Illuminating the Active Universe: Multi-Wavelength and Multi-Messenger Insights into AGN

14 Sept 2026, 13:00 → 17 Sept 2026, 14:40 Europe/Amsterdam

Auditorium Eridanus (ESO)

Elisa Resconi (Technical University Munich), Narek Sahakyan (ICRANET-Armenia IO), Paolo Giommi

Poster.jpeg

Monday 14 September

Welcome

Blazars

1 Old and very recent results on blazars

In this presentation, I will briefly review my research on blazars, much of which was carried out in collaboration with Paolo Padovani.
I will then present very recent results on the cosmological properties of blazars based on the largest complete and statistically well-defined sample of X-ray-selected blazars derived from the eRASS1 survey. I will also discuss recent identifications of blazars associated with Fermi-LAT gamma-ray sources from the FL16Y catalog and with IceCube high-energy neutrino events.

Speaker: paolo giommi (INAF-Brera Observatory, Milan)

2 Blazars: what have we learned ? What now ?

In the past two decades tremendous progress has been made in the observation of jetted AGNs, thanks to a new generation of instruments, especially in X-rays and gamma-rays.
From population studies (going lower in luminosity, further in redshift, broader in SEDs and source types) to new phenomenology (ultra-fast variability, hard TeV spectra, changing-look AGNs, neutrinos association, X-ray polarization properties), we have now a much better grasp of the blazar phenomenon and jet properties, but still not a clear answer to most of the fundamental questions, such as: how and why some AGNs launch relativistic jets, what is the main particle acceleration and emission mechanism in the jet, where the emission comes from and even which type of particles produce the observed gamma-ray emission.
In this contribution I revisit some old and new issues in the context of the latest results, and discuss some perspectives for the next steps.

Speaker: Luigi Costamante (Independent researcher)

3 AGN observations in the gamma-ray band

Active Galactic Nuclei (AGN) serve as some of the universe's most powerful and extreme cosmic accelerators. Over the past several decades, our understanding of these objects has evolved from early taxonomic classifications into a coherent framework driven by broad multi-wavelength surveys. Today, the advent of next-generation instrumentation for high-energy photon and neutrino astronomy is pushing this paradigm into a new era. In this talk, I will present recent highlights from AGN observations in the gamma-ray band, drawing from current space-borne and ground-based facilities like Fermi-LAT and MAGIC, H.E.S.S. and VERITAS, while looking forward to the transformative capabilities of the Cherenkov Telescope Array Observatory (CTAO). I will particularly report on some insights gained from extensive, multi-decade, multi-instrument monitoring campaigns of a select group of bright, nearby blazars. These coordinated observations reveal a staggering complexity in the temporal evolution of broadband emission and expose distinct flavors of flaring activity across different epochs. Ultimately, these long-term datasets underscore the absolute necessity of continuous, multi-wavelength, and multi-messenger monitoring to fully decode the intrinsic particle acceleration mechanisms and dynamic environments of jetted AGN.

Speaker: Dr David Paneque

4 Redshift Determination of gamma-ray blazars for the Cherenkov Telescope Array Observatory

Blazars represent the most numerous class of High Energy (HE; E about 50 MeV to few 100 GeV) and Very High Energy (VHE; E about 100 GeV to 10 TeV) gamma-ray emitters.

The knowledge of their redshift is fundamental for understanding their emission and conducting population studies. Furthermore, the redshift is essential for indirect studies of the extragalactic background light as well as for searches regarding Lorentz invariance violation and axion-like particles. BL Lacs are a particular type of blazars characterized by their nearly featureless, continuum-dominated optical spectra, which pose a challenge to the measurement of their corresponding redshift. As a result, this important quantity is available for only about half of the currently known gamma-ray BL Lacs.

The upcoming Cherenkov Telescope Array Observatory (CTAO), a ground-based gamma-ray observatory with one site in La Palma in the Canary Islands and one planned for construction in Paranal, Chile, will detect several hundred VHE gamma-ray blazars in the near future. In preparation for CTAO operations, we initiated a program several years ago to measure redshifts for gamma-ray blazars likely to be detected by the CTAO. Following initial Monte Carlo simulations to select a suitable sample, we organized optical observing campaigns involving mainly spectroscopic observations to efficiently constrain their redshifts. This extensive, long-term program has resulted in six refereed publications, 54 new redshift and 11 redshift lower limit measurements.

In this talk we will describe our campaigns, highlight the main results achieved, and outline planned future developments.

Speaker: Dr Paolo GOLDONI (APC/IRFU)

15:00 Coffee break

Blazar Variability

5 Multiwavelength Odyssey of 3C 279 and Long-Term Monitoring of Gamma-Ray-Loud AGNs with the Nanshan 26 m Radio Telescope

We present results from our comprehensive multiwavelength studies of the FSRQ 3C 279 (Krishna Mohana A et al. 2024, MNRAS, 527, 6970; 2025, ApJ, 989, 125) — one of the brightest and most variable blazars in the gamma-ray sky — alongside the first data release of the quasi-Simultaneous Multiwavelength Monitoring of gamma-ray-loud AGNs with the Nanshan 26 m radio telescope (SMMAN; Cui, Krishna Mohana A et al. 2026, ApJS, 283, 69). We carried out a multiband radio cross-correlation analysis of 3C 279 spanning over a decade (2008–2022) across seven frequency bands ranging from 2 to 230 GHz. Prominent flares appear first at higher frequencies and propagate to lower frequencies, with lag–frequency relations well described by linear fits of slope $\sim -30$ day GHz$^{-1}$. By comparing these variations with the evolution of bright moving knots in multi-epoch VLBA maps, we infer physical changes in the jet, with some variations consistent with shock propagation and others better explained by a change in the Doppler beaming factor as the knot trajectory bends slightly, given a small viewing angle to the jet. Extending this to a full broadband perspective, we model 168 quasi-simultaneous SEDs constructed from Fermi-LAT, Swift-XRT/UVOT, WEBT, and radio data over the $\sim14$-year Fermi era. A one-zone leptonic scenario, with the emission region outside the broad-line region, successfully reproduces the observed emission, revealing that flares are driven by increases in the Doppler beaming factor coupled with variations in the emitting electron population. The SMMAN program has monitored 131 northern gamma-ray-loud AGN at 4.8 and 23.6 GHz over eight years (2016-2024) with the Nanshan 26 m Telescope. Sources show stronger variability at 23.6 GHz, with BL Lacs more variable than FSRQs. FSRQs are more radio-luminous, and both classes exhibit higher gamma-ray loudness than radio galaxies. The SMMAN dataset, incorporated with other historical and ongoing monitoring programs, will provide a unique opportunity to investigate the evolution of SEDs, search for QPOs, and analyse supermassive black hole binary systems.

