arXiv subjects

Miguel Pereira-Santaella

Publications and source records attributed to Miguel Pereira-Santaella.

At least 19 recordsLinked to original sources

arXiv2026

GA-NIFS: sRMS, a new method for disentangling resolved and unresolved emission in integral field spectroscopy. Application to distant quasars

The interpretation of AGN emission-line profiles in type1 AGN is often complicated by the dominance of bright, spatially unresolved nuclear continuum and broad-line region (BLR) emission over narrower and blended components from the narrow-line region (NLR) and the host galaxy. This remains challenging even with integral-field spectroscopy (IFS), as the relevant spatial variations can occur on scales smaller than the angular resolution, particularly in the compact host of distant AGN. We introduce the spatial root-mean-square (sRMS) technique, a new approach to analyse single-epoch IFS that uses the spatial variance of spectra extracted from partially overlapping apertures to isolate off-nuclear emission of high-z BL-AGN, and investigate whether the resulting kinematic information can improve the decomposition of their integrated spectra. We construct sRMS spectra from ensembles of overlapping apertures centred on the unresolved nucleus. Emission that is spatially invariant on the scales probed by the apertures is consequently suppressed, whereas spatially varying emission is retained. We apply the procedure to JWST/NIRSpec data of two z~6.5 QSOs. We model the resulting sRMS spectra with multiple Gaussian components to determine the kinematics of the spatially varying emission, and use these kinematic constraints to model the integrated spectra. The sRMS technique identifies spatially varying narrow-line emission on scales up to ~5x smaller than the NIRSpec PSF and provides robust constraints on the kinematics of individual kinematic components. Imposing these kinematic constraints on the integrated-spectrum fit reduces significantly the degeneracy of multi-component decompositions. Simulations further demonstrate the potential of the method to detect spatially offset BLR emission from close dual BL-AGN, down to projected separations of ~200 pc at z~6.5 for a BLR flux ratio of ~10.

astro-ph.GA↗

arXiv2026

Breaking the Blend: A multi-tracer kinematic decomposition method for IFS data applied to disentangling the AGN outflow and circumnuclear ring in NGC 5728 with JWST

Integral field spectroscopy (IFS) of the central kiloparsecs of active galactic nuclei (AGN) reveals a mixture of spatially coincident emission from star-formation and AGN feedback exciting the interstellar medium. Disentangling these components remains a challenge, as most spectral tracers are affected by both processes, limiting robust interpretation of kinematics and energetics. We present a new framework for decomposing IFS data into distinct components on a spaxel-by-spaxel basis using a multi-tracer, stacked kinematics approach. This method combines kinematic modelling with imposed flux decomposition per spaxel, quantifying the contribution of each component across the field of view. We apply this method to JWST IFS observations of the Seyfert galaxy NGC 5728 from the Galaxy Activity, Torus, and Outflow Survey (GATOS), analysing twelve mid-infrared fine-structure lines (4.49 < $λ$ < 25.89 $μ$m, 7.9 < IP < 126.2 eV). We find that the circumnuclear emission can be decomposed into two dominant components: a star-forming ring and an AGN-driven biconical outflow. Our method separates these structures and recovers their detailed spatial morphology. This framework provides a general and scalable method for physically motivated component separation in IFS data, applicable across many wavelength ranges and targets, enabling reliable interpretation of complex emission line structures (or morphologies) in active galaxies and beyond.

astro-ph.GA↗

arXiv2026

GATOS XV: A JWST/MIRI survey of extended circumnuclear dust emission in nearby Seyfert galaxies

The subarcsecond angular resolution and stable background of JWST has given us the first high-fidelity images of the arcsecond-scale environment around Active Galactic Nuclei (AGNs) in the nearby Universe. With mid-infrared (MIR) surface brightness sensitivities that are much deeper than the best ground-based instruments, the Mid-InfraRed Instrument imager (MIRIM) now allows us to understand the structure and thermal properties of dust using information over wavelengths of $5$-$25$ $μ$m, almost all of the MIR range. We present a Cycle 1 JWST MIRIM survey of Seyfert galaxies with the express aim of characterising AGN-heated dust in the central few 100 pcs, and searching for signatures of dust-laden nuclear outflows. This paper outlines the motivation behind the programme, the data reduction and analysis techniques used to isolate the nuclear and extended emission, and a comparison of the observed MIR structures with those seen in other phases (stars, ionised and molecular gas, absorbing dust). In concert with earlier studies that used these data, we conclude that resolved AGN-heated dust is widespread in the Seyfert population, extending out to a few hundred pcs from the nucleus and often displaying a higher surface-brightness compared to the more widespread star-forming dusty circumnuclear disk. Even after accounting for contamination from emission lines in the MIRI filters, we find strong spatial correlations between MIR dust emission and the AGN-ionised gas in the narrow-line region (NLR).

