray surveys, optical surveys are routinely used to probe the accretion in the high-redshift Universe z ≥ 3. However, optical surveys may be incomplete because they are strongly affected by dust redenning. In this work we derive the XLF and its evolution at high redshifts (z ≥ 3) using a large sample of AGN selected in different fields with various areas and depths covering a wide range of luminosities. Additionally, we put the tightest yet constraints on the absorption function in this redshift regime. In particular, we used more than 600 soft X-ray selected (0.5 − 2 keV) high-z sources in the Chandra deep fields, the Chandra COSMOS Legacy survey, and the XMM-XXL northern field. We derived the X-ray spectral properties for all sources via spectral fitting, using a consistent technique and model. To model the parametric form of the XLF and the absorption function, we used a Bayesian methodology, allowing us to correctly propagate the uncertainties for the observed X-ray properties of our sources and also the absorption effects. The evolution of XLF is in agreement with a pure density evolution model similar to what is witnessed at optical wavelengths, although a luminosity-dependent density evolution model cannot be securely ruled out. A large fraction (∼60%) of our sources are absorbed by column densities of NH ≥ 1023 cm−2, while ∼17% of the sources are Compton-Thick. Our results favour a scenario where both the interstellar medium of the host and the AGN torus contribute to the obscuration. The derived black hole accretion rate density is roughly in agreement with the large-scale cosmological hydrodynamical simulations, if one takes into account the results that the X-ray AGN are hosted by massive galaxies, while it differs from that derived using JWST data. The latter could be due to the differences in the AGN and host-galaxy properties.

Probing the Subparsec Dust of a Supermassive Black Hole with the Tidal Disruption Event AT 2020mot

AT 2020mot is a typical UV/optical tidal disruption event (TDE) with no radio or X-ray signatures in a quiescent host. We find an i-band excess and rebrightening along the decline of the light curve which could be due to two consecutive dust echoes from the TDE. We model our observations following van Velzen et al. and find that the near-infrared light curve can be explained by concentric rings of thin dust within ∼0.1 pc of a ∼6 × 106 M ⊙ supermassive black hole (SMBH), among the smallest scales at which dust has been inferred near SMBHs. We find dust covering factors of order f c ≤ 2%, much lower than found for dusty tori of active galactic nuclei. These results highlight the potential of TDEs for uncovering the environments around black holes when including near-infrared observations in high-cadence transient studies.

Dust dynamics in AGN winds: a new mechanism for multiwavelength AGN variability

ABSTRACT Partial dust obscuration in active galactic nuclei (AGNs) has been proposed as a potential explanation for some cases of AGN variability. The dust–gas mixture present in AGN tori is accelerated by radiation pressure, leading to the launching of an AGN wind. Dust under these conditions has been shown to be unstable to a generic class of fast-growing resonant drag instabilities (RDIs). In this work, we present the first numerical simulations of radiation-driven outflows that explicitly include dust dynamics in conditions resembling AGN winds. We investigate the implications of RDIs on the torus morphology, AGN variability, and the ability of radiation to effectively launch a wind. We find that the RDIs rapidly develop, reaching saturation at times much shorter than the global time-scales of the outflows, resulting in the formation of filamentary structure on box-size scales with strong dust clumping and super-Alfvénic velocity dispersions. The instabilities lead to fluctuations in dust opacity and gas column density of 10–20 per cent when integrated along mock observed lines of sight to the quasar accretion disc. These fluctuations occur over year to decade time-scales and exhibit a red-noise power spectrum commonly observed for AGNs. Additionally, we find that the radiation effectively couples with the dust–gas mixture, launching highly supersonic winds that entrain 70–90 per cent of the gas, with a factor of ≲3 photon momentum loss relative to the predicted multiple-scattering momentum loading rate. Therefore, our findings suggest that RDIs play an important role in driving the clumpy nature of AGN tori and generating AGN variability consistent with observations.