Speaker: KRISHNA MOHANA AMMENADKA (Xinjiang Astronomical Observatory (XAO), Chinese Academy of Sciences (CAS), China)

6 Probing Relativistic Jets Through Multiwavelength Observations of Blazars

Blazars represent the most extreme subclass of active galactic nuclei, characterized by relativistic jets aligned close to the line of sight and exhibiting strong variability across the electromagnetic spectrum. Their non-thermal emission is dominated by relativistically beamed radiation from the jet, making them ideal laboratories for studying particle acceleration and energy dissipation under extreme physical conditions. X-ray observations provide a powerful probe of the particle acceleration and radiative processes operating within these jets. We present the first detailed spectral and timing study of the TeV blazar Mrk 421 based on archival observations from the NICER mission.
The source exhibits pronounced X-ray variability on both intraday and long-term timescales. Spectral modeling using power-law, broken power-law, and log-parabolic functions indicates that the log-parabolic model provides the best description of the X-ray spectra. Hardness ratio analysis reveals a clear harder-when-brighter behavior, implying enhanced particle acceleration during high-flux states. We also find significant correlations among the spectral parameters, including a positive relation between the spectral index ($\alpha$) and curvature parameter ($\beta$), as well as an anticorrelation between the synchrotron peak energy ($E_{\rm p}$) and spectral curvature.

Using a log-parabolic electron energy distribution within a synchrotron jet framework, we reproduce the observed anticorrelation between $E_{\rm p}$ and $\beta$, consistent with energy-dependent particle acceleration processes in turbulent relativistic jets. The observed spectral evolution, together with the rapid variability, suggests that the X-ray emission originates from a compact region within the jet where particle acceleration and radiative cooling compete on short timescales. These results provide new insights into the physical mechanisms governing the high-energy emission of blazars and demonstrate the capability of NICER observations to constrain particle acceleration processes in relativistic jets.

Speaker: SANGEETHA KIZHAKKEKALAM (Janusz Gil Institute of Astronomy, University of Zielona Gora, Poland)

7 Full-Stokes monitoring of blazars at mm and cm wavelengths

Blazars, the subclass of jetted AGN with their outflow axes closely aligned to our line of sight, comprise one of the most energetic, long-lived phenomena in the Universe. They are among the main constituents of the high-energy sky, especially in gamma-rays and up to TeV energies, and one of possible sources of astrophysical neutrinos. The low-energy part of their SEDs is understood as incoherent synchrotron emission from their jets, which spans from radio to optical, UV or even X-rays and is both linearly and circularly polarized. On top of their persistent broadband emission, blazar jets often show pronounced variability across the electromagnetic spectrum with timescales from days/months down to minutes.

In this presentation, we will demonstrate our efforts to capture the complex phenomenology of blazar jets through dedicated multi-wavelength polarization monitoring programs using several large radio facilities operating at mm and cm wavelengths, such as POLAMI, SMAPOL, BEAM-ME and QUIVER. Our observations, which cover two decades of frequency (2.6 GHz — 230 GHz), are used to follow the flux density and polarization variations of our blazar sample with a ~3-week cadence. The linear and circular polarization parameters and their variability are used to constrain the jet physical conditions, such as the magnetic field strength and topology, the plasma composition and energetics, and study their dynamics. In addition, we respond to selected neutrino alerts and coordinate with multi-wavelength campaigns, including IXPE or MAGIC, to identify the high-energy emission mechanism of blazar jets based on the expected multi-band polarization characteristics.

Speaker: Ioannis Myserlis (Institut de Radioastronomie Milimétrique (IRAM))

8 Color-like Gamma-ray Spectral Variability in Blazar Flares

Blazars are highly variable gamma-ray sources whose flaring activity provides a direct probe of particle acceleration and radiation processes in relativistic jets. However, the gamma-ray spectral behavior associated with individual flare peaks has not yet been characterized systematically for a large blazar sample. In this work, we investigate whether blazars become spectrally harder or softer during gamma-ray flares by combining long-term Fermi-LAT light curves with source information from the 4LAC catalog.

We identify active gamma-ray states and flare peaks from the Fermi-LAT light curves, and measure the photon-index behavior around each peak. The photon index at the flare peak is compared with the characteristic photon index of the same source, allowing us to evaluate spectral hardening or softening on a source-by-source basis. We also examine daily shifted time windows around the peak to explore whether the spectral change is confined to the flare peak or extends to neighboring time bins.

Applying this framework to a large blazar sample, we identify more than one thousand gamma-ray flare peaks, several hundred of which have sufficient photon-index coverage for statistical analysis. We find that spectral changes during flares are common, with spectral hardening appearing frequently at flare peaks. At the source level, blazars can be separated into several groups according to their flare-related spectral behavior, including hardening-dominated, softening-dominated, mixed, and non-significant cases.

These results suggest that gamma-ray flares in blazars are often accompanied by measurable changes in the particle-energy distribution or emission conditions. The diversity of spectral behavior among sources indicates that flare-related spectral variability is not governed by a single universal mechanism, but may depend on source class, jet environment, and flare properties.

Speaker: TIANFANG ZHANG (NAOJ)

9 Multi-band optical variability of OJ 287 during 2015-2025

We present multi-band optical observations of OJ 287 from 2015 to 2025 with a focus on its optical activity on diverse timescales. A total of 2296, 10927, 11484, and 2982 data points are obtained in B, V, R, and I bands, respectively. The densely sampled observations allow us to keep track of the source evolution that it has exhibited since the start of the predicted major optical flaring activity at the end of 2015. The study reveals clear and persistent bluer when brighter trends in both the long-term and short-term variations. Different bands were cross-correlated with discrete correlation functions, which peak at zero lag, implying co-spatial emission. Using eight optical spectra in the low flux states of OJ 287 taken from 2017 October 21 to 2017 November 22, from Steward Observatory, we estimate the central black hole mass to be at least 3.9 × [9dex] M⊙ from the [O III] line width.

Speaker: Omar Kurtanidze (Abastumani Observatory)

10 Recollimation shocks and nonlinear dynamics in relativistic AGN jets

Relativistic jets from Active Galactic Nuclei are quintessential multi-messenger engines, yet a persistent challenge remains in connecting their macroscopic evolution to the localized kinetic scales responsible for high-energy emission. This work presents high-resolution 2D and 3D relativistic magnetohydrodynamic (RMHD) simulations using the PLUTO code to bridge this gap. We investigate the propagation of jets through stratified environments, focusing on how external pressure gradients and confinement drive the formation of complex recollimation shocks and turbulent flow patterns. Our results reveal that the non-linear development of these structures creates robust, time-variable sites of enhanced energy dissipation. By identifying these dissipation zones, we provide a physically motivated framework for interpreting the high-energy variability and evolving polarization signatures observed in blazars and radio galaxies. These simulations provide a theoretical link that translates global fluid dynamics into the discrete emission features observed.

