(Click on the title of each talk to see the abstract)

Monday

14:00	Registration
14:20	LOC	Introduction
	Chair: Felix Fuerst	Super-Eddington Accretion Physics
14:30	Yan-Fei Jiang	Super-Eddington Accretion Disks and Their Spectrum and Variability Properties I will describe our series of recent 3D global radiation MHD simulations of accretion disks onto stellar mass and supermassive black holes when the accretion rate exceeds the Eddington limit. These simulations span a wide radial range and encompass a variety of accretion rates. Near the inner region around the black hole, I will discuss how the interplay between turbulence due to magneto-rotation instability and radiation transport determines the properties of the disk. For the outer part of the disk, I will describe a thermally stable disk structure that can explain many spectrum properties of the UV/Optical emission from AGNs.
15:00	Luis Abalo	Super-Eddington Accretion in the Pulsating ULX NGC 7793 P13: Fourteen Years of XMM-Newton and NuSTAR Observations Pulsating ultraluminous X-ray (PULX) sources provide a framework to study super-Eddington accretion onto magnetised neutron stars. We present a uniform analysis of fourteen years of pointed XMM-Newton and NuSTAR observations of NGC 7793 P13, complemented by Swift monitoring. The spectra are modelled with two thermal components and one cut-off power law. At high luminosities (~10^40 erg s^-1), the source follows a luminosity-temperature relation consistent with constant temperature rather than T^4 scaling expected for a standard Shakura-Sunyaev thin disc. During a two-year off-state, when the total luminosity decreases by two orders of magnitude and pulsations are not detected, the hotter thermal component shows no significant temperature evolution, while the cooler component systematically decreases. Timing analysis confirms persistent spin-up throughout the campaign. Although the cut-off power-law component is expected to trace the pulsed emission, the pulsed fraction shows no correlation with its flux fraction. Instead, beyond the known anti-correlation with total flux, the pulsed fraction is anti-correlated with the flux of all model components, indicating that the pulsations are not confined to the cut-off power-law emission. Together, these results seem to indicate that the off-state variability is driven primarily by changes in the structure and viewing angle of the super-Eddington accretion flow, rather than by intrinsic variations in the mass accretion rate.
15:15	Tommaso Zana	Early Black Hole Growth via Super-Eddington Accretion: insights from High-Resolution Simulations Super-Eddington accretion may be crucial for explaining the existence of exceptionally massive black holes (BHs), exceeding 10^9 solar masses, observed as Active Galactic Nuclei at high redshifts (z∼6−7). Recent James Webb Space Telescope (JWST) observations strongly support the idea that early BHs grew significantly above the Eddington limit. Concurrently, numerical models are increasingly focusing on understanding the conditions, viability, and limitations of this extreme accretion process. In this context, I have conducted a detailed investigation into the impact of super-Eddington accretion on various BH seed masses within the typical gas-rich proto-galaxy environments at high redshifts (z∼15). I will present results from a state-of-the-art suite of high-resolution smoothed-particle hydrodynamical simulations. These simulations incorporate key physics, including star formation, photoionization, non-equilibrium cooling of primordial species, and a feedback prescription based on the slim disc model. I specifically tested the effects of both seed mass and feedback intensity on the BH growth process. I will demonstrate that, for gas-rich galaxies, even when isolated (i.e., without external interactions), neither star formation nor feedback processes can significantly limit the growth of black hole seeds, regardless of their initial mass. Super-Eddington accretion rapidly leads to the formation of very massive BHs (∼10^5 Msun) in just a few thousand years, making them overmassive with respect to their host galaxy, in agreement with JWST observations. Furthermore, I will show that through brief, super-Eddington bursts with small duty cycles, BHs can reach the observed masses by redshifts z∼6−7.