The role of grain size in active galactic nuclei torus dust models

Context. Active galactic nuclei (AGN) are surrounded by dust within the central parsecs. The dusty circumnuclear structures, referred to as the torus, are mainly heated by radiation from the AGN and emitted at infrared wavelengths, producing the emergent dust continuum and silicate features. Fits to the infrared spectra from the nuclear regions of AGN can place constraints on the dust properties, distribution, and geometry by comparison with models. However, none of the currently available models fully describe the observations of AGN currently available. Aims. Among the aspects least explored, here we focus on the role of dust grain size. We offer the community a new spectral energy distribution (SED) library which is based on the two-phase torus model developed before with the inclusion of the grain size as a model parameter, parameterized by the maximum grain size Psize or equivalently the mass-weighted average grain size ⟨P⟩. Methods. We created 691 200 SEDs using the SKIRT code, where the maximum grain size can vary within the range Psize = 0.01 − 10.0 μm (⟨P⟩ = 0.007 − 3.41 μm). We fit this new library and several existing libraries to a sample of 68 nearby and luminous AGN with Spitzer/IRS spectra dominated by AGN-heated dust. Results. We find that the GoMar23 model can adequately reproduce up to ∼85–88% of the spectra. The dust grain size parameter significantly improves the final fit in up to 90% of these spectra. Statistical tests indicate that the grain size is the third most important parameter in the fitting procedure (after the size and half opening angle of the torus). The requirement of a foreground extinction by our model is lower compared to purely clumpy models. We find that ∼41% of our sample requires that the maximum dust grain size is as large as Psize ∼ 10 μm (⟨P⟩∼3.41 μm). Nonetheless, we also remark that disk+wind and clumpy torus models are still required to reproduce the spectra of a nonnegligible fraction of objects, suggesting the need for several dust geometries to explain the infrared continuum of AGN. Conclusions. This work provides tentative evidence for dust grain growth in the proximity of the AGN.

A decade of near-infrared variability in NGC4388: insights into the AGN structure

ABSTRACT Variability studies have proven to be a powerful diagnostic tool for understanding the physics and properties of active galactic nuclei (AGNs). They provide insights into the spatial and temporal distribution of the emitting regions, the structure and dynamics of the accretion disc, and the properties of the central black hole. Here, we have analysed the K-band spectral variability of the Seyfert 1.9/2 galaxy NGC 4388 spanning five epochs over a period of 10 yr. We have performed spectral synthesis of the nuclear region and found that the contribution of warm dust (T ∼ 800 K) declined by 88 per cent during these 10 yr. In the same period, the [Ca viii] coronal line decreased 61 per cent, whereas Br γ emission declined 35 per cent. For the He i and H2, we did not detect any significant variation beyond their uncertainties. Based on the time span of these changes, we estimate that the region where the warm dust is produced is smaller than 0.6 pc, which suggests that this spectral feature comes from the innermost part of the region sampled, directly from the AGN torus. On the other hand, the bulk of [Ca viii] is produced in the inner ∼2 pc and the nuclear Br γ region is more extended, spanning a region larger than 3 pc. Lastly, He i and H2 are even more external, with most of the emission probably being produced in the host galaxy rather than in the AGN. This is the first spectroscopic variability study in the near-infrared for an AGN where the central source is not directly visible.

Constraining AGN Torus Sizes with Optical and Mid-infrared Ensemble Structure Functions

We propose a new method to constrain the size of the dusty torus in broad-line active galactic nuclei (AGNs) using optical and mid-infrared (MIR) ensemble structure functions (SFs). Because of the geometric dilution of the torus, the MIR response to optical continuum variations has suppressed variability with respect to the optical that depends on the geometry (e.g., size, orientation, opening angle) of the torus. More extended tori have steeper MIR SFs with respect to the optical SFs. We demonstrate the feasibility of this SF approach using simulated AGN light curves and a geometric torus model. While it is difficult to use SFs to constrain the orientation and opening angle due to the insensitivity of the SF on these parameters, the size of the torus can be well determined. Applying this method to the ensemble SFs measured for 587 SDSS quasars, we measure a torus R–L relation of in the WISE W1 band and sizes ∼1.4 times larger in the W2 band, which are in good agreement with dust reverberation mapping measurements. Compared with the reverberation mapping technique, the SF method is much less demanding in data quality and can be applied to any optical+MIR light curves for which a lag measurement may not be possible, as long as the variability process and torus structure are stationary. While this SF method does not extract all information contained in the light curves (i.e., the transfer function), it provides an intuitive interpretation for the observed trends of AGN MIR SFs compared with optical SFs.