astro-ph.GA↗

arXiv2026

GATOS: Distinct Feedback Modes in AGN Central Regions Revealed by Spatially Resolved JWST Spectroscopy

This manuscript presents JWST MIRI/MRS observations of the central $r \approx 40-240$ pc regions of five active galactic nuclei (AGN) spanning a wide range of luminosities (${\rm log}\,L_{\rm bol}/{\rm erg\,s^{-1}} \approx 39.8-43.8$). Combining multiphase diagnostics from polycyclic aromatic hydrocarbons (PAHs), molecular hydrogen (H$_2$), and ionized gas at spatial scales of $\sim 4-24$ pc, this study presents a spatially resolved investigation into the effects of the two distinct AGN feedback modes--radiative and kinetic--on the surrounding medium. The results indicate that these two feedback modes, associated with AGN irradiation and shock processing, respectively, collectively drive the relative suppression of PAH emission in the nuclear regions of the targets studied here. Moreover, the coexistence of these two AGN feedback modes, especially the shock processing associated with either jets or outflows, in the central regions of AGN naturally explains both the bimodal distribution of PAH band ratios observed in the targets studied here and the seemingly disparate results reported in the literature. Although based on a limited sample, these findings provide new insights into calibrating star-formation rates (SFRs) from PAH emission in AGN, and more importantly, lay the groundwork for a practical framework to diagnose and quantify AGN feedback in the JWST era.

astro-ph.GA↗

arXiv2026

Kinematic detection of dusty outflows from active galactic nuclei: Polycyclic aromatic hydrocarbon kinematics of type 2 quasars with JWST/MIRI spectroscopy

Active galactic nuclei (AGN) are thought to have dusty outflows, but unlike in the gas phase, it is challenging to measure the kinematics of dust. We present the detection and analysis of the kinematics of dust in five type 2 quasars at $z\sim0.1$ from the Quasar Feedback (QSOFEED) sample observed with JWST/MIRI spectroscopy. We used principal component analysis tomography to produce velocity maps of polycyclic aromatic hydrocarbon (PAH) features, which are the smallest carbonaceous dust particles. We were then able to compare velocity maps of the PAHs with emission lines of ionised and molecular gas. We produced velocity maps of the 11.3 $μ$m PAH feature, which traces large and neutral PAHs, for three out of the five objects, where all three show an outflow in the PAH kinematics. This becomes particularly clear after we subtracted disk kinematics, where the H$_2$ rotational transitions also show residuals consistent with an outflow. Compared to previous work with Seyfert galaxies, this work suggests that dusty outflows are more common at higher Eddington ratios, $λ_{\rm Edd}\gtrsim0.1$, in agreement with previous suggestions, although the sample size is small. We were unable to produce velocity maps for the 6.2 $μ$m PAH, which traces ionised PAHs, potentially due to differences in the intrinsic profile and/or suppression of the feature in AGN, which was seen previously in Seyfert galaxies. This reflects studies of PAH band ratios where AGN outflows have more neutral PAHs. This work demonstrates that dusty outflows may be common, particularly at high Eddington ratios, and it therefore plays a key role in the evolution and life cycle of AGN.

astro-ph.GA↗

arXiv2026

The Line Emission Terahertz Observatory (LETO): Exploring the lifecycle of the ISM and the origins of water

