15.01.2026

TBD

Joint Journal Club

TBD -------------------------------------------------------------------------------------------------------------------------------------------------------- Meeting ID: 86081722826 Password: 9833 Scheduled time: 15/01/2026 10:30 CET (09:30 UTC) Duration: 120 minutes Meeting link: https://us02web.zoom.us/j/86081722826?pwd=4szYdJKahhMatLXcDrqyuMMHIeHnnP.1 --------------------------------------------------------------------------------------------------------------------------------------------------------

04.02.2026

Alessandro Ignesti

Unveiling the physics of ram pressure stripping: New insights from GASP

Jellyfish galaxies, characterised by long filaments of stripped interstellar medium extending from their disks, are prime laboratories to study the results of ram pressure stripping in galaxy clusters and to explore the astrophysics of galaxies under extreme conditions. I will present a series of recent results in this field made by the GASP (GAs Stripping Phenomena in galaxies with MUSE) team based on a multi-wavelength survey of ram-pressure-stripped galaxies. Using a combination of LOFAR and MUSE observations, we have explored how the non-thermal components of the interstellar medium, namely magnetic fields and cosmic rays, evolve under the influence of ram pressure. First, I will show how we can use the stripped ionised plasma tails to probe the intracluster medium microphysics. Then I will provide an overview of how LOFAR has changed our understanding of the non-thermal radio emission observed in these galaxies and how the extraplanar magnetic field can regulate the interplay between the stripped interstellar medium and the surrounding intracluster medium. Finally, I will discuss the future perspectives in the upcoming SKA era.

09.03.2026

Taj Jankovič

Radiation-hydrodynamics of star–disc collisions for quasi-periodic eruptions

Quasi-periodic eruptions (QPEs) are recently discovered transients of unknown nature occurring near supermassive black holes, which feature bright X-ray bursts separated by hours to days. A promising model for QPEs is the star-disc collisions model, where a star repeatedly interacts with an accretion disc around a black hole, creating shocks that expel dense outflows of gas from which radiation emerges. We investigate the dynamics of the star-disc collisions, the properties of the outflows, and the resulting radiation signatures. Our study focuses on the generic case where the star remains unperturbed by the collision and the stellar crossing time through the disc is sufficiently long for shocked gas to flow around the star. We performed a three-dimensional radiation-hydrodynamics simulation of the star-disc collision. The star was modeled as a solid, spherical body, and the interaction was simulated for a small, local section of the accretion disc. We found that star–disc collisions generate a nearly paraboloidal bow shock. The heating of gas is not confined to the column of gas directly ahead of the star but also extends laterally as the shock front expands sideways while traveling with the star. As the star crosses the disc, it injects momentum preferentially along its direction of motion, leading to an asymmetric redistribution of energy and momentum. As a result, two outflows emerge on opposite sides of the disc with different properties: the forward outflow expands faster, contains more mass, carries more energy, and is about twice as luminous as the backward outflow. Our findings suggest that the asymmetry in outflow properties and luminosity arises naturally from the collision dynamics, offering a possible explanation for the alternating "strong–weak" flare patterns observed in several QPE sources.

19.03.2026

Shilpa Sarkar & Richard Wunsch

Joint Journal Club (Sporilov and via Zoom)

>> From the Stellar department, Shilpa Sarkar will present the paper: "Global Structure of Accretion Flows in Sgr A*": https://arxiv.org/abs/2603.03996 =================================================================================== >> From the Galaxies department, Richard Wunsch will present the paper: "The PHANGS-MUSE/HST-Hα nebulae catalogue: Parsec-scale resolved structure, physical conditions, and stellar associations across nearby galaxies" =================================================================================== Meeting ID: 81888620962 Password: 9540 Link: https://us02web.zoom.us/j/81888620962?pwd=zTuhRAC1h6cZeZEZ6bbVjXCyE6KodJ.1 ---------------------------------------------------------------------------------------------------------------------------------------------------