Speaker: Stella Boula (INAF-OAB)

11 Particle energization in strongly magnetized mildly relativistic collisionless shocks

We demonstrate that magnetized mildly relativistic shocks may be efficient particle accelerators capable of accounting for the intense X-ray and gamma-ray emission observed in jets of active galactic nuclei (AGN).

We employ the particle-in-cell (PIC) method to investigate a mildly relativistic shock in a magnetized electron-ion plasma under two magnetic field configurations: an oblique shock with the magnetic field oriented just below the critical angle and a quasi-parallel shock. While the only difference between both simulations is the obliquity of the magnetic field, the results show notable difference between both configurations.

In the oblique configuration, a portion of electrons, which move predominantly along magnetic field lines, is efficiently trapped by the cross-shock potential. Trapped cannot readily escape and instead oscillate within the potential peak at the shock. During this motion, the motional electric field, aided by the ExB drift, accelerates trapped electrons to very high energies. Ions are likewise trapped, albeit within potential troughs, and attain comparable maximum kinetic energies to that of electrons. A portion of trapped ions may escape upstream, undergoing shock surfing acceleration along the shock front.

In the quasi-parallel configuration, elliptically polarized whistler waves are self-generated at the shock and propagate upstream. A fraction of ions escape from the non-stationary downstream region into the upstream, where they are trapped by longitudinal electric waves generated by the oblique propagation of whistler waves. This results in efficient heating to relativistic temperatures. Additionally, several plasma instabilities develop, including the modified two-stream instability (MTSI) and the parametric decay instability (PDI), further contributing to enhanced turbulence and heating.

Speaker: Gabriel Torralba Paz (Max Planck Institute for Plasma Physics)

Tuesday 15 September

X-Ray AGN

12 AGN in the X-ray band: recent results and implications for the big picture

Recent X-ray spectroscopic and polarimetric observations of nearby Seyfert galaxies are providing new constraints on the physics and geometry of the innermost AGN regions, where hot and dense plasmas are present and powerful outflows are launched. At the same time, in the distant Universe, new AGN populations discovered by JWST are escaping detection in the X-rays, even in the deepest X-ray fields observed to date, challenging our current view of accretion onto supermassive black holes.

In this talk, I will review these new X-ray results on AGN physics and demographics, and discuss how they may combine with AGN neutrino observations to advance our understanding of the 'big picture'.

Speaker: Roberto Gilli (INAF-OAS Bologna)

13 The AGN content in eROSITA/DR2

Galaxy evolution can only be understood if its AGN phases are accounted for. For that, a complete and pure census of AGN is needed. Hunting for AGN in X-rays is the most obvious way to go, given the low emission from galaxies at this frequency. In the last 20 years, XMM and Chandra have mostly provided us with pencil-beam surveys, thus sampling the faint, high-redshift regime. Finally, with eROSITA, we can also sample the rare (local and z>5.5) and faint Universe. In my talk, I will review the multi-wavelength properties (including redshifts) of the first eROSITA/DR2 AGN sample and compare them with AGN selected from other surveys.

Speaker: Mara Salvato

14 X-ray Polarization in Active Galactic Nuclei

X-ray polarimetry has opened a new window on the physics of active galactic nuclei, providing direct information on geometry, magnetic fields, scattering regions, and the particle acceleration and emission processes operating in relativistic jets that cannot be obtained from spectroscopy, timing, or imaging alone. In this talk, I will review the emerging observational picture from recent X-ray polarization measurements with the Imaging X-ray Polarimetry Explorer (IXPE), highlighting what they reveal about accretion flows, coronae, relativistic jets, and the connection between disk and jet emission. I will also discuss how X-ray polarimetry complements multi-wavelength and multi-messenger studies, and how future observations can help distinguish between competing physical scenarios for high-energy emission in active galaxies.

Speaker: Stefano Bianchi (Università degli Studi Roma Tre)

15 The Limitations of AGN Reverberation Mapping: Bayesian analysis shows as few as 5% of MgII Sources may Reverberate

Reverberation mapping (RM) of Active galactic nuclei is a multi-messenger time domain that provides one of the most direct probes of the geometry and kinematics of the AGN broad-line region. It combines broad-band photometry and emission line spectroscopy to construct light curves to measure time delays between the continuum and line variability, with this lag time acting as a ruler of the broad line region's characteristic scale. However, modern multi-year "industrial scale" RM surveys like OzDES and SDSS are impacted by the problem of "aliasing", wherein the multimodal lag posterior distribution confounds tools like JAVELIN into returning incorrect or entirely spurious false positive lags. In this work we use a new fully Bayesian lag fitting tool, LITMUS, to construct a new RM lag measurement framework that leverages LITMUS's Bayesian evidence measurements to identify false positive lag measurements in a principled way. Using our new pipeline to re-analyse the full OzDES reverberation mapping sample, we find that previous reverberation mapping studies are likely to have markedly overestimated the confidence of recovered lags, and that, while the H-beta and CIV emission lines reverberate in the full sample, the MgII line does not exhibit detectable reverberation in a large fraction of AGN.

Speaker: Hugh McDougall (The University of Queensland)

10:50 Coffee break

X-Ray AGN

16 Hard X-ray and Millimeter Broadband Study of AGN Corona

The X-ray emission in active galactic nuclei (AGN) is produced in a hot corona, where energetic electrons up-scatter UV/optical photons from the accretion disk into X-rays through inverse Compton scattering. Hard X-ray observations from NuSTAR provide key constraints on the coronal temperature and optical depth, while recent studies have revealed that millimeter (mm) synchrotron emission offers a powerful new probe of the corona’s size, magnetization, and particle distribution. We will present new constraints from NuSTAR and multi-band ALMA observations, showing how the synergy between mm and hard X-ray measurements is enabling a more complete and self-consistent picture of AGN coronae.

Speaker: Xiurui Zhao (Caltech)

17 X-ray spectral steepness in AGN: accretion rate is not the whole story

Steep X-ray spectra in active galactic nuclei (AGN) are widely interpreted as a signature of high accretion rates, a claim gaining renewed relevance in light of the JWST discoveries of X-ray-weak AGN at high redshift. Are these primeval objects accreting near or beyond the Eddington limit? To address this, we analyzed the X-ray emission of a large AGN sample from the latest Sloan Digital Sky Survey release. We find that the correlation between X-ray photon indices and accretion rate is surprisingly weak and strongly dependent on the choice of accretion rate proxy. We conclude that, while high accretion rates may contribute to spectral steepening, another physical driver must account for the observed spread in AGN photon indices.