The Interstellar Medium (ISM) is the reservoir of baryonic matter from which stars and planetary systems are formed. It is also the repository of the material that is expelled at the end of the stellar evolutionary cycle feeding the baryonic matter reservoir. These evolutionary phases in the ISM together form a complex interplay driving planet and star formation and thus the evolution of our own Milky Way as well as galaxies at low and high redshifts. The design of the Line Emission Terahertz Observatory (LETO) has been optimized to investigate the impact of the ISM on star formation on galactic and extragalactic scales, study the processes that transform gas clouds into stars and planetary systems, and trace the flow of water in the ISM. To achieve these goals, LETO will carry out deep velocity-resolved wide-area spectroscopic observations of key FIR lines in the ISM covering an area of approximately 900 square degrees of the Galactic Plane. To complement our local view LETO will map a large sample of about 200 nearby galaxies in addition to surveys of Galaxies at Cosmic Noon. To shed light on the planet formation process, LETO will study the physical and chemical properties (especially gas mass) of numerous proto-planetary disks and stellar cores through pointed observations of the HD and H2O lines. LETO is a powerful FIR mission building on rich European heritage. To satisfy the requirements for sensitivity, resolving power and mapping speed, LETO utilizes a 3.5m class mirror and several bands with sensitive state-of-the-art multi-pixel heterodyne arrays. The bands together will cover the wavelength range from 56 to 666 micron and with the heterodyne receivers and backends high resolving power spectroscopy a set of key FIR atomic, ionic, and molecular lines can be studied in great detail. The mission is one of several selected for further study in the context of the ESA M8 call.

astro-ph.IM↗

arXiv2026

Investigating black hole accretion and feedback self-regulation in Seyfert galaxies using the FIRE-3 cosmological hydrodynamic simulations

Recent observations of local Seyfert galaxies show an intriguing connection between Active Galactic Nuclei (AGN) luminosity and a deficit of molecular gas on ~50pc scales compared to 200pc, the plausible imprint of AGN feedback. Motivated by these findings, we investigate the interplay between supermassive black hole (BH) accretion, AGN feedback, and nuclear gas reservoirs using high-resolution cosmological hydrodynamic simulations implementing FIRE-3 multi-phase interstellar medium (ISM) physics and multi-component BH accretion and feedback models. Focusing on the late-time evolution of four Milky Way-mass galaxies, we find recurrent cycles of increased gas inflow toward the accretion disc, enhanced BH accretion, feedback self-regulation, and suppressed gas inflow rate until the next fueling event. AGN winds interact with the ISM and escape preferentially through low-density polar channels after opening central cavities on ~10-500pc scales, regulating BH growth and producing episodic behaviour on ~10-100Myr timescales. The simulations reproduce the observed diversity of nuclear morphologies, gas concentrations, and AGN luminosities in late-type Seyfert galaxies, but do not exhibit a clear anti-correlation between gas concentration and AGN luminosity. Higher-luminosity AGN ($L_X$~$10^{41.5-43}$ erg s$^{-1}$) powered by the accretion disc reservoir can coexist with feedback-driven cavities, consistent with observations, but they are more common in simulated galaxies with centrally-peaked gas distributions. Although differences in sample selection, tracer choice, spatial resolution, and stochasticity in AGN fueling may impact underlying concentration-luminosity trends, the apparent tension between simulations and observations points to the timing between gas inflow, accretion-disc depletion, and feedback-driven clearing on ~50-200pc scales as a key constraint on AGN self-regulation models.

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arXiv2026

GATOS XIV: The first direct kinematic evidence of dusty outflows from AGN via PAH kinematics of local Seyfert galaxies with JWST

We present the first spatially resolved kinematic evidence for dust in the outflows of Active Galactic Nuclei (AGN). We utilise observations from JWST with NIRSpec IFU and MIRI MRS data of 10 local Seyferts and use Principal Component Analysis (PCA) tomography to extract the kinematics of Polycyclic Aromatic Hydrocarbon (PAH) features. PAHs comprise the smallest carbonaceous dust molecules in the Interstellar Medium (ISM), and produce emission features in the infrared providing the potential to measure kinematics. This is however challenging due to their broad shapes and variations in their intrinsic profile, prompting the need for techniques such as PCA tomography. We find that the velocity of the PAHs is similar to the molecular gas as traced by the rotational transitions of H$_2$, where for NGC 5728 and NGC 7582, both disk and outflow are present. We detect the outflow in the kinematics of large and neutral PAHs, namely the 11.3 $μ$m and 17 $μ$m PAH features, where after subtracting the disk, the velocity field matches that of high-ionisation potential lines such as [NeVI] (7.65 $μ$m, IP = 158 eV). Finally, we fail to detect kinematics of the 6.2 $μ$m PAH due to an altered intrinsic profile while the the 3.3 $μ$m PAH kinematics purely trace the circumnuclear disk. This suggests the PAHs in the outflow are more neutral and larger than in star-forming regions, consistent with PAH band ratios in previous studies of AGN.