15:30	Luca Ighina	RACSJ0320-35: A Laboratory for Super-Eddington Accretion at z = 6.1 Super-Eddington accretion is thought to be a key ingredient in the early growth of the first supermassive black holes (SMBHs). While it has been widely invoked to explain the large black hole masses observed in bright high-z quasars, as well as the peculiar properties of many JWST detected AGN, direct observational evidence for such rapid accretion in the early Universe remains scarce. In this talk, I will present a comprehensive multi-wavelength study of RACS J0320−35, a radio-powerful quasar at z = 6.1. Dedicated Chandra observations reveal an unusually strong and soft X-ray spectrum, with a luminosity of LX=1.8e46 erg/s and a steep photon index of Γ=3.3±0.4, making it one of the most X-ray luminous quasars currently known at z>5.5. By analysing the SED, we show that both the distinctive X-ray spectral properties and the rest-frame UV emission are fully consistent with theoretical models of super-Eddington accretion. Owing to its exceptional luminosity across the electromagnetic spectrum, RACS J0320−35 provides a rare and valuable laboratory for directly testing models of rapid black hole growth in the early Universe.
15:45	Giacomo Fedrigo	Magnetised accretion on massive black hole binaries with general relativistic simulations An impelling problem in astrophysics is the characterization of the evolution processes of massive black holes (MBHs) and their surrounding environment. One of the main processes driving MBHs' growth is gas accretion on the event horizon. This problem naturally extends to the case of massive black hole binaries (MBHBs), where the accretion process is affected by the dynamic space-time. In this context, understanding the evolution of the circumbinary disc and the mechanisms governing gas transport toward the binary is of fundamental importance, as these processes regulate both the accretion history and the orbital evolution of the system. In addition, in the LISA era, MBHBs will be key multimessenger sources, thanks to the emission of strong gravitational wave (GW) signals. With this goal in mind, I will present a set of three-dimensional numerical simulations of compact binaries in the GW-driven phase, employing a recently implemented general relativistic magnetohydrodynamics module within a meshless scheme. This method enables us to study the characteristics of relaxed circumbinary discs without the constraint of an underlying fixed computational grid, while consistently accounting for magnetic and general relativistic effects. Hence, the scheme shows great computational efficiency and accuracy, allowing us to explore different binary-disc setups. I will focus on the analysis of the disc morphology and on the gas accretion processes in the super-Eddington regime, searching for characteristic signatures that may help identify binary systems embedded in AGN systems. Finally, I will present light curves and spectra obtained through post-processing ray-tracing techniques.
16:00	Galina Lipunova	Is it really a shock? Subsonic super-Eddington accretion onto magnetized neutron stars. For rapidly accreting magnetized NSs, the magnetically controlled funnel flows develop a radiation-mediated shock located above the NS surface. Most of the observed radiation is released below the shock, in the accretion column. The height of the accretion column is regulated by its radiative cooling and grows with increasing accretion rate. For sufficiently high accretion rates, the predicted shock location lies beyond the magnetospheric radius. We therefore propose a new regime of magnetospheric accretion, in which the flow remains subsonic throughout the magnetosphere. We show that such a regime can be realized for stars accreting at highly super-Eddington rates with relatively weak magnetic fields, B∼1e11 G, which also ensures the validity of the Thomson approximation for electron-scattering opacity. We develop an analytical model for the flow and verify the analytic results with one-dimensional time-dependent simulations. In our solution, radiation pressure within the flow is comparable to the magnetic pressure in the magnetosphere, enabling lateral mass leakage from the funnel walls and formation of a mildly relativistic outflow from within the magnetosphere. Such objects are expected to have super-Eddington accretion discs, while their X-ray pulsations are suppressed due to visibility effects and scattering in the outflows produced both by the disc and the magnetosphere. We therefore propose that the majority of observationally non-pulsating ULXs containing magnetized NSs accrete in this subsonic regime, whereas the comparatively rare pulsating ULXs host NSs with the strongest magnetic fields (surface B >~ 1e13 G), allowing a radiation-mediated shock to form.
16:15	Coffee break
	Chair: Haojie Hu	Super-Eddington Accretion Physics
16:45	Ari Laor	On the gas confinement by high L/L_Edd accretion disks - I In stars both gravity and radiation are spherically symmetric, and radiation pressure dominates gravity when L>L_Edd. In accretion disks the radiation pressure varies with height and distance, which leads to an “Eddington Surface”, above which the total force is directed outwards. This surface appears at L=0.5L_Edd, and moves downwards as L increases. At L ~0.8L_Edd the Eddington surface touches the inner accretion disk surface, and the disk gas is no longer confined. The disk de-confinement starts at larger radii with increasing L/L_Edd. This calls into question the ability of accretion disks to confine the very high accretion rate of the slim disk solution, as a significant fraction of the infalling gas can flow freely out of the disk. We present the numerical results of a study of the gas velocity field, and the implications on various disk properties.