01.04.2026

Nushkia Chamba

Across the Faint Universe: How Deep Images Reveal The History of Galaxies Big and Small

As galaxies form and evolve in the Universe, they leave behind a complex trail of ultra-faint stars and gas in their outskirts. This faint material holds clues to the growth and accretion history of galaxies. In this colloquium, we present some of the deepest images of the faint universe, of dwarf and massive galaxies, as seen in X-ray, optical and radio wavelengths. We discuss how these images help us understand the key physical and environmental processes such as star formation, feedback and mergers that drive the growth of galaxies big and small. These results demonstrate the importance of preserving low surface brightness structure in the next generation of surveys from Euclid, Rubin-LSST, Roman and SKA in order to further our understanding of galaxies across the Universe.

08.04.2026

Lýdia Štofanová

From atoms to the cosmos:

Our Universe, more specifically, the warm-hot intergalactic medium in the cosmic web filaments, the intra-cluster medium of galaxy clusters, and the circum-galactic medium around individual galaxies is full of such metals. By studying the medium of these massive astrophysical objects through spectroscopy, and by studying the impact of different feedback processes on the metal transport on various physical scales, we can get closer to the understanding of the origin and evolution of metals in some of the most massive objects in our Universe. In this talk I will give an overview of my Ph.D. thesis, which focused on the spectroscopy of the cosmic web (filaments and galaxy clusters) with current and future X-ray telescopes like e.g. NewAthena. I will show that future X-ray micro-calorimeter missions will be sensitive to effects that have not yet been detected before, like for example observing WHIM in absorption against bright cool-core clusters. I will briefly mention the importance of updating the atomic databases and plasma codes in the X-ray regime. In the past two years, I shifted my career towards the space industry, more specifically, over time I got more involved in the QUVIK mission - the very first Czech-led space telescope for which I recently accepted a role of the main project manager. I will briefly mention updates about QUVIK. I will also briefly talk about the new science public outreach activities that we are preparing in Brno together with my colleagues.

14.04.2026

Lýdia Štofanová

From atoms to the cosmos

Our Universe, more specifically, the warm-hot intergalactic medium in the cosmic web filaments, the intra-cluster medium of galaxy clusters, and the circum-galactic medium around individual galaxies is full of such metals. By studying the medium of these massive astrophysical objects through spectroscopy, and by studying the impact of different feedback processes on the metal transport on various physical scales, we can get closer to the understanding of the origin and evolution of metals in some of the most massive objects in our Universe. In this talk I will give an overview of my Ph.D. thesis, which focused on the spectroscopy of the cosmic web (filaments and galaxy clusters) with current and future X-ray telescopes like e.g. NewAthena. I will show that future X-ray micro-calorimeter missions will be sensitive to effects that have not yet been detected before, like for example observing WHIM in absorption against bright cool-core clusters. I will briefly mention the importance of updating the atomic databases and plasma codes in the X-ray regime. In the past two years, I shifted my career towards the space industry, more specifically, over time I got more involved in the QUVIK mission - the very first Czech-led space telescope for which I recently accepted a role of the main project manager. I will briefly mention updates about QUVIK. I will also briefly talk about the new science public outreach activities that we are preparing in Brno together with my colleagues.

17.04.2026

Masafumi Imai et al.

Connecting Radio Groups: Astronomy, Solar System Science, and Outreach

An informal meeting of the radio groups at ASU and the Institute of Atmospheric Physics to discuss the use of radio observations in astronomy and space science, including solar radio research and Jovian science, the involvement in the international infrastructures LOFAR, ALMA, as well as local radio instrumentation in Ondřejov. The seminar will also explore the outreach potential of portable radio antennas, including an LWA antenna and a CubeSat cardboard Yagi antenna, and discuss possibilities for future collaboration.