astro-ph.GA↗

arXiv2026

Decoupling the AGN outflow and star-forming disk kinematics in the nuclear region of NGC 7582 with JWST NIRSpec and MIRI/MRS

We present a detailed study of the inner regions of NGC~7582, a nearby Seyfert~2 galaxy, from the Galaxy Activity, Torus and Outflow Survey (GATOS). The galaxy hosts a circumnuclear star-forming disk and an AGN-driven biconical ionised outflow. Using JWST NIRSpec and MIRI/MRS integral-field spectroscopy, we analyse ionic emission lines spanning a wide range of ionisation potentials (IPs, $\sim 8$--$126$ eV). Gaussian line-profile fitting reveals kinematic stratification: low-IP species ($\lesssim 20$ eV; e.g., [Fe II], [Ar II], [Ne II]) trace ordered disk rotation with PA $\sim -12 \pm 3^\circ$, while high-IP species ($\gtrsim 35$ eV; e.g., [O IV], [Mg IV], [Ne V]) follow the outflow with PA $\sim 54 \pm 10^\circ$. Outflowing gas exhibits systematically higher velocity dispersions ($119 \pm 13$ km/s) than the disk ($78 \pm 11$ km/s), consistent with turbulent or bulk motions. Intermediate-IP lines, [S III], [Ar III], and [Ne III], show contributions from both components, with the outflow characterised by higher dispersion, lower amplitude, and higher velocities in double-Gaussian fits. For these lines, a thin inclined disk plus one-dimensional outflow model enables robust separation and quantification of the disk and outflow velocity fields. The outflow is consistent with a hollow bicone capable of accelerating gas beyond the local escape velocity, implying most material is unlikely to be re-accreted. The ionisation cone opening angle shows no dependence on IP, indicating the AGN torus polar regions are largely unobscured. Our study provides new insights into AGN-driven outflows and circumnuclear disk dynamics, offering a framework to disentangle overlapping ISM kinematics in nearby active galaxies.

astro-ph.GA↗

arXiv2026

JWST reveals the diversity of nuclear obscuring dust in nearby AGN: nuclear isolation of MIRI/MRS datacubes and continuum spectral fitting

We investigate the capabilities of the mid-infrared instrument (MIRI) of James Webb Space Telescope (JWST) to advance our knowledge of AGN dust using the spectral fitting technique on an AGN collection of 21 nearby (z<0.05) AGN (7 type-1 and 14 type-2) observations obtained with the medium resolution spectroscopy (MRS) mode. This collection includes publicly available AGN and data from the collaboration of Galactic Activity, Torus, and Outflow Survey (GATOS). We developed a tool named MRSPSFisol that decomposes MRS cubes into point-like and extended contributions. We found statistically good fits for 12 targets with current AGN dust models. The model that provides good fits (chi2/dof<2) for {these 12 targets} assumes a combination of clumpy and smooth distribution of dust in a flare-disk geometry where the dust grain size is a free parameter. Still, two and one AGN statistically prefer the disk+wind and the classical clumpy torus model, respectively. However, the currently available models fail to reproduce 40% of the targets, likely due to the extreme silicate features not well reproduced by the models and signatures of water-ice and aliphatic hydrocarbon absorption features in most targets. New models exploring, for instance, new chemistry, are needed to explain the complexity of AGN dust continuum emission observed by JWST.