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.

Disentangling the AGN and Star formation Contributions to the Radio–X-Ray Emission of Radio-loud Quasars at 1 < Z < 2

We constrain the emission mechanisms responsible for the prodigious electromagnetic output generated by active galactic nuclei (AGNs) and their host galaxies with a novel state-of-the-art AGN radio-to-X-ray spectral energy distribution model fitting code (ARXSED). ARXSED combines multiple components to fit the spectral energy distributions (SEDs) of AGNs and their host galaxies. Emission components include radio structures such as lobes and jets, infrared emission from the AGN torus, visible-to-X-ray emission from the accretion disk, and radio-to-ultraviolet emission from the host galaxy. Applying ARXSED to the radio SEDs of 20 3CRR quasars at 1 < z < 2 verifies the need for more than a simple power law when compact radio structures are present. The nonthermal emission contributes 91%–57% of the observed-frame 1.25 mm to 850 μm flux, and this component must be accounted for when using these wavelengths to estimate star formation properties. We predict the presence of strong radio-linked X-ray emission in more than half the sample sources. ARXSED estimates median (and the associated first and third quartile ranges) BH mass of , logarithm of Eddington ratio of , and spin of for our sample. The inferred AGN torus and accretion disk parameters agree with those estimated from spectroscopic analyses of similar samples in the literature. We present the median intrinsic SED of the luminous radio-loud quasars at 1 < z ≲ 2; this SED represents a significant improvement in the way each component is modeled.

Ray-tracing Simulations and Spectral Models of X-Ray Radiation in Dusty Media

Dust can play an important role in shaping the X-ray spectra and images of astrophysical sources. In this work we report on the implementation of dust in the ray-tracing platform RefleX. We illustrate the different effects associated with the interaction between X-ray photons and dust grains, such as dust scattering, near-edge X-ray absorption fine structures, and shielding. We show how the cross sections of the photon–gas interaction change depending on the fraction of metals in dust grains (i.e., the dust depletion factor). We compare RefleX simulations to the most widely used absorption model that includes dust and show how X-ray spectra are affected by the presence of dust in the absorbing/reprocessing medium for different geometries. We also show how RefleX can be used to reproduce the dust scattering halos observed in Galactic sources, and we release the first torus X-ray spectral model that considers dust absorption and scattering (RXTorusD), to reproduce the spectra of active galactic nuclei (AGNs). RXTorusD also considers other physical processes that are not included in the most widely used AGN torus models, such as Rayleigh scattering and scattering on molecular gas, which can lead to remarkable differences in the predicted X-ray spectra for the same set of geometrical and physical parameters.

NuSTAR Observations of a Heavily X-Ray-obscured AGN in the Dwarf Galaxy J144013+024744