17.04.2026

Eliška Kleinová

Interpreting an Accretion Disk Look-Alike in JWST Imaging

Deep imaging with the James Webb Space Telescope is revealing a growing number of faint and morphologically complex sources whose nature is not immediately clear. In this talk, we focus on a peculiar extended object identified in the field of WR-124, which at first glance exhibits an unusually elongated structure reminiscent of an accretion disk around a supermassive black hole. We analyze multi-wavelength imaging from the MIRI and NIRCam instruments and perform aperture photometry to estimate the source brightness and angular size (~1 × 1.5 arcsec). Using spectral energy distribution fitting, we constrain its physical properties and find a likely redshift of z ≈ 0.8. Based on the combined photometric and morphological analysis, we consider possible interpretations of the object, in particular a galaxy merger or a gravitational lensing configuration. We present the methodology used to derive these constraints and discuss the limitations of the current data in distinguishing between these scenarios.

24.04.2026

Mattia Pacicco

Magnetised bubbles across scales: from supernova remnants to the Local Bubble - with 3D MHD simulations

Magnetised bubbles pervade the interstellar medium across a vast range of scales, from individual supernova remnants (SNRs) to the superbubbles they collectively inflate. We present two complementary 3D magnetohydrodynamic studies tracing this hierarchy from its smallest building blocks to its most prominent local example. We simulate SNRs expanding into a non-homogeneous, magnetised two-phase medium, obtaining complex magnetic field configurations in their interiors. Strongly magnetised remnants develop magnetically confined hot cavities surrounded by a diffuse magnetised halo, and remain orders of magnitude more X-ray luminous than their weakly magnetised counterparts. We then extend our study to larger scales, simulating the Local Bubble: a superbubble encasing the Solar neighbourhood, whose expansion has been driven by numerous supernovae. We characterise its turbulent interior magnetic field and its amplification in the shell, while also modelling neighbouring superbubbles and SNRs within 1 kpc of the Sun. Together, these parsec- to kiloparsec-scale frameworks give us insights on the coupling between magnetic fields and stellar feedback, from individual remnants to the large-scale cavities structuring the local interstellar medium.

28.05.2026

Michalis Kourniotis and Alessandro Ignesti

Joint Journal Club (Sporilov and via Zoom)

>> From the Stellar Department Michalis Kourniotis will present the paper : "The dramatic transition of the extreme red supergiant WOH G64 to a yellow hypergiant", https://www.nature.com/articles/s41550-026-02789-7 >> From the GPS Department Alessandro Ignesti will present the paper : "The Impact of Ram Pressure on the Radio Spectral Index and Magnetic Field of NGC 4522: A High-resolution VLA Continuum Study", https://ui.adsabs.harvard.edu/abs/2026ApJ...999..116C/abstract ========================================================================== Meeting ID: 88035534277 Password: 7409 Link: https://us02web.zoom.us/j/88035534277?pwd=vy3qSoUtYcJU69bYTdsf91A0pK8Twb.1 Scheduled time: 28/05/2026 10:30 CEST (08:30 UTC) ==========================================================================

28.05.2026

Samik Mitra

Importance of low angular momentum magnetised accretion flows around Sgr A*

Accretion onto Sgr A* is often discussed in terms of SANE and MAD models, where the flow is described as a turbulent, rotationally supported magnetised disk. In this talk, I will instead focus on a complementary semi-analytical picture: low angular momentum magnetised accretion. In this regime, the gas has too little angular momentum to form a Keplerian disk, so the dynamics are dominated by radial infall, weak rotation, magnetic pressure, and gravity. Even modest angular momentum can create a centrifugal barrier close to the black hole, where the supersonic inflow may undergo shock formation, producing a hot, compressed post-shock region. This gives the flow a more quasi-spherical and transonic character, distinct from the disk-like SANE/MAD paradigm. Using semi-analytical models, one can follow how the shock location, compression ratio, velocity, density, and magnetic-field strength depend on the flow parameters. I will discuss how such low angular momentum solutions provide a physically motivated framework for understanding magnetic-field amplification, dissipation, and possible flare-like activity near Sgr A*, and why they may be important alongside fully numerical GRMHD disk models.