17:00	Alexander Chemel	On the gas confinement by high L/L_Edd accretion disks – II The accretion disk surface is set by equating the local radiation pressure with the vertical component of the black hole gravity. Coronal gas resides above the accretion disk surface, and can be confined by the black hole gravity. As L approaches L_Edd, the Eddington surface moves down and the coronal confinement volume decreases. We study the potential effect of radiation pressure and radiative viscosity on the coronal gas flow and the coronal properties.
17:15	Pavel Abolmasov	The impact of corrugation shock front instability on the accretion column dynamics Super-Eddington magnetospheric accretion onto a neutron star is associated with the formation of a shock wave and an optically thick radiation-pressure-supported flow downstream of the shock, known as accretion column. Numerical simulations of such a flow show different modes of rapid (on the local dynamic time scales) variability interpreted as pressure modes, non-linear regime of the photon-bubble instability, or heating/cooling relaxation cycles. Here, I show that at least some of the variability patterns found in simulations may be explained by the corrugation instability of slow magnetosonic shock waves. I derive an analytic expression for the shape of the shock front, confirm its validity with two-dimensional numerical simulations, and discuss the observational implications of the effect.
17:30	Pu Du	Reverberation Mapping of Mg II Emission Lines in Super-Eddington Active Galactic Nuclei Super-Eddington active galactic nuclei (AGN) exhibit distinctive characteristics in their broad-line regions (BLRs) that diverge from those of sub-Eddington counterparts. Reverberation mapping (RM) has shown shortened Hβ time lags in super-Eddington AGNs, but systematic RM studies of the Mg II line have been lacking. We carried out an RM campaign from 2017 to 2024 on a sample of super-Eddington AGNs and successfully measured time lags for eight objects. We find that, like Hβ, their Mg II time lags are shorter than those in AGNs with normal accretion rates at comparable luminosities. Here we will report the results of this campaign and discuss their implications for BLR structure in extreme accretion regimes.
17:45	Fatemeh Kayanikhoo	Simulations of accretion onto compact stars as ULXs: the impact of compactness Neutron stars undergoing super-Eddington accretion are recognized as sources of ultraluminous X-rays. The radiative efficiency and accretion geometry of these systems are governed by several parameters, including the stellar magnetic field, the accretion rate, and the compactness of the central object. In this study, we present results from numerical simulations of accretion onto a magnetized compact star with varying compactness and surface magnetic field strength. We find that accretion onto a more compact star leads to higher radiative efficiency and stronger beaming of the emitted radiation. As a result, more compact stars are more likely to appear as ultraluminous X-ray sources (ULXs).
18:00	Mitch Begelman (remote)	Review talk Review talk
18:30	End of day

Tuesday

	Chair: Pavel Abelmasov	Super-Eddington Accretion Physics
9:00	Haojie Hu	Clumpy Outflows from Super-Eddington Accreting Black Holes: Radiation Hydrodynamics Simulations and Observational Implications Recent advances in X-ray spectroscopic observation have enabled discovery of distinct clumpy structures in the super-Eddington outflows from the supermassive black hole in PDS 456 (XRISM Collaboration 2025), initiating detailed investigation of fine-scale structures in accretion-driven outflows. In this talk, I will present our high-resolution, two-dimensional radiation-hydrodynamics (2D RHD) simulations with time-varying and anisotropic initial and boundary conditions to reproduce outflows launched from super-Eddington accretion flows and analyze their statistical properties. The resulting clumpy outflows extend across a wide range of radial distances and polar angles, exhibiting typical properties such as a size of ~10 rg (where rg is the gravitational radius), a velocity of ~0.05–0.2 c (where c is the speed of light), and about five clumps along the line of sight. Although the velocities are slightly smaller, these characteristics reasonably resemble those obtained from the XRISM observation. The gas density of the clumps is on the order of 10^−13–10^−12 g/cm^3, and their optical depth for electron scattering is approximately 1–10. The clumpy winds accelerated by radiation force are considered to originate from the region within <~300 rg. We will also discuss the possible formation mechanisms of clumpy outflows in super-Eddington accretion flows.