Speaker: Andrea Sacchi

Radio AGN

18 Radio variability as probe of corona/jet-base origin in RQ AGN

The origin of radio emission in radio-quiet AGN remains a central debate regarding the nature of accretion and feedback around supermassive black holes. While this emission is often attributed to star formation or diffuse outflows, current evidence increasingly points toward a compact jet base or a magnetized corona tied to the sub-parsec accretion engine. The most definitive diagnostic for identifying these processes lies in comparing radio and X-ray flux variations, as correlated or lagged variability provides compelling evidence of a direct physical connection between the two components. In this talk, I present a systematic investigation of the radio variability properties of radio-quiet AGN, a territory that remains largely unexplored. These sources exhibit a diverse range of amplitudes and timescales, and I examine how these properties scale with Eddington ratios and black hole masses. By comparing these results with X-ray light curves, I discuss how specific time lags may indicate a synchrotron jet nature similar to the behavior observed in X-ray binaries.

Speaker: FRANCESCA PANESSA (IAPS INAF)

19 The curious case of the FR0s jet morphology

The classical Fanaroff-Riley (FR) classification of radio galaxies is primarily based on powerful and extended FRI and FRII sources. However, more sensitive radio and optical surveys have revealed a large population of compact radio galaxies in the local Universe, known as FR0s, which outnumber FRIs by a factor of 5. Despite these populations share many properties, FRIs develop powerful kpc-scale relativistic jets while the FR0s less relativistic jets tend to stop at sub-kpc-scale and be more easily disrupted by the ISM. Current evidence suggests that black hole spin, magnetic field or specific jet composition play a role in causing these differences, while the role of the environment is still unclear. In this contribution, I will present a multi-frequency study of FR0 and FRI radio galaxies (RG), including data from SKA pathfinders and precursors, to investigate how apparently similar central engines can produce such diverse radio morphology across the RG populations.

Speaker: LEONARDO PENNA (University of Cagliari, INAF-OAC)

20 Resolved Radio Emission from a Radio-loud, Super-Eddington Quasar at z=3.4

AGN in the local universe exhibit an inverse correlation between radio-loudness and Eddington ratio. Furthermore, the radio emission in local radio-loud AGN is typically dominated by a large scale jet. I will present the results of a very long baseline interferometry study of eROSITA Final Equatorial Depth Survey J084222.9+001000, a super-Eddington ($\lambda_{\rm Edd, UV}$ = 1.4 and $\lambda_{\rm Edd,X-ray}$ = 12.8) quasar at z = 3.4 with a radio-loudness ratio of $R_{\rm obs}$ = 3.0. The radio morphology is composed of an unresolved core and a collimated jet extending $\gtrsim$ 745 pc. The jet has a relativistic speed of $v \gtrsim 0.19c$ and a viewing angle of $\phi \lesssim 79^\circ$ to the line of sight. The radio emission from the compact, flat-spectrum core dominates over that of the jet by over an order of magnitude. These properties differ significantly from low-z AGN, suggesting that this source maybe a member of a distinct, high-z AGN population which, in turn, has implications for AGN feedback and SMBH-galaxy co-evolution in the early universe.

Speaker: Ingyin Zaw (New York University Abu Dhabi)

13:10 Lunch

AGN Emission

21 Beyond One-Zone Models: Linking Multi-Wavelength Phenomenology to Acceleration Microphysics in Blazar Jets

The paradigmatic understanding of the physical processes operating in the relativistic jets of blazars, traditionally framed within one-zone models, has been challenged by recent observational evidence. IXPE multi-wavelength campaigns support multi-zone scenarios; delays between radio and gamma-ray flares point to jet acceleration and propagation effects; and short- and long-term inter-band variability reveal a complex interplay between particle acceleration and radiative cooling. These findings also indicate a strong connection between the dissipation site and the balance between cooling and acceleration channels.
Despite this substantial body of phenomenological evidence, theoretical interpretation and modeling still face major challenges, largely due to parameter degeneracies and the limited discriminatory power of current models. As a result, a clear understanding of the connection between micro- and macro-physical processes remains elusive. In this talk, I will discuss key phenomenological patterns emerging from recent observations and show how they can be used to develop modeling frameworks that connect microphysical acceleration processes with the large-scale jet phenomenology observed in blazars. Particular attention will be devoted to the acceleration process, comparing scenarios in which shocks act as the main sites of particle acceleration with alternatives based on hierarchical turbulence and magnetic reconnection, while emphasizing the ubiquitous role of a stochastic acceleration component.

Speaker: Dr Andrea Tramacere (Université de Genève)

22 Radiative models for rapid AGN flares

Rapid variability over a large range of wavelengths is a defining feature of blazars and radio galaxies. The shortest time scales are observed at the highest gamma-ray energies, with significant flux variations over a few days or hours not uncommon, while the most extreme events reach the minute time scale. The origin of the underlying processes is not well known, but most scenarios place the emission region inside the relativistic jets, where rapid flares can be caused by macroscopic effects or by transient particle acceleration and emission processes. Particle acceleration can occur in shocks or turbulences, but might also be due to magnetic reconnection, depending on the physical conditions of the emission region. Quite possibly there is more than a single process at play behind the variety of observed flare shapes and their different time scales.
I will provide a short overview of the main types of models trying to explain rapid flare emission in such sources, with a focus on their predictions of light-curve shapes, spectra and intrinsic time delays.

Speaker: Andreas Zech (Observatoire de Paris)

23 Multi-scale Outflows in M81: From Sub-parsec to Hundred-parsec Scales

Galactic circumnuclear regions, where stars and supermassive black holes interact with the interstellar medium, are crucial for understanding black hole feeding, feedback, and galaxy co-evolution. However, the connection between black hole feedback and the surrounding interstellar medium remains elusive. Using CAHA/PPAK and JWST observations, we investigate multi-scale outflows in the nearest low-luminosity active galactic nucleus (LLAGN), M81. Together with previously Chandra and Gemini/GMOS observations, we identify outflow signatures from sub-parsec to ~100-pc scales, providing a coherent view of the ionized gas kinematics and revealing a continuous feedback process. Our analysis offers new insights into how weak AGN regulate their immediate environments.