15.06.2026

Abhishek Paswan

Starburst galaxies contributing to cosmic reionization

One of the outstanding problems of our present observational cosmology is to understand the nature of sources that play a crucial role in the re-ionization of our early universe by leaking their bulk of ionizing photons. In this context, I will first present a low-mass, high-redshift, starburst galaxy identified as an extreme Lyman Continuum (LyC) photon leaker. Using their local counterparts (i.e., Green Peas and Blueberries), I will also discuss the physical processes in greater detail that allow such galaxies to leak their ionizing LyC photons.

19.06.2026

Abhishek Paswan

Starburst galaxies contributing to cosmic reionization

One of the outstanding problems of our present observational cosmology is to understand the nature of sources that play a crucial role in the re-ionization of our early universe by leaking their bulk of ionizing photons. In this context, I will first present a low-mass, high-redshift, starburst galaxy identified as an extreme Lyman Continuum (LyC) photon leaker. Using their local counterparts (i.e., Green Peas and Blueberries), I will also discuss the physical processes in greater detail that allow such galaxies to leak their ionizing LyC photons. Meeting ID: 84708295405 Password: 3128 Link: https://us02web.zoom.us/j/84708295405?pwd=1WZxwh8TZBK6bS2KBYkIdaNaQMqYi2.1 Scheduled time: 19/06/2026 11:00 CEST (09:00 UTC)

25.06.2026

Brankica Kubatova and Václav Pavlík

Joint Journal Club (Sporilov and via Zoom)

=================================================================================== From the Stellar department, Brankica Kubatova will present the paper: "On the Robustness of Bi-Stability Jump Predictions": https://arxiv.org/pdf/2606.17130 ----------------------------------------------------------------------------------- From the Galaxies department, Václav Pavlík will discuss his EAS conference presentation" "A review talk on Star Forming regions" =================================================================================== Zoom link: Meeting ID: 82546654674 Password: 4359 Link: https://us02web.zoom.us/j/82546654674?pwd=4haRAateALXpDwQyLOMAT5F2XljHZA.1 Scheduled time: 25/06/2026 10:30 CEST (08:30 UTC) ===================================================================================

01.07.2026

Milos Ertola Urtubey

Dynamical Black Holes in the Inflationary Epoch

In general relativity, black holes are most commonly described by stationary geometries, such as Schwarzschild and Kerr spacetimes. These represent isolated objects in asymptotically flat backgrounds. These solutions, however, neglect the effects of cosmological expansion, which could be significant for black holes formed in the early universe. Dynamical black hole spacetimes coupled to cosmological backgrounds provide a framework through which this issue can be addressed. In this talk, I discuss how black holes evolve during the inflationary epoch, assuming they are dynamically coupled to the cosmological expansion via a generalised McVittie geometry. The combined effects of cosmological coupling, Hawking evaporation and radiation accretion during the subsequent cosmic eras (inflation, radiation, matter and dark energy) are analysed. Requiring the black hole event horizon to remain smaller than the particle horizon at all times yields an upper bound on the mass parameter. Radiation accretion during the radiation era further constrains the parameter space to prevent runaway growth, while Hawking evaporation sets a lower bound on the initial mass to ensure survival through inflation. These findings suggest that only black holes formed within a specific initial mass range during inflation can persist to the present day, achieving a maximum mass of ~ 0.001043 Solar masses.

15.07.2026

Prof. Prajval Shastri

Beyond being Cosmic Beacons:
Insights on the Role of Accreting Supermassive Black Holes in Galaxy Assembly from the Story at z~0

Supermassive black holes (SMBH) that are found in the centres of most galaxies comply with scaling relationships that imply hand-in-hand growth of the SMBH and its galaxy bulge, which in turn implies that the SMBHs play a significant role in regulating galaxy assembly. SMBHs grow via coalescence as a consequence of their host galaxies merging or due to accretion. Our current broad understanding is that the SMBHs influence star formation via the consequences of accretion, which enables them to impact their environments out to spatial scales that are well beyond their gravitational sphere of influence. However, the exact mechanisms and the circumstances under which positive and negative feedback dominate remain elusive. I will describe a multi-frequency investigation of the imprints if any at very nearby redshifts of this feedback between the accretion around the SMBH and star formation in the host galaxy.