astro-ph.GA↗

arXiv2026

The CON-quasar stage of IRAS 07251-0248 E

ALMA continuum measurements of the local ULIRG IRAS 07251-0248 E at 667$μ$m reveal an extremely compact (R < 27 pc) and bright ($T_B$ >200 K) nucleus with an absorbing foreground envelope and a surrounding (R ~ 75 pc) disk or torus seen nearly face-on. The bright and unresolved nuclear emission implies large optical depths ($τ_{667μm}$ >0.5, corresponding to $N_H > 10^{25}$ cm^-2) of hot dust at >500 K. In addition, JWST observations of the source show strong mid-infrared (mid-IR) absorption in the ro-vibrational bands of H2O nu_2=1-0 (5-7 $μ$m) and of other species including CO, HCN, C2H2, CH4, and CO2, and Herschel/PACS observations exhibit strong and saturated absorption due to OH, H2O, CH^+, and CH. We propose a model in which the unresolved ALMA submillimeter and JWST mid-IR continua trace the same nuclear source, the former penetrating deep into the nucleus and the latter probing the nuclear photosphere. The continuum model, which includes trapping of photons (the "greenhouse" effect), indicates that the nuclear ($R_h$ ~ 13 pc) luminosity and luminosity surface density are ~10$^{12}$ Lsun and $Σ_{bol}$~ 5e8 Lsun pc^-2, arising from an active galactic nucleus (AGN) so buried that high-ionization lines are completely obscured. The observed mid-IR gas-phase molecular bands probe outflowing gas with velocities of ~160 km s^-1 and are reproduced with the predicted $T_{dust}$ profile, while the far-IR molecular absorption lines are generated in the surrounding thick disk or torus with $τ_{100 μm}$~10. We conclude that IRAS 07251-0248 harbors a compact obscured nucleus (CON) that hides an AGN currently emitting at quasar luminosity. While the observed outflow could be driven by radiation pressure, we favor the scenario of a (partially) energy-conserving hot bubble caught in a very early phase of the expulsion of the highly concentrated gas at the galactic nucleus.

astro-ph.GA↗

arXiv2026

Extending the Frontier of Spatially-Resolved Supermassive Black Hole Mass Measurements to at $1\lesssim z\lesssim2$: Simulations with ELT/MICADO High-Resolution Mass Models and HARMONI Integral-Field Stellar Kinematics

Current spatially resolved kinematic measurements of supermassive black hole (SMBH) masses are largely confined to the local Universe (distances $\lesssim100$ Mpc). We investigate the potential of the Extremely Large Telescope's (ELT) first-light instruments, MICADO and HARMONI, to extend these dynamical measurements to galaxies at redshift $1\lesssim z\lesssim2$. We select a sample of five bright, massive, quiescent galaxies at these redshifts, adopting their Sérsic profiles from HST photometry as their intrinsic surface brightness distributions. Based on these intrinsic models, we generate mock MICADO images using SimCADO and mock HARMONI integral-field spectroscopic data cubes using HSIM. The HARMONI simulations utilize input stellar kinematics derived from Jeans Anisotropic Models (JAM). We then process these mock observations: the simulated MICADO images are fitted with Multi-Gaussian Expansion to derive stellar mass models, and stellar kinematics are extracted from mock HARMONI cubes with pPXF. Finally, these derived stellar mass models and kinematics are used to constrain JAM dynamical models within a Bayesian framework. Our analysis demonstrates that SMBH masses can be recovered with an accuracy of $\sim$10%. We find that MICADO can provide detailed stellar mass models with $\sim$1 hour of on-source exposure. HARMONI requires longer minimum integrations for reliable stellar kinematic measurements of SMBHs. The required on-source time scales with apparent brightness, ranging from 5-7.5 hours for galaxies at $z\approx1$ (F814W, 20-20.5 mag) to 5 hours for galaxies at $1<z\lesssim2$ (F160W, 20.8 mag). These findings highlight the ELT's capability to push the frontier of SMBH mass measurements to $z\approx2$, enabling crucial tests of SMBH-galaxy co-evolution at the top end of the galaxy mass function.

astro-ph.GA↗

arXiv2026

JWST Discovery of High-Velocity Mid-Infrared Ionized Outflows in Ultraluminous Infrared Galaxies F11119+3257 and F05189-2524