We present a multiwavelength analysis of the dwarf Seyfert 2 galaxy J144013+024744, a candidate obscured active galactic nucleus (AGN) thought to be powered by an intermediate-mass black hole (IMBH, M • ≈ 104−106 M ⊙) of mass M • ∼ 105.2 M ⊙. To study its X-ray properties, we targeted J144013+024744 with NuSTAR for ≈100 ks. The X-ray spectrum was fitted with an absorbed power law, Pexmon, and a physical model (RXTorus). A Bayesian X-ray analysis was performed to estimate the posteriors. The phenomenological and the physical models suggest the AGN to be heavily obscured by a column density of N H = (3.4–7.0) × 1023 cm−2. In particular, the RXTorus model with a subsolar metallicity suggests the obscuring column to be almost Compton-thick. We compared the 2–10 keV intrinsic X-ray luminosity with the inferred X-ray luminosities based on empirical scaling relations for unobscured AGNs using L [Oiv] 25.89 μm, L [Oiii] λ5007, and L 6μm and found that the high-excitation [Oiv] line provides a better estimate of the intrinsic 2–10 keV X-ray luminosity ( erg s−1). Our results suggest that J144013+024744 is the first type 2 dwarf galaxy that shows X-ray spectroscopic evidence for obscuration. The column density that we estimated is among the highest measured to date for IMBH-powered AGNs, implying that a typical AGN torus geometry might extend to the low-mass end. This work has implications for constraining the BH occupation fraction in dwarf galaxies using X-ray observations.

X-ray absorption and reprocessing in the z ∼ 2.5 lensed quasar 2MASS J1042+1641

ABSTRACT We present new broad-band X-ray observations of the z ∼ 2.5 lensed quasar 2MASS J1042+1641, combining XMM–Newton, Chandra, and NuSTAR to provide coverage of the X-ray spectrum over the 0.3–40 keV bandpass in the observed frame, corresponding to the ∼1–140 keV band in the rest frame of 2MASS J1042+1641. The X-ray data show clear evidence for strong (but still Compton-thin) X-ray absorption, NH ∼ 3–4 × 1023 $\rm \, cm^{-2}$, in addition to significant reprocessing by Compton-thick material that must lie away from our line of sight to the central X-ray source. We test two different interpretations for the latter: first that the reprocessing occurs in a classic active galactic nucleus torus, as invoked in unification models, and second that the reprocessing occurs in the accretion disc. Both models can successfully reproduce the observed spectra, and both imply that the source is viewed at moderately low inclinations (i &amp;lt; 50°) despite the heavy line-of-sight absorption. Combining the X-ray data with infrared (IR) data from WISE, the results seen from 2MASS J1042+1641 further support the recent suggestion that large X-ray and IR surveys may together be able to identify good lensed quasar candidates in advance of detailed imaging studies.

On Planet Formation around Supermassive Black Holes and Grain Disruption Barriers by Radiative Torques

It has recently been suggested that planets can form by dust coagulation in the tori of active galactic nuclei (AGN) with low luminosities of L bol ≲ 1042 erg s−1, constituting a new class of exoplanets orbiting supermassive black holes called blanets. However, large dust grains in the AGN torus may be rotationally disrupted by the radiative torque disruption (RATD) mechanism due to AGN radiation feedback, which would prevent blanet formation. To test this scenario, we adopt a simple smooth and a clumpy dust/gas distribution inside the torus region to study the effect of RATD on the evolution of composite dust grains in the midplane of the torus. We found that grain growth and then blanet formation are possible in the smooth torus model. However, in the clumpy torus model, grain growth will be strongly constrained by RATD, assuming the gas density distribution as adopted by Wada et al. We also found that icy grain mantles inside clumps are quickly detached from the grain cores by rotational desorption, reducing the sticking coefficient between icy grains and the coagulation efficiency. The grain rotational disruption and ice desorption occur on timescales much shorter than the growth time up to a factor of ∼104, which are the new barriers that grain growth must overcome to form blanets. Further studies with more realistic AGN models are required to constrain better the effect of RATD on grain growth and blanet formation hypothesis around low-luminosity AGN.