12.08.2026

Biswaraj Palit

State transitions in Changing-Look AGNs

The changing-look (CL) behavior in active galactic nuclei (AGNs) is characterized by dramatic fluctuations in the overall brightness of sources, leading to restructuring of circum-nuclear environments such as the inner accretion geometry, broad line region (BLR), and outflows. They offer a rare opportunity to witness accretion state transitions in real time, akin to those seen in stellar-mass X-ray binaries (XRBs). In this talk, I will present a decade-long multiwavelength study of the Seyfert galaxy, which captures a complete spectral state transition--from a faint, hard X-ray phase to a bright, UV- and soft X-ray-dominated state within just ~10 years. Using diagnostics like the X-ray loudness parameter and the hardness-intensity diagram, we identify a critical Eddington ratio (~ 0.02) marking the onset of inner accretion flow restructuring. These findings provide strong evidence that CLAGNs trace accretion physics analogous to XRBs, scaled up in mass but compressed in time.

23.08.2026

Emel Altas

New Approach to Conserved Charges of Generic Gravity in AdS

Starting from a divergence-free rank-4 tensor of which the trace is the cosmological Einstein tensor, we give a construction of conserved charges in Einstein's gravity and its higher derivative extensions for asymptotically anti-de Sitter spacetimes. The current yielding the charge is explicitly gauge-invariant, and the charge expression involves the linearized Riemann tensor at the boundary (Phys. Rev. D 99, 044016, 2019).

28.08.2026

Teodora Darie

SED Fitting of Youngest Galactic Fountain Candidate in the Pinwheel Galaxy (M101)

Spiral galaxies such as the Pinwheel Galaxy (M101) regulate their star formation via massive stellar feedback. Using JWST/NIRCam data in 6 different filters spanning 0.9–4.4 μm, we perform aperture photometry and spectral energy distribution (SED) analysis on a region, previously known to be an expanding supershell (Kamphuis et al., 1991) and recently confirmed as a high-confidence site of galactic fountain in M101 (Anitha Shaji et al., 2025). Out of all 9 fountain sites identified in the latter work, this region hosts the youngest and most energetic fountain, presenting traces of recent star formation. By taking the photometric fluxes of the observational data and using CIGALE (Code Investigating GALaxy Emission) software, we model the stellar population, nebular emission, dust attenuation, and dust emission associated with this region to investigate the underlying and/or contagious star formation.

31.08.2026

Emel Altas

New Approach to Conserved Charges of Generic Gravity in AdS

Starting from a divergence-free rank-4 tensor of which the trace is the cosmological Einstein tensor, we give a construction of conserved charges in Einstein's gravity and its higher derivative extensions for asymptotically anti-de Sitter spacetimes. The current yielding the charge is explicitly gauge-invariant, and the charge expression involves the linearized Riemann tensor at the boundary (Phys. Rev. D 99, 044016, 2019).

30.09.2026

Maïmouna Brigitte

Multiwavelength study of accreting black holes in X-ray Binaries (Ph.D. Thesis discussion)