Speaker: Zongnan Li (Korea Astronomy and Space Science Institute)

24 The multiphase circumnuclear region of Centaurus A as seen with JWST/MIRI MRS observations

Supermassive black holes power Active Galactic Nuclei (AGN), injecting energy that regulates accretion and shapes host galaxies. We investigate the morphology, excitation, and kinematics of molecular hydrogen (H2) in the inner circumnuclear disk of Centaurus A, the nearest radio galaxy. We present JWST/MIRI MRS integral-field spectroscopy of the central 170x100 pc2 at 0.3"-0.7" (5-12 pc) resolution, focusing on pure rotational H2 lines. The spectra show strong nuclear continuum and bright H2 emission from S(1) to S(8), including the first S(8) detection in Centaurus A. Optically thin nuclear lines enable maps of temperature, column density, and ortho-to-para ratio from spaxel-level excitation-diagram fitting. Warm H2 shows a complex morphology, dominating the central region where CO emission is weak or undetected. Low-excitation H2 lines trace an inhomogeneous ring with a 20-pc-radius cavity aligned with the jet's near side, suggesting that the jet affects the morphology of the molecular disk. Higher-excitation lines form filamentary structures around the AGN. Kinematics are rotational with an S-shaped distortion, indicating non-circular motions or a warped disk. A coherent, low-dispersion (70 km/s) streamer spirals inward. A power-law temperature distribution yields a warm (100-2000 K) H2 mass of (5.6+/-1.4)e5 Msun and a dynamical mass of 5e8 Msun within 100 pc. Shock excitation is supported by enhanced H2/continuum and H2/PAH ratios, elevated [Ne III]/[Ne II], and sub-equilibrium ortho-to-para ratios (1.6-2.4). Turbulent dissipation can balance H2 cooling and likely dominates heating beyond 30 pc. In the inner 100 pc of Centaurus A, AGN feeding and feedback are linked: shocks excite H2, regulate the gas temperature, and prevent cooling below 100 K, explaining the weak CO emission and lack of a massive outflow. These shocks may drive angular momentum loss and help fuel the nucleus.

Speaker: Lorenzo Evangelista (Institut d'astrophysique de Paris)

16:50 Coffe break

AGN Emission

25 JWST/MIRI Observations of the Nuclear Region of NGC 7582

Obscured active galactic nuclei (AGN) represent a crucial phase of supermassive black hole growth, in which dense circumnuclear dust hides the central engine and reprocesses its radiation into the infrared. Earlier mid-infrared observations with the Spitzer Space Telescope provided key constraints on dusty torus models but lacked the sensitivity and spectral resolution required to reveal subtle ice absorption features in nearby AGN. Recent JWST/MIRI mid-infrared spectra of the central region of Seyfert 2 galaxy NGC 7582 have revealed prominent ice absorption feature. This is the first time we have detected the icy band at 6 μm in the local galaxies. Such an ice absorption band has not been included in existing AGN or starburst dust radiative transfer models. In particular, the template spectra from current AGN model libraries severely underestimate the mid-infrared flux when compared with the JWST data. To resolve this discrepancy, we propose a new class of frosty AGN models. These models incorporate icy grain mantles into clumpy dust torus configurations. Using Monte Carlo radiative transfer calculations of the spectral energy distribution, we account for both the imprint of embedded ice features and the additional heating contribution from Type-I quasar spectra, thereby extending and updating the AGN model library of Siebenmorgen et al. (2014). Our framework enables us to address several key questions: Under which physical conditions can water freeze onto dust grains in AGN environments? Is the ice reservoir primarily associated with the torus or with circumnuclear starburst regions? And more broadly, why do current AGN models fail to reproduce JWST/MIRI mid-infrared spectra? In this talk, we will present the physical conditions required to produce the 6 μm water-ice band in AGN, discuss the implications for the torus structure, and outline how the inclusion of icy dust fundamentally alters the interpretation of spectral energy distribution (SED) of AGN.

Speaker: Khushboo Khushboo (European Southern Observatory)

26 Bridging diagnostics: Multi-wavelength consistency and discrepancy in the classification of local AGN

Understanding the interplay between AGN and their host galaxies is central to modern galaxy evolution studies. As we move beyond isolated diagnostics toward a unified, multi-wavelength framework, understanding the reliability and limits of AGN classification methods becomes necessary for interpreting the feedback mechanisms that shape galaxies. We address this challenge by combining optical and X-ray AGN diagnostics: Specifically, the galaxy sample of the extended Calar-Alto Legacy Field spectroscopy Area (CALIFA) survey, an optical wide-field integral field unit survey of low redshift galaxies, and the Data Release 1 main source catalogue of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA), a sensitive wide-field X-ray telescope. This yields a sample size of 254 potential AGN hosts in the local Universe. We use BPT diagrams and the WHaD diagram, both nuclear activity diagnostics based on optical emission line information, and perform a survey cross-matching to derive an X-ray AGN classification. The AGNs for which multiple classifications agree are identified, followed by a detailed inspection of the mechanisms behind their agreement/disagreement. 40% of the X-ray AGNs are classified as active in at least one of the optical classifications. Not only does the disagreement between classifications underscore the limitations of single-diagnostic approaches and suggests a complex temporal and geometric picture of AGN activity, global properties determined in iEDGE reveal a bias in the galaxy populations depending on classification. This work demonstrates the power of multiwavelength studies in contributing to the broader goal of reconciling diverse observational signatures into a consistent picture of AGN activity and its impact. I will also show preliminary findings doing a similar comparison in KILOGAS, allowing to investigate resolved gas properties and their relation to AGN feedback for a sample of unprecedented size.

Speaker: Helene Kast

27 The prevalence of radio-excess AGN within the SCUBA-2 detected sample of sub-millimeter sources

Since their discovery, due to a very negative K-correction and strong constraints on the evolutionary models, galaxies detected in the sub-millimeter part of the spectrum have remained an important part of understanding galaxy evolution. Physically, they correspond to dusty star-forming galaxies. However, a number of them also host AGNs, as evidenced by a number of previous studies. In this work we estimate the prevalence of radio-excess AGNs within a SCUBA-2 detected sample of sub-millimeter sources, observed in the UDS and COSMOS fields. We perform cross-correlation of the SCUBA-2 sample with radio, 24um and 8um catalogues, using a statistical Poissonian method, in order to pinpoint the positions of the sources, as well as with optical data in order to obtain their redshifts. The radio data comes from the MIGHTEE survey, significantly improving the radio depth of our study. The AGN classification is performed by examining the ratio of radio to sub-millimeter emission, providing us with a sample of radio-excess AGNs. This result can be of value to both those trying to estimate the star-forming emission of sub-millimeter sources, where the AGNs are a contamination, and to those interested in the physics of AGNs within the sub-millimeter sample.

Speaker: Bruno Slaus (Astronomical Observatory Institute, Faculty of Physics and Astronomy, Adam Mickiewicz University, ul. Słoneczna 36, 60-286 Pozna´n, Poland)

Wednesday 16 September

Multimessenger

28 Four decades of multi-colour and multi-messenger AGN

I will reflect on my career in AGN research, highlighting the scientific topics I have worked on and, above all, the many colleagues and collaborators with whom I have shared this scientific journey over the years.