9:15	Discussion (Pavel Abelmasov)
	Chair: Alessandro Lupi	Black hole growth and galaxy evolution
9:45	Satoshi Yamada	Huge impact of quasar-mode feedback from accretion disk to cluster-core scales XRISM reveals UFO forests in super-Eddington quasars (e.g., PDS 456). Here, we report a new UFO forest in the late-stage merger IRAS 05189+2524, whose kinetic power is comparable to the Eddington (or bolometric) luminosity. This supports a scenario in which strong feedback can quench host-galaxy activity (Noda, Yamada+25, ApJL). The system shows two unique features: (1) rapid variability of the UFO forest due to a smaller SMBH mass, and (2) slower UFO velocities during the brighter phase, inconsistent with radiation-driven winds suggested in, e.g., PDS 456. This may indicate alternative driving mechanisms, such as MHD-driven winds. Our team has found supporting evidence for MHD-driven winds in lower-Eddington AGNs, NGC 3783 and NGC 4051 (e.g., Reeves+, submitted), both showing rapid UFO acceleration. We also study AGNs across a wide Eddington-ratio range (~10^-5 to 1), providing new insights into AGN feedback from the accretion disk (e.g., Yamada+, in prep.). Our new XRISM observations of quasar-hosting clusters reveal strong feedback (~1–10% of L_qso) on cluster-core scales, consistent with the latest cosmological simulations. Finally, we discuss AGN feedback from the accretion disk out to cluster-core scales (~100 kpc; e.g., Yamada+26, Nature Astronomy, submitted).
10:00	Giada Quadri	Super-Eddington accretion in high-redshift quasar hosts The James Webb Space Telescope is revolutionising our view of the early Universe, revealing bright, massive galaxies at redshifts z ≳ 10, together with puzzling sources called “little red dots” (LRDs). Both their origin and what powers these objects are still debated, but they may be linked to the formation and rapid early growth of the first massive black holes, possibly through phases of super-Eddington accretion. In this talk, I will present results from a state-of-the-art zoom-in cosmological simulation of a quasar progenitor, aimed at exploring whether such systems can shed light on the peculiar populations observed by JWST. I will discuss how black hole growth driven by super-Eddington accretion and feedback can lead to short-lived phases with a significant impact on the galaxy’s evolution, potentially quenching it. Moreover, throughout the evolution of the quasar host progenitor, the spectral properties of the system can resemble both LRDs and quenched galaxies, depending on the evolutionary phase considered. These results suggest that both LRDs and quenched galaxies could be transient stages in the life cycle of high-redshift galaxies.
10:15	Riccardo Caleno	The role of major mergers in triggering super-Eddington accretion JWST observations have opened a new window on the early Universe, revealing black holes with masses of several million solar masses already at z>8, which challenge our understanding of their accretion mechanisms. In recent years, super-Eddington accretion has emerged as a promising solution and has been adopted in both simulations and semi-analytical models. In this talk, I will present the results of my recent work investigating the role of super-Eddington accretion in cosmological hydrodynamical zoom-in simulations during a major merger between two haloes at z=11. We performed a suite of runs exploring different seeding prescriptions and feedback configurations. I will show that in the majority of the runs performed, the merger has a negligible impact on black hole accretion, while accretion is primarily regulated by black hole kinetic feedback and the gas density around it.