Ultra-fast outflows (UFOs) are thought to be a driving mechanism of large-scale winds driven by active galactic nuclei, which cause significant galactic feedback through quenching star formation and regulating supermassive black hole growth. We present James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of two nearby ultraluminous infrared galaxies (ULIRGs), F11119+3257 and F05189-2524, with nuclear X-ray detected UFOs and kiloparsec-scale outflow. These galaxies show remarkably similar mid-infrared continuum and emission line features, notably including a high-velocity $v_{90}$ $\sim$ 4000 km s$^{-1}$ outflow detected in highly ionized neon emission lines, e.g., \nevi. In F05189-2524, we see a slightly slower biconical outflow extending up to $\sim2$ kpc in the same neon emission lines. Both sources show evidence of AGN-driven radiative feedback through a deficit of rotational molecular hydrogen lines in the nuclear region, $<$1 kpc from the central quasar, but no clear evidence of any molecular gas entrained in the quasar-driven outflow. Energetic analysis shows that the warm ionized gas in both of these sources contributes minimally ($\sim0.1-5\%$) to the momentum outflow rate of these sources and leaves the conclusions of previous literature unchanged: the energetics of these sources are broadly consistent with a momentum-conserving outflow.

astro-ph.GA↗

arXiv2026

The Supermassive Black Hole in the Nearby Spiral Galaxy M81: A Robust Mass from JWST/NIRSpec Stellar Dynamics

Despite its proximity, the mass of the supermassive black hole (SMBH) in the spiral galaxy M81 (NGC~3031) has remained uncertain, with previous dynamical measurements being unreliable. We present the first robust stellar-dynamical measurement of its mass using high-resolution, two-dimensional kinematics from JWST/NIRSpec observations of the central $3''\times3''$. By tracing stellar motions in the near-infrared, our data penetrate the obscuring nuclear dust and allow for the separation of stellar light from the non-thermal AGN continuum. We modeled the kinematics using JAM within a Bayesian framework, exploring a comprehensive suite of models that systematically account for uncertainties in the point-spread function, orbital anisotropy, and stellar mass-to-light ratio. This ensemble modeling approach demonstrates that a central dark mass unambiguously drives the central rise in velocity dispersion. The models yield a robust SMBH mass of $M_{\rm BH} = (4.78^{+0.07}_{-0.10})\times10^7$ M$_\odot$. This result resolves a long-standing uncertainty in the mass of M81's black hole and provides a crucial, reliable anchor point for SMBH-galaxy scaling relations.

astro-ph.GA↗

arXiv2026

Measuring the Central Dark Mass in NGC 4258 with JWST/NIRSpec Stellar Kinematics

We present a new stellar dynamical measurement of the supermassive black hole (SMBH) mass in the nearby spiral galaxy NGC 4258, a critical benchmark for extragalactic mass measurements. We use archival JWST/NIRSpec IFU data (G235H/F170LP grating) to extract high-resolution two-dimensional stellar kinematics from the CO bandhead absorption features within the central $3'' \times 3''$. We extract the stellar kinematics after correcting for instrumental artifacts and separating the stellar light from the non-thermal AGN continuum. We employ Jeans Anisotropic Models (JAM) to fit the observed kinematics, exploring a grid of 12 models to systematically test the impact of different assumptions for the point-spread function, stellar mass-to-light ratio ($M/L$) profile, and orbital anisotropy. All 12 models provide broadly acceptable fits, albeit with minor differences. The ensemble median and 68% (1$σ$) bootstrap confidence intervals of our 12 models yield a black hole mass of $M_{\rm BH} = (4.08^{+0.19}_{-0.33}) \times 10^7$ M$_\odot$. This paper showcases the utility of using the full model ensemble to robustly account for systematic uncertainties, rather than relying on formal errors from a single preferred model, as has been common practice. Our result is just 5% larger than, and consistent with, the benchmark SMBH mass derived from water maser dynamics, validating the use of NIRSpec stellar kinematics for robust SMBH mass determination. Our analysis demonstrates JWST's capability to resolve the SMBH's sphere of influence and deliver precise dynamical masses, even in the presence of significant AGN continuum emission.

astro-ph.GA↗

arXiv2026

Evidence of Feedback Effects in Low-luminosity Active Galactic Nuclei Revealed by JWST Spectroscopy