Probing Dynamics and Thermal Properties Inside Molecular Tori with CO Rovibrational Absorption Lines

A recent hydrodynamic model, the radiation-driven fountain model (Wada et al. 2016), presented a dynamical picture that active galactic nuclei (AGNs) tori sustain their geometrical thickness by gas circulation around AGNs, and previous papers have confirmed that this picture is consistent with multiwavelength observations of nearby Seyfert galaxies. Recent near-infrared observations implied that CO rovibrational absorption lines (ΔJ = ± 1, v = 0 − 1, λ ∼ 4.7 μm) could probe the physical properties of the inside tori. However, the origin of the CO absorption lines has been under debate. In this paper, we investigate the origin of the absorption lines and conditions for detecting them by performing line radiative transfer calculations based on the radiation-driven fountain model. We find that CO rovibrational absorption lines are detected at inclination angles θ obs = 50°–80°. At the inclination angle θ obs = 77°, we observe multi-velocity components: inflow (v LOS = 30 km s−1), systemic (v LOS = 0 km s−1), and outflows (v LOS = −75, − 95, and −105 km s−1). The inflow and outflow components (v LOS = 30 and −95 km s−1) are collisionally excited at the excitation temperatures of 186 and 380 K up to J = 12 and 4, respectively. The inflow and outflow components originate from the accreting gas on the equatorial plane at 1.5 pc from the AGN center and the outflowing gas driven by AGN radiation pressure at 1.0 pc, respectively. These results suggest that CO rovibrational absorption lines can provide us with the velocities and kinetic temperatures of the inflow and outflow in the inner few parsec region of AGN tori, and the observations can probe the gas circulation inside the tori.

Discovery of ATLAS17jrp as an Optical-, X-Ray-, and Infrared-bright Tidal Disruption Event in a Star-forming Galaxy

We hereby report the discovery of ATLAS17jrp as an extraordinary tidal disruption event (TDE) in the star-forming galaxy SDSS J162034.99+240726.5 in our recent sample of mid-infrared outbursts in nearby galaxies. Its optical/UV light curves rise to a peak luminosity of ∼1.06 × 1044 erg s−1 in about a month and then decay as t −5/3 with a roughly constant temperature around 19,000 K, and the optical spectra show a blue continuum and very broad Balmer lines with FWHM ∼ 15,000 km s−1, which gradually narrowed to 1400 km s−1 within 4 yr, all agreeing well with other optical TDEs. A delayed and rapidly rising X-ray flare with a peak luminosity of ∼1.27 × 1043 erg s−1 was detected ∼170 days after the optical peak. The high MIR luminosity of ATLAS17jrp (∼2 × 1043 erg s−1) has revealed a distinctive dusty environment with a covering factor as high as ∼0.2, which is comparable to that of a torus in active galactic nuclei but at least one order of magnitude higher than normal optical TDEs. Therefore, ATLAS17jrp turns out to be one of the rare unambiguous TDEs found in star-forming galaxies, and its high dust-covering factor implies that dust extinction could play an important role in the absence of optical TDEs in star-forming galaxies.

The Black Hole–Galaxy Connection: Interplay between Feedback, Obscuration, and Host Galaxy Substructure

Abstract There is growing evidence for physical influence between supermassive black holes and their host galaxies. We present a case study of the nearby galaxy NGC 7582, for which we find evidence that galactic substructure plays an important role in affecting the collimation of ionized outflows as well as contributing to the heavy active galactic nucleus (AGN) obscuration. This result contrasts with a simple, small-scale AGN torus model, according to which AGN-wind collimation may take place inside the torus itself, at subparsec scales. Using 3D spectroscopy with the Multi Unit Spectroscopic Explorer instrument, we probe the kinematics of the stellar and ionized gas components as well as the ionization state of the gas from a combination of emission-line ratios. We report for the first time a kinematically distinct core (KDC) in NGC 7582, on a scale of ∼600 pc. This KDC coincides spatially with dust lanes and starbursting complexes previously observed. We interpret it as a circumnuclear ring of stars and dusty, gas-rich material. We obtain a clear view of the outflowing cones over kiloparsec scales and demonstrate that they are predominantly photoionized by the central engine. We detect the back cone (behind the galaxy) and confirm previous results of a large nuclear obscuration of both the stellar continuum and H ii regions. While we tentatively associate the presence of the KDC with a large-scale bar and/or a minor galaxy merger, we stress the importance of gaining a better understanding of the role of galaxy substructure in controlling the fueling, feedback, and obscuration of AGNs.