10:30	Coffee break
	Chair: Tommaso Zana	Black hole growth and galaxy evolution
11:00	Caroline Bertemes	Feeding the beast: Rapid accretion in an extremely red quasar at the core of a z=3 protocluster Super-Eddington accretion episodes are thought to play a pivotal role in black hole growth and in galaxy evolution, given the enormous energy output they generate. Extremely red quasars (ERQs) at high redshift constitute prime candidates for Super-Eddington accretion due to their exceptional luminosities (exceeding 10^47 erg/s) and inferred black hole masses of around a billion solar masses. Their intense outflows, reaching several thousand km/s in the warm ionised phase, suggest that they are caught in a short-lived transitional phase as they clear out central gas and dust. However, the mechanisms triggering their rapid growth in the first place are still an active topic of research. In this talk, I will present new JWST and ALMA observations of one of the most powerful ERQs at redshift 3, residing at the epoch of peak quasar activity. Resolved JWST/NIRSpec spectroscopy confirms the fast accretion flow while offering new constraints on the black hole mass, extended outflow properties and physical conditions of the interstellar medium. Deep slitless spectra from JWST/NIRISS reveal that the quasar resides at the core of a highly overdense and maturing protocluster with merger activity, which may have contributed to triggering its rapid growth. We identify additional AGN candidates, indicating an enhanced AGN fraction compared to the field. I will also show early results from an ongoing ALMA follow-up program, offering a first look into the resolved molecular gas properties of the central quasar.
11:15	Alessandro Lupi	Super-Eddington accretion and feedback in high-redshift quasar hosts: the impact of the black hole spin evolution For more than a decade, observations of high redshift quasars up to z~7 have told us that massive black holes (MBHs) were already in place, with masses well above 10^9 solar masses, when the Universe was less than 1 Gyr old. Recent observations by JWST have shown that MBHs are ubiquitous above z=6, even in lower mass galaxies, and are typically overmassive compared to their galaxy host. These results significant challenged to our understanding of how these objects formed and evolved, in particular when we consider that the energy produced by the accretion process is released into the MBH surroundings, producing outflows that can potentially interact with the interstellar medium, regulating/quenching star formation, but also inhibiting further MBH accretion. Despite decades of research, an accurate description of the processes at play is still missing, because of the huge dynamic range and the approximate modelling in current simulations. In particular, current studies suggest that, either i) the MBHs are already extremely massive at formation (M>10^5 Msun), or ii) they have to bypass an initially stunted growth (due to the strong impact of supernovae in the galaxy nucleus which significantly perturbs the inflowing gas). An appealing way to overcome this issue is represented by relatively short phases of accretion above the Eddington limit. In my talk, I will present a recent effort at modelling in the most accurate way possible the evolution of MBHs in high-redshift quasars, including super-Eddington accretion and the associated feedback. Despite the improvements of the last few years, cosmological simulations still employ very simple prescriptions to estimate the black hole accretion rate and the associated feedback, and mostly lack a proper description of the black hole spin, which is crucial in setting the feedback strength during super-Eddington accretion phases. In my talk, I will show how to overcome these limitations by means of super-Lagrangian refinement, which allow us to resolve the MBH influence radius and directly measure the mass flux onto the MBH, and through a consistent description of the spin evolution across different accretion regimes.
11:30	Filippo Barbani	BlackHoleWeather – Chaotic cold accretion across the meso-scale Supermassive black holes (SMBHs) play a central role in galaxy evolution, yet the physical mechanisms that feed them remain poorly understood. In realistic galactic environments, turbulence and radiative cooling can disrupt the equilibrium of hot halos, leading to the condensation of cold gas and the onset of chaotic cold accretion (CCA). Using high-resolution (0.1 parsec) 3D simulations with the GPU-native code AthenaPK, we study how turbulence shapes the formation and dynamics of multiphase gas at the meso scale in stratified group-scale halos. Our simulations reveal that strong turbulence promotes widespread condensation, producing clumpy cold clouds that collide and lose angular momentum, driving rapid and highly variable accretion onto the black hole—often exceeding classical Bondi predictions by several orders of magnitude. We also find that turbulence maintains a dynamically active multiphase medium, where cold, warm, and hot gas coexist. These results establish turbulence as the key physical link between the thermodynamics of galactic halos and the stochastic fueling of supermassive black holes.