Speaker: Dr Paolo Padovani

29 Neutrinos from AGNs

I will review recent results from neutrino observations of AGNs.

Speaker: Dr Chiara Bellenghi (Technical University Munich)

30 Blazars as High-Energy Neutrino Emitters

The discovery of astrophysical neutrinos has opened a new window on the non-thermal Universe, with blazars being among the leading candidate source classes. Their relativistic jets provide favorable conditions for the acceleration of particles to ultra-high energies, potentially producing high-energy neutrinos together with electromagnetic radiation. In this contribution, I will discuss the physical processes responsible for neutrino production in blazars, as well as several individual sources that have been associated with high-energy neutrino emission.

Speaker: Prof. Narek Sahakyan (ICRANET-Armenia IO)

10:40 Coffee break

AGN Jets

31 Uniting optical, gamma-ray, and neutrino data a decade after the first neutrino blazar

For the past decade, the IceCube South Pole observatory has revealed indications of high-energy neutrino emission from blazars, powerful black-hole jets aligned with our line of sight. This supports the theoretical expectation that relativistic jets are efficient hadronic accelerators. However, neutrino data face limited statistics, and state-of-the-art source models suffer from critical degeneracies that limit their predictive power, preventing a confident identification of the neutrino sources. Paolo Padovani's work on the characterization and classification of blazars, including the first neutrino source association, has been central to this effort. In this talk, I will show how a collaboration started at ESO with Paolo Padovani has brought together optical, gamma-ray, neutrino, and theoretical expertise into a single interdisciplinary framework, where numerical source models are directly informed by observations. I will argue that this effort is transforming the role of source models from descriptive to predictive, and that this will be an essential tool for unveiling the most powerful cosmic sources in synergy with the upcoming generation of multi-messenger facilities.

Speaker: Dr Xavier Rodrigues (European Southern Observatory)

32 From Gamma-Ray Absorption Features to Neutrinos: Tracing the Environments of BL Lac Objects

The identification of environmental large-scale structures in active galactic nuclei typically relies on the analysis of absorption and emission lines in their optical spectrum. In BL Lac objects, however, the dominant non-thermal jet emission obscures thermal signatures, making such detections challenging.
Despite this complexity, these environmental photon fields may interact with gamma rays of the blazar jet through gamma-gamma pair production. This interaction reduces the original flux of gamma rays emitted by the source and produces observable absorption features in its spectral energy distribution. Interestingly, assuming protons accelerated in the jet, the same seed photon fields can trigger proton-photon interactions, acting as targets for the production of high-energy neutrinos.
In this contribution, we explore how gamma-ray absorption features in BL Lac spectra provide indirect diagnostics of their environment and may be linked to neutrino emission. Furthermore, we present a set of simulations exploring the optimal physical conditions for the production of neutrino fluxes compatible with the sensitivities of current and upcoming neutrino detectors.

Speaker: Luca Foffano (INAF Rome (IAPS))

33 Multi-messenger emission from AGN jets: Bridging relativistic simulations and observational signatures.

Active Galactic Nuclei (AGN) and their relativistic jets are among the most energetic astrophysical systems, serving as promising sites for particle acceleration and multi-messenger emission. Despite decades of study, the matter composition of AGN jets remains an open question. The particles inside an AGN jet can be accelerated to high energies via different mechanisms, including shocks, stochastic turbulent acceleration, and magnetic reconnection which can generate distinct multi-messenger observational signatures. These signatures can therefore serve as pivotal diagnostic tools for assessing the viability of different jet composition models in explaining the observed multi-messenger emission from AGN jets.

The detection of high-energy neutrinos from the direction of blazars like TXS 0506+056, has renewed the interest in hadronic and lepto-hadronic jet composition models, as these models allow neutrino production through mechanisms involving proton interaction. To connect such multi-messenger observations with realistic jet dynamics, numerical tools are required that can simultaneously evolve relativistic magneto-hydrodynamic (RMHD) flows and non-thermal particle populations.

We have developed a lepto-hadronic multi-zone framework for AGN jets and coupled it with RMHD jet simulations performed using the PLUTO code. This framework has been further extended through our newly developed proton Lagrangian particle module for PLUTO, which augments the existing leptonic particle module. We solve the cosmic ray transport equation and evolve non-thermal proton populations along with lepton populations within the evolving jet. By combining jet dynamics, and different particle cooling and acceleration mechanisms, our framework generates synthetic multi-wavelength photon and neutrino fluxes for different AGN jet scenarios. We apply this framework to disentangle the role of internal shocks and entrainment of proton-rich matter via jet-environment interactions in shaping the resulting photon and neutrino emission signatures. Our framework serves as a bridge between relativistic magneto-hydrodynamic simulations, lepto-hadronic modeling, and multi-messenger observations of AGN jets.

Speaker: Harshita Bhuyan (Max Planck Institute for Astronomy Heidelberg, Indian Institute of Technology Indore)

34 High Energy Particle Acceleration in Shearing Flows

Stochastic Fermi-type particle acceleration has emerged as a compelling mechanism for the efficient energization of particles in supermassive black hole systems. I will discuss recent advances, and exemplarily highlight: (i) the role of shear acceleration in sustaining ultra-relativistic electrons and protons in large-scale jets such as in Centaurus A, (ii) its implications for the production of extended (semi-steady) VHE emission in M87, and (iii) the efficiency of turbulent CR acceleration processes in neutrino-candidate Seyfert galaxies.

Speaker: Frank Rieger (IPP)

12:40 Lunch

AGN Environments

35 When Jets Are Not Enough: Neutrino Emission and Accretion in AGN

AGN have long been regarded as prime candidates for high-energy astrophysical neutrino emission, particularly jetted AGN, which make up about 10% of the population. The association of a neutrino and a neutrino flux excess with the blazar TXS 0506+056 confirmed this expectation and revived the debate on jet particle composition. The multimessenger picture changed significantly when the most intense neutrino excess ever observed by IceCube was linked to the archetype of non-jetted AGN (NGC 1068). This raised the question of how neutrinos can be produced in systems lacking relativistic emitting regions. The most plausible site is the plasma surrounding the central supermassive black hole, namely the accretion flow or its immediate environment.
We therefore initiated a systematic study of the accretion properties of all blazars associated with neutrino emission. I will present a new approach based on optical spectroscopic analysis and indirect accretion emission modeling. Preliminar results point toward similar accretion signatures for all neutrino emitting AGN, consistent with slower-than-standard disks, though not slow enough to imply a fully different accretion structure.
Neutrinos signalling a specific transitional accretion regime, more than being a natural product of relativistic jets, may mark a major shift in our understanding of AGN physics.