This letter presents an analysis of the infrared ($\sim 3-28\,μm$) spectra extracted from the nuclear ($r < 150$ pc) regions of four low-luminosity active galactic nuclei (AGN), observed by JWST NIRSpec/IFU and MIRI/MRS as an extension of the Galaxy Activity, Torus, and Outflow Survey (GATOS). We find that, compared to higher-luminosity AGN, these low-luminosity AGN exhibit distinct properties in their emission of ionized gas, polycyclic aromatic hydrocarbons (PAHs), and molecular hydrogen (H$_2$). Specifically, the low-luminosity AGN exhibit relatively weak high-ionization potential lines (e.g., [Ne V] and [O IV]), and the line ratios suggest that fast radiative shocks (with $v_{\rm s}$ of $\sim \rm 100s\,km\,s^{-1}$) are the primary excitation source of ionized gas therein. Under the low-excitation conditions of their nuclear regions, these low-luminosity AGN generally exhibit a higher fraction of PAHs with large size ($N_{\rm C} \gtrsim 200$), reflecting the preferential destruction of smaller PAH molecules by AGN feedback. Furthermore, the H$_2$ transitions in these low-luminosity AGN are not fully thermalized, with slow, plausibly jet-driven molecular shocks (with $v_{\rm s} \leq \rm 10\,km\,s^{-1}$) likely being the extra excitation source. Taken together with results from the literature, these findings indicate that feedback operates in both low- and high-luminosity AGN, albeit its impact varies with AGN luminosity. In particular, systematic variations in PAH band ratios are found across AGN, demonstrating the differing influence of feedback in AGN of varying luminosities and highlighting the potential of PAH band ratios as diagnostics for distinguishing kinetic- and radiative-mode AGN feedback.

astro-ph.GA↗

arXiv2026

GATOS XI : Excess dust heating in the Narrow Line Regions of nearby AGN revealed with JWST/MIRI

We present JWST/MIRI imaging of eight nearby Active Galactic Nuclei (AGN) from the GATOS survey to investigate the physical conditions of extended dust in their narrow line regions (NLRs). In four galaxies (ESO 428-G14, NGC 4388, NGC 3081, and NGC 5728), we detect spatially resolved dust structures extending ~100-200 pc along the NLR. In these systems, we find a strong link between the morphology of the dust, the radio ejecta, and the coronal [Si VI] emission, implying that dust carries imprints of the processes shaping the NLR. Using spatially resolved spectral energy distributions, we show that dust in the NLR has systematically steeper slopes than star forming clumps. This dust emits at temperatures in the range 150 - 220 K, at a distance of ~150 pc from the nucleus. Using simple models, we show that, even under optimistic assumptions of grain size and AGN luminosity, the excess MIR emission cannot be explained by AGN illumination alone. We interpret this excess heating as in-situ. We show that shocks with velocities of $v_{\rm shock} \sim 200- 400 \, \rm km/s$ in dense gas can close this gap, and in some cases even account for the total observed emission. This, combined with multiple lines of evidence for shocks in these regions, supports a scenario in which shocks not only coexist with dust but may be playing a key role in heating it. Our findings reveal shocks may be an important and previously overlooked driver of extended dust emission in the central hundreds of parsecs in AGN.

astro-ph.GA↗

arXiv2025

RIOJA. A Clumpy Galaxy Assembly at Redshift 6.81 Revealed by JWST

Spatially resolved multi-wavelength analysis is essential to study galaxy formation and evolution. A UV-bright galaxy COS-2987030247 at $z = 6.81$ is one of the Rosetta Stones in the epoch of reionization for which JWST NIRSpec Integral Field Spectroscopy, NIRCam imaging, and ALMA data are available thanks to the RIOJA program. We identified the rest-frame optical emission lines from the ionized hydrogen, oxygen, and neon gas. The \OIII\,5008Å line emission and the NIRCam images show a complex kinematical and morphological structure where two bright main and three faint clumps are identified in a 10 kpc extent. The system is not classified as a purely rotation-dominated disk. The multiple clumps are instead consistent with a merger-related origin, including either distinct galaxies in interaction or star-forming clumps formed through tidal gas compression during a merger. The spatially resolved emission line fluxes show that dust attenuation, metal enrichment, and ionization parameter are preferentially enhanced in the star formation peaks. Our SED fitting suggests that the main clumps are in a moderately dust-attenuated star forming phase ($A_{\rm V} = 0.2$--$0.3$ and SFR(H$α$) $\sim 10$\,M$_\odot$\,yr$^{-1}$) with almost zero escape fraction of ionizing photons. In contrast, the sub-clumps are dust-free and lying on or below the main sequence of star-forming galaxies. These sub-clumps may work as a perturber that triggers the clumpy starburst in the surrounding gas through the merger event.

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