11:45	Alessandro Trinca	Seeking the rise of Massive Black Holes with JWST: evidence for early super-Eddington growth The advent of JWST has revolutionized our understanding of the high-redshift Universe, enabling the exploration of Active Galactic Nuclei (AGNs) in unprecedented detail and extending observations to fainter and more distant objects. Early campaigns have revealed a ubiquitous population of AGNs at z>5. Many of these AGNs are powered by black holes (BHs) that appear significantly overmassive relative to their host galaxies when compared to local scaling relations, and they often display peculiar observational features, such as extreme X-ray weakness. Together, these findings pose a significant challenge to current theoretical models of early galaxy evolution. Exploiting the synergy between cosmological and high-resolution hydrodynamical simulations has been essential to investigate the formation pathways of this emerging population of massive BHs and follow their growth across different accretion regimes. Increasing evidence suggests that their early evolution may be dominated by short, highly efficient episodes of super-Eddington accretion onto the first BH ‘seeds’, likely favored by the extreme environments in the first galaxies. Such phases not only accelerate mass build-up but also substantially modify the structure of the accretion flow. We show how, under these conditions, the geometrically thick disk characterizing super-Eddington regimes may induce a strong bias in BH mass estimates, alleviating the apparent overmassiveness inferred from current observations. At the same time, strong Compton cooling of the coronal plasma within the funnel-like disk structure is expected to produce extremely soft X-ray spectra, naturally accounting for the lack of X-ray detections. Overall, this framework provides a coherent interpretation of the distinctive properties of high-redshift AGNs discovered by JWST, offering a pathway to reconcile them with the local population at later cosmic epochs.
12:00	Francesco Ziparo	A Selection Aware View of Black Hole–Galaxy Coevolution at High Redshift The rapid assembly of massive black holes (BHs) in the early Universe is often interpreted as evidence for widespread super-Eddington accretion. However, determining whether such extreme growth is required for the general population, or only for rare systems, remains an open question. Using the James Webb Space Telescope (JWST) Advanced Deep Extragalactic Survey (JADES) at redshift z ≳ 4, we infer the intrinsic BH–stellar mass relation for broad-line active galactic nuclei (AGN) with a forward-modeling Bayesian framework that explicitly accounts for broad Hα detectability and selection effects. I will show that the average relation between BH mass and host stellar mass is already consistent with the local scaling by redshift ~4–6. In other words, typical galaxies and BHs appear to grow in step even in the first billion years of cosmic history. In contrast, the intrinsic scatter is much larger than in the nearby Universe, indicating a wide diversity of growth histories. I will discuss how this combination, an established mean relation but large dispersion, naturally points to intermittent and heterogeneous accretion. In this picture, sustained super-Eddington growth is not required for the bulk of the BH population, but is instead confined to specific phases or rare systems that populate the upper envelope of the distribution. Finally, I will outline how future JWST samples can test whether these extreme accretion episodes are transient events or a defining feature of early BH formation.
12:15	Discussion (Alessandro Lupi)
12:45	Lunch break
	Chair: Francesco Tombesi	Active Galactic Nuclei and quasars
14:30	Alessia Tortosa	Review talk Review talk
15:00	Ciro Pinto	Ultra-fast outflows from highly-accreting supermassive black holes Deep surveys have revealed fully-grown supermassive black holes (SMBHs) powering active galactic nuclei at very high redshifts, when the Universe was a few hundred Myr old, less than 10% of its current age. This challenges the theories of black holes growth, requiring long periods of high accretion, most likely above the Eddington limit, where powerful outflows are expected to be launched by radiation pressure. These objects will be difficult to study in detail, even with future advanced observatories. However, in the nearby Universe, there are several objects that shine beyond Eddington, can be studied in great detail and used as proxy for early SMBHs such as Narrow line Seyfert 1 galaxies and tidal disruption events. A common denominator to these is the presence of extreme winds predicted by theoretical models of super-Eddington accretion. Among them the most extreme are ultra-fast outflows (UFOs), with mildly relativistic speeds and high ionisation states, one of the most promising candidates to drive AGN feedback. However, there are still several open questions on UFOs by far: 1) What is the mechanism accelerating winds up to relativistic speeds? 2) Do they affect the overall accretion process and SMBH growth? 3) Are UFOs powerful enough to drive AGN feedback? I will review the state-of-art progress in these questions, present our recent results from high-resolution X-ray spectroscopy, and show how new missions, such as XRISM and NewATHENA, will revolutionize the field through ad-hoc simulations.