Black hole X-ray binaries are key laboratories for studying accretion physics and strong-field gravity. As matter is transferred from a donor star to the black hole, it forms a hot, rotating accretion disk that emits intense X-ray radiation. During outbursts, these systems brighten dramatically and evolve through distinct accretion states. Yet, their accretion geometry and wind structure remain poorly constrained. This thesis investigates accretion and emission processes in X-ray binaries using high-resolution spectroscopy, X-ray timing analysis, and polarimetry. Optical spectroscopy of the high-mass X-ray binary Cygnus X-1, obtained with the 2m Perek telescope, separates the donor star’s photospheric contribution from its stellar wind. The results reveal a clumpy wind with clear dependence on orbital phase and accretion state, and a strong anti-correlation with X-ray emission from the accretion disk. Timing analysis of the low-mass X-ray binary Swift J1727 identifies quasi-periodic oscillations during a rare soft-to-hard spectral transition, tracing variability propagation through the accretion flow at low luminosity. Finally, X-ray polarimetry of five systems constrains coronal geometry, with one source showing signatures consistent with strong-gravity light bending. Together, these results provide new constraints on wind–disk coupling, coronal structure, and accretion geometry in black hole X-ray binaries through a multi-wavelength approach.

01.10.2026

Jorge Velazquéz Casares

The Galactic population of accreting black holes

The Milky Way is thought to be populated with ~10**3-10**4 stellar-mass black holes (BHs) that are fed by gas accreted from companion stars in tight orbits. Most of these BHs are transient and exhibit episodic X-ray outbursts on decadal timescales - the smoking gun that led to their discovery. However, since their duty cycles are very low, the vast majority remain hidden in a dormant state, awaiting to be discovered. Here I present the current census of such transient BH X-ray binaries, summarize their observed properties and discuss new avenues to increase the size of the known population.

01.10.2026

Victoria Grinberg

X-raying the winds of massive stars using high mass X-ray binaries

We are made of stardust—or, at least in significant parts, of material processed in stars. Hot, massive giant stars can drive the chemical evolution of galaxies and trigger and quench star formation through their strong winds and their final demise as supernovae. Yet optical and X-ray measurements of the wind mass loss strongly disagree and can only be reconciled if the winds are highly structured, with colder, dense clumps embedded in a tenuous hot gas. In (quasi-)single stars, however, wind properties are inferred for the whole wind ensemble only; no measurements of individual clumps or clump groups are possible, limiting our understanding of wind properties and launching and therefore of massive stars themselves. Luckily, nature provides us with perfect laboratories to study clumpy winds: high mass X-raybinaries. The radiation from close to the compact object is quasi-point like and effectively X-rays the wind, in particular the clumps crossing our line of sight. In this talk, I will discuss how we can use a variety of observations to constrain the wind properties in bright high mass X-ray binaries in particular focussing in advances from recent ears as done by the X-wind collaboration. Time- and absorption-resolved high resolution X-ray spectroscopy reveals the composition of the multicomponent wind plasma, the structure of the accretion wake, and the wind's response to changes in irradiation. New simulations of wind accretion pave the way towards constraining clump properties from stochastic variability of absorption. New X-ray telescopes such as XRISM and future instruments such as NewAthena will revolutionise the field, allowing us to observe individual clumps in bright sources and, for the first time, make faint sources accessible for high resolution spectroscopy.

12.10.2026

Joseph Gelfand

Multi-Scale Multi-wavelength Investigation of AGN Outflows

Active Galactic Nuclei (AGN) are an essential component of current theories of galaxy evolution. Specifically, the energy released by material accreting onto the central supermassive black hole (SMBH) is believed to generate outflows which suppress star formation throughout the host galaxy. However, the mechanisms by which activity in the central parsecs of a galaxy impacts gas thousands of times further away is poorly understood. To better understand the physics of "AGN feedback," and its various manifestations, we have begun a multi-scale, multi-wavelength investigation of AGN outflows in a sizable and diverse sample of relatively nearby galaxies. In this talk, I will discuss this project and present our initial findings -- including a "bonus" discovery of the interaction between an AGN jet and a satellite galaxy.

12.10.2026

Ingyin Zaw

Black Holes in Low Mass Galaxies

There is ample evidence that supermassive black holes (SMBHs) exist in the nuclei of all massive galaxies and that the masses of the SMBHs scale with properties of their host galaxies, e.g. stellar velocity dispersion (M_BH - σ*), bulge mass (M_BH - M_Bulge), and stellar mass (Μ_ΒΗ - Μ_*). These scaling relations are believed to be the result of co-evolution between the SMBH and its host galaxy. However, the situation in low mass and dwarf galaxies is less clear, with large uncertainties in both the occupation fraction and scaling relations. In addition, if the relations hold true, low mass galaxies should host intermediate mass black holes (IMBHs). Understanding black holes in low mass galaxies is crucial for understanding galaxy evolution, formation of seed black holes in the early universe, and the search for IMBHs. In this talk I will discuss the low mass end of the BH-galaxy scaling relations and search for IMBHs with a focus on a peculiar galaxy, IC 750, a near-by low mass galaxy. I will present a multi-wavelength study of IC 750 which shows that it hosts a 1 x 10^5 M_sun black hole which is undermassive by one to two orders of magnitude below the BH-galaxy scaling relations. I will also show results on the accretion processes in the system and summarize searches for other such systems. I will conclude with the implications of these results on theories of BH-galaxy co-evolution and future prospects.

15.10.2026

Jiri Kubat & TBD

Joint Journal Club (Sporilov & Zoom)

TBD

19.10.2026

Carolina Andonie

A panchromatic view of infrared quasars: revealing their role in evolutionary scenarios

Quasars are the most luminous subset of the Active Galactic Nuclei (AGN) population and represent the most rapid phase of supermassive black hole (SMBH) growth. Strong observational evidence supports a connection between SMBH accretion and the evolution of their host galaxies, where obscured quasars are expected to play a key role. However, this role has not yet been fully understood since large quasar samples have biases, typically against obscured AGN, low-luminosity AGNs, etc. In this talk, I will present results from a complete and unbiased sample of high-luminosity mid-infrared quasars at z=1−3. By combining multiwavelength data from X-rays to radio wavelengths, including ALMA submillimeter observations, we probe the physical properties of both the AGN and their host galaxies, revealing fundamental differences in the radio and star-formation properties between obscured and unobscured populations. I will discuss how these findings challenge the standard AGN orientation model and point toward possible evolutionary links among quasar populations. With the objective of pushing forward obscured quasar research, I will then introduce and show the first results of the 4MOST IR AGN survey, the first large-scale optical spectroscopic survey targeting obscured IR AGN. I will finish my talk by discussing how upcoming multiwavelength large-scale surveys will allow us to improve our understanding of the relationship between different AGN populations and galaxies.

19.10.2026

Briavel Laloux

The impact of AGN emission on SED-derived physical properties with Euclid

Understanding the co-evolution of active galactic nuclei (AGN) and their host galaxies requires the robust decomposition of their respective emission to reliable constrain the AGN and host galaxy physical properties. Leveraging the unique NIR capabilities of Euclid’s Quick Data Release (Q1), I performed spectral energy distribution (SED) fitting to simultaneously constrain the properties of AGN and their hosts. Moreover, I present a new method to assess and improve the reliability of the measurements, based on simulated SEDs built from combined quasar and galaxy observations. I quantify how AGN emission impacts physical property estimations and demonstrate that SED fitting serves as a powerful diagnostic for AGN identification, achieving 85% purity and completeness. Furthermore, a comparative analysis of AGN selected via different methods reveals that these techniques probe partially distinct populations, highlighting the importance of multi-wavelength, multi-method approaches to mitigate selection biases in studies of galaxy evolution. Finally, we investigate the X-ray to mid-infrared luminosity relation and the evolution of the stellar mass–bolometric luminosity correlation across cosmic time. These results validate the utility of Euclid for constructing large, homogeneous AGN samples, providing a crucial foundation for mapping the co-evolution of supermassive black holes and their hosts over a wide range of redshifts. I will conclude my talk by showcasing how the community can leverage this catalogue for future AGN studies.

21.10.2026

Jan Benacek

Mgnetospheres of neutron stars