Speaker: Tullia Sbarrato (INAF - Osservatorio Astronomico di Brera)

36 Kinetic simulations of mildly relativistic weakly magnetized shocks in AGN jets

Plasma shock waves are among the most promising sites for efficient particle acceleration in extragalactic jets. In mildly relativistic electron–ion shocks, electrons can be heated to high Lorentz factors, providing a natural explanation for the large minimum electron energies often required to model the emission of BL Lac objects (Arbet-Engels et al. 2025). In this work, we present results from particle-in-cell (PIC) simulations of mildly relativistic weakly magnetized shocks, covering a broad range of shock Lorentz factors (γ = 1.5–16), magnetizations (σ = 10⁻⁴–0.1), and shock obliquities. We investigate ion-to-electron energy transfer, magnetic field amplification, and particle acceleration, and their dependence on upstream shock parameters. Finally, we discuss the implications of these results for multiwavelength emission modeling.

Speaker: Artem Bohdan (Max Planck Institute for Plasma Physics)

37 Numerical Simulations of Restarted Jets: Dynamics, Particle Acceleration, and Emission

Radio observations of restarted jets in active galaxies reveal complex morphologies and spectral signatures that trace episodic jet activity. We investigate these phenomena using high-resolution 3D simulations with the PLUTO code, combined with Lagrangian macroparticles to model non-thermal electrons. This framework enables spatially resolved modelling of synchrotron emission, spectral index, and polarization over a broad range of radio frequencies. Our simulations show that, after jet shutdown, cocoon emission fades rapidly. When the jet restarts, it propagates through the cavity left by the previous activity, producing new compact emission within the older diffuse cocoon. We find that the main particle acceleration sites depend on jet power and magnetization, with forward shocks dominating in some cases and internal shocks in others. We find that the remnant cocoon conditions can disrupt the bow shock. We also identify new transient emission features when the restarted jet breaks out of the old cocoon. In addition, the new jet shows stronger depolarization than the old cocoon. The simulated emission, spectral index, and polarization maps closely resemble observations. These results provide new insights into jet duty cycles, particle acceleration, and radiative ageing in restarted radio galaxies.

Speaker: Prathamesh Ratnaparkhi (IUCAA, Pune, India)

38 Changing Accretion in AGN within the Disc–Wind Framework

We present a multiwavelength study of 798 Type 1 and 2607 Type 2 active galactic nuclei (AGN), combining optical spectroscopy with X-ray data from eROSITA and infrared observations from WISE. We investigate a scenario in which AGN accretion can weaken, disappear, and reform, driving structural changes across the nucleus with characteristic timescales. We find ~1000 low luminosity optically selected Type 2 AGN that are not detected in X-rays. Most of these non-detections cannot be explained by survey limits or obscuration, suggesting that their X-ray emission is intrinsically very weak or missing. A subset may represent a candidate true Type 2 AGN. We also show that standard WISE colour selection is biased toward luminous Type 2 AGN, missing many lower-luminosity systems. Our results support a disc–wind framework in which AGN classification depends not only on orientation, but also on luminosity-driven structural evolution.

Speaker: Sruthi Suresh (University of Melbourne)

16:10 Coffee break

AGN Environments

39 Probing Obscured AGN with Far-Infrared Line Emission: Predictions from Multiphase ISM Modeling

The far-infrared (FIR) regime offers a unique, dust-penetrating window into AGN activity that is inaccessible to X-ray, optical, and radio surveys. While multi-wavelength approaches have been transformative for unobscured AGN demographics, the heavily obscured population (believed to dominate at cosmic noon) remains poorly characterized. FIR fine-structure lines are powerful obscuration-independent AGN tracers, yet physically-motivated predictions for their emission in AGN-host galaxies are largely absent from the literature. We present predictions for FIR line emission from AGN-host galaxies using SLICK, a multiphase ISM post-processing framework, applied to the IllustrisTNG cosmological simulations. SLICK combines DESPOTIC for the molecular phase with Cloudy for the ionized phase, incorporating AGN radiation fields self-consistently from TNG black hole accretion rates. The framework models the full suite of FIR fine-structure lines such as [OIII] 88µm, [NII] 122/205µm, [CII] 158µm, [OI] 63µm, and the CO ladder, simultaneously across ISM phases, enabling physically-motivated decomposition of line emission into AGN and star-formation contributions. We validate SLICK against observed FIR line luminosities from nearby QSOs and LIRGs to high-z galaxies, and present physically-motivated predictions for AGN-host galaxies across a range of Eddington ratios and redshifts. Our results will inform survey strategy for PRIMA, the proposed FIR probe mission, providing concrete recommendations for line selection and sensitivity requirements to conduct a census of AGN across cosmic time, including the heavily obscured population inaccessible to shorter wavelengths.

Speaker: Karolina Garcia (NCSA, University of Illinois)

40 AGN Activity and Multi-Phase Gas in Overdense Structures at z~2-4

Overdense cosmic structures at high redshift (z~2-4) offer a unique laboratory to study the baryon cycle during the peak of galaxy assembly. This work connects the environmental impact of massive structures with the microscopic physical state of the circumgalactic medium (CGM) through a two-fold approach. First, we investigate the MQN01 protocluster, an exceptionally dense region hosting a giant, extended Lya nebula. Utilizing deep Chandra X-ray data, we examine the origin of this extended emission, revealing one of the densest and most luminous populations of AGNs ever observed at these redshifts, which acts as a primary ionizing source. Furthermore, around the brightest central AGN in the main core, we detect extended X-ray emission. A detailed investigation confirms its thermal origin, marking a direct detection of a nascent proto-Intracluster Medium (proto-ICM) and providing a rare glimpse into how the ICM forms. This system also offers a prime environment to study the co-spatial interplay between the hot and cold gas phases. Crucially, the survival and high clumpiness of the cold gas phase are strictly tied to the high pressure exerted by the surrounding hot, thermal phase. To systematically constrain this density structure and clumping factor, we then expand our analysis to a large sample of 39 quasar halos spanning z~2.1-4.5. By leveraging a powerful combination of Keck/KCWI, Keck/MOSFIRE, and VLT/MUSE data, we overcome the resonant limitations of Lya through the detection of non-resonant HeII and Ha extended emissions. Comparing the observed HeII/Ha and Lya/Ha line ratios with CLOUDY photoionization models assuming log-normal gas density distributions, we find that the high-redshift CGM is highly clumpy (clumping factors Cint > 100) and multi-phase, where dense cold gas (nH ~ 10^-1 cm^-3) is pressure-confined by the hot phase and illuminated by an ionizing spectrum. Together, these studies bridge the gap between large-scale environmental feedback from AGN and the small-scale multiphase physics of the cosmic web.