15:15	Neeraj Kumari	A Broadband SpectralStudy of a Sample of Narrow-line Seyfert 1 Galaxies We present a broadband X-ray study of the coronal properties of a sample of Narrow-Line Seyfert 1 (NLS1) galaxies, systems widely regarded as laboratories for high and super-Eddington accretion. Using multi-epoch archival observations from XMM-Newton, Swift, and NuSTAR, we investigate the physical conditions of the X-ray–emitting corona in sources spanning a broad range in redshift (0.002 < z < 0.965), black hole mass (6 < log (M/M⊙) < 9), and bolometric luminosity (39.5 < log L₍bol₎ < 45.5). The X-ray spectra were modeled with a combination of a thermal blackbody component, ionized local absorbers, and a relativistic reflection model incorporating a cutoff power-law continuum. Well-constrained coronal temperatures and high-energy cutoffs were obtained for approximately 47% of the observations, while lower limits were derived for the remaining cases. The sample exhibits mean coronal temperatures of ∼107 keV and cutoff energies of ∼230 keV, with an average photon index (Γ)≈ 2.13 and optical depth (τ) ≈ 1.72. We find a mildly positive but weak correlation between Γ and the Eddington ratio (Pearson’s r = 0.37, p < 10⁻⁵), consistent with enhanced Compton cooling in high-accretion-rate flows expected in super-Eddington regimes, although significant scatter suggests additional regulating mechanisms. The compactness–temperature diagram shows that most sources lie well below the pair-production limit, clustering near the "sweet spot", indicating that Compton cooling dominates the coronal energy balance and that the plasma is largely pair-regulated even at high accretion rates. Finally, the weak anti-correlation between the soft excess and the hard X-ray Compton hump disfavours a blurred relativistic reflection origin for the soft excess, suggesting alternative emission mechanisms in NLS1s accreting near or above the Eddington limit.
15:30	Vieri Cammelli	AGN feedback-regulated simulations across the meso-scale Many key aspects of how Active Galactic Nuclei (AGN) feedback, powered by supermassive black holes, shapes the circumgalactic and intracluster media of galaxy groups and clusters remain uncertain. Likewise, the back-reaction of accretion flows and the formation of clumpy cold gas triggered by feedback are poorly understood. The BlackHoleWeather (BHW) project aims to address all major outstanding questions across the full range of relevant scales, to build a unified, self-consistent, and bottom-up description of AGNs. We are developing state-of-the-art models of black hole spin, feedback, turbulence driving, and chemical evolution. Via the GPU-accelerated AthenaPK code, we gain in resolution and physical fidelity, by resolving magnetic fields, powerful jets, and multiphase cold gas at unprecedented detail. The outcome will be a comprehensive picture of black hole feedback that connects processes across scales and phases, testing theoretical predictions and guiding future observations.
15:45	Giacomo Venturi	The first spatially resolved study of feeding and feedback in local super-Eddington AGN Super-Eddington (SE) AGN are invoked to explain the early growth and properties of SMBHs at high redshift. Nonetheless, SE AGN are so far poorly understood in terms of their feeding and feedback mechanisms. Local SE sources constitute a unique opportunity to probe this accretion regime in detail, by connecting the properties of the central engine with those of the gas on galaxy scales. I will present our program targeting a sample of extreme local SE AGN with VLT/MUSE optical IFU spectroscopy to map the properties of the ionised gas in the host galaxy and circum-nuclear regions, complemented with ALMA and NOEMA sub-mm data for the cold molecular gas (and soon by JWST MIRI and NIRSpec IFU observations for warm molecular + highly ionised gas and PAH). We characterise galactic outflows (velocity, mass rate) and connect their energetics with that of AGN radiation and nuclear X-ray winds. Preliminary results indicate that outflows have limited spatial extension, consistent with being in their initial blow-out phase after the SE episode activation. The combination of low- and high-spatial resolution MUSE and ALMA data spanning from galactic down to nuclear scales allows us to also probe whether SE accretion is primarily sustained by mergers funnelling gas towards the nucleus or to secular galactic bar-driven inflows. This campaign will provide the first detailed multi-phase, multi-scale study of feeding and feedback in local SE AGN and constitute a critical benchmark for high-redshift studies.
16:00	Coffee break
	Chair: Pierpaolo Condò	Active Galactic Nuclei and quasars
16:30	Riki Sato	Probing the Geometry of Lower-Ionized Ultra-Fast Outflows in the High-Eddington-Ratio Quasar PDS 456 with XRISM and NuSTAR Ultra-fast outflows (UFOs), ejected from accretion disks at velocities of 0.03–0.3 c, are a key ingredient in disk-wind physics in high-Eddington-ratio accretion systems. In such extreme accretion regimes, the acceleration mechanism of UFOs—whether radiation-driven or magnetohydrodynamic (MHD)–driven—remains poorly understood. To distinguish between these mechanisms, it is crucial to uncover the geometry of UFOs. We focused on PDS 456 (Eddington ratio〜1), a unique active galactic nucleus in which UFOs are consistently and significantly detected. We observed PDS 456 with XRISM and NuSTAR in March 2024, which provided broadband X-ray spectral coverage from 0.4 to 20 keV, and valuable variability information from 500 ks of long-term data. We discovered that the spectrum is heavily absorbed in the soft X-ray band (0.5−5 keV), and this feature is well explained by a lower-ionized (ξ=10^3) UFO. This lower-ionized UFO appears as partially covered absorption and has an outflow velocity of 0.3c. Furthermore, we observed that the covering factor of this lower-ionized UFO varied by approximately 5% over the 500 ks observation. This variability can be interpreted as the absorber crossing our line of sight. Based on this interpretation, we estimated the crossing velocity across the line of sight as 1500 km/s. By applying the conservation of angular momentum between the launching point and the observation point, we concluded that the distance of the lower-ionized UFO from the black hole exceeds 3000 Rg, where Rg is the gravitational radius. This leads to a new understanding of the UFO's geometry: the lower-ionized UFO is located outside the higher-ionized UFO (ξ=10^5) at 200–600 Rg, and both components have the same outflow velocity of 0.3 c. This newly revealed geometry provides direct insights into the acceleration mechanism of UFOs. A nearly constant velocity over increasing distance favors a radiation-pressure-driven origin.
16:45	Andrea Sacchi	Are Little Red Dots Powered by Highly Accreting Supermassive Balck Holes? Little red dots (LRDs), high-redshift, red, and compact galaxies, are one of the most puzzling discoveries by JWST. The emission of these galaxies has been argued to be powered by accreting 1e7~1e8 Msun supermassive black holes (SMBHs). This claim has crucial consequences for our understanding of how the first black holes form and grow over cosmic time. A key feature of LRDs is their extreme X-ray weakness: analyses of individual and stacked sources have yielded non-detections or only tentative, inconclusive X-ray signals, except for a handful of individual cases. As the most natural explanation, i.e., high obscuration, seemed disfavored by JWST spectroscopic evidence, several authors have suggested that the X-ray weakness of LRDs is intrinsic, due to super-Eddington accretion rates. In my talk, I will show how by stacking X-ray data for 55 LRDs in the Chandra Deep Field South (accumulating a total exposure time of nearly 400 ∼Ms) we can, for the first time, test these models. Our results rule out current super-Eddington accretion models and are compatible only with extremely high levels of obscuration. I will present possible ways to reconcile our observation constraints with our current understanding of accretion and high-redshift SMBHs.
17:00	Sakiko Obuchi	Discovery of an X-ray Luminous Radio-Loud Quasar at z = 3.4: A Possible Transitional Super-Eddington Phase How supermassive black holes (SMBHs) acquired their mass remains one of the fundamental open questions. Recent JWST discoveries have pushed the redshift of active galactic nuclei (AGN) up to z ≈ 11, further deepening the tension between observations and theoretical models of black hole seed formation. One possible solution is an accretion phase exceeding the classical Eddington limit, known as super-Eddington phase. In such environments, the central SMBHs are often heavily obscured by abundant gas and dust, highlighting the importance of multi-wavelength AGN surveys. X-ray and radio surveys are particularly powerful in this aspect, since both bands provide strong penetrating capabilities. We present multi-wavelength properties of eFEDS J084222.9+001000 (eFEDS ID830), a quasar at z = 3.4351, identified as the most X-ray luminous radio-loud quasar in the eFEDS field. ID830 shows a rest-frame 0.5–2 keV luminosity of L_0.5-2 keV = 10^46.20 erg/s, with a steep X-ray photon index (Γ = 2