Speaker: Andrea Travascio (INAF)

Thursday 17 September

AGN Feedback

41 AGN feedback: a multi-phase and multi-scale challenge

AGN feedback is a complex problem. It involves multiple spatial scales, multiple gas phases and mass scales, multiple physical processes and timescales. Recent progress has been accelerated by an increase in both computational developments and observational facilities. The past years have witnessed the dawn of a new range of sub-grid models for AGN feedback, incorporated into ever-more-detailed cosmological simulations. Observationally, great progress has been made in characterizing the demographics of AGN driven outflows and jets using Integral Field Spectrographs from the ground and sub-mm and radio interferometers.

I will review where we stand in this field and future directions, linked also to upcoming new observational facilities.

Speaker: Vincenzo Mainieri (ESO)

42 Blue LERGs and a Missing Evolutionary Axis in Radio-AGN Unification: Small-Scale Jets, Mergers, and Warm Molecular Gas

Blue low-excitation radio galaxies (BLERGs) may expose a missing evolutionary axis in radio-AGN unification. In the canonical picture, low-excitation radio galaxies are powered by radiatively inefficient accretion in massive, quiescent hosts, where mechanical feedback suppresses cooling and star formation. BLERGs break this expectation: they retain ongoing star formation and substantial cold-gas reservoirs while already hosting radio activity. They therefore provide a rare test of whether radio-AGN diversity reflects only accretion mode and orientation, or whether some systems are caught during a short-lived transition into maintenance-mode feedback. We present new Gemini/GNIRS near-infrared spectroscopy of eight low-redshift (z<0.1) BLERGs, combined with Pan-STARRS optical morphologies and VLASS radio continuum imaging, to investigate the origin of warm molecular gas excitation and the evolutionary state of their radio activity. We detect warm H$_2$ emission with characteristic excitation temperatures of T~2000-4000 K and luminosities comparable to those of radio-emitting early-type galaxies. However, the H$_2$ emission shows no clear positive dependence on radio power. Instead, the strongest H$_2$ emission occurs in morphologically disturbed systems, while VLASS imaging reveals compact and small-scale radio morphologies (<20 kpc) consistent with young, localized, or recently restarted jets. These results suggest that BLERGs occupy a phase in which merger-driven gas inflows and early-stage mechanical feedback coexist before radio feedback has fully coupled to the host halo leading to quiescence. In this framework, BLERGs are not merely outliers within the radio-galaxy AGN population, but possible precursors to classical maintenance-mode systems. They provide a low-redshift laboratory for testing how radio-AGN unification must be extended to include gas supply, host-galaxy evolution, and local environment. Future Roman and Euclid spectroscopy, combined with deep radio continuum imaging, will enable statistically significant BLERG samples across cosmic time, testing how compact jets, cold gas, and environment shape the emergence of radio-mode feedback.

Speaker: Swetha Sankar (Johns Hopkins)

43 The Properties and Morphology of Highly Ionized Coronal Line Outflows in Nearby Jetted AGN

Active galactic nuclei (AGN) drive multiphase outflows via both radiative and jet modes. While these outflows are extensively studied using traditional tracers—such as [O III] for ionized gas and H₂ or CO for molecular gas—and ultra-fast outflows (UFOs) are identified via extreme X-ray absorption, the intermediate-to-high ionization phase remains poorly understood. This regime (up to $\sim 300\text{ eV}$) is energetically more significant than the [O III]-traced component but less extreme than UFOs. Tracing it requires broad optical-to-infrared spectral coverage, as optical high-ionization coronal lines are intrinsically faint and rarely detected in jetted AGN.In this work, we search for coronal line outflows using [Fe VII] and [Fe X] lines across a sample of nearby jetted AGN. We detect strong coronal emission lines in 11 sources, revealing a morphology distinct from that of low-ionization lines. By combining spatially resolved optical data with high-resolution L- and C-band VLA radio observations, we find that while these highly ionized structures extend along the jet axis in a few sources, they remain compact in others. Additionally, using archival JWST data for two sources, we confirm the presence of highly ionized outflows via multiple infrared coronal emission lines.Finally, we compare the morphology of these high-ionization outflows against larger radio jet structures extending up to several hundred kiloparsecs. While low-ionization outflows tend to align closely with the jet axis and exhibit extended structures, highly ionized outflows are typically more confined to the nuclear regions and do not strictly follow the jet direction. This suggests that less powerful jets may more efficiently drive or enhance low-ionization outflows compared to their highly ionized counterparts.

Speaker: Payel Nandi

11:10 Coffee break

AGN Evolution

44 Blazar Jets Through Cosmic Time: Tracing the Evolution of the Universe's Powerhouses

Blazar jets are among the most powerful particle accelerators in the Universe and provide a unique window into the growth of supermassive black holes across cosmic time. By tracing the evolution of blazar populations, we can investigate the connection between jet production and the rapid assembly of the earliest supermassive black holes, test whether the properties and power of relativistic jets evolve with redshift, and constrain the origin of the cosmic high-energy backgrounds. In this talk, I will review recent advances in our understanding of blazar evolution from X-ray and γ-ray surveys, highlighting implications for jet power, black hole–jet co-evolution, and the composition of the cosmic X-ray and γ-ray backgrounds. I will also discuss future prospects for blazar evolution studies with upcoming high-energy observatories, including COSI and CTAO.

Speaker: Lea Marcotulli (DESY Zeuthen)

45 Black hole - host galaxy coevolution in IMBH regime as seen by Hubble Space Telescope

There are two primary channels of SMBH growth: accretion of infalling material and galaxy mergers that lead to the mergers of their central black holes. The latter growth pathway results into the scaling relations between central black hole mass and intrinsic properties of the host galaxy (e.g., bulge stellar mass (Mbulge), velocity dispersion of stars in the bulge).
Our goal is to extend these scaling relations to the low-mass end (Mbh <1M MSun, including intermediate-mass black holes Mbh <200k MSun). We have identified a sample of such objects through data mining of the SDSS spectroscopic sample. We observed over 70 host galaxies with Mbh < 200k MSun from this sample using the Hubble Space Telescope. Given its unprecedented spatial resolution, we derived total bulge stellar masses from detailed 1D/2D photometric decomposition.
Our results demonstrate that host galaxies of AGN powered by low-mass BHs follow the same scaling relations established for more massive SMBHs. This supports the scenario of BH–host galaxy co-evolution even in the low-mass regime, predominantly indicating that major mergers remain a dominant growth channel. Furthermore, we did not find any difference in the behavior of the Mbh–Mbulge scaling relation between low- and high-accretion-rate subsamples of galaxies.

Speaker: Kirill Grishin (LUX, Paris Observatory)

Concluding remarks

12:40 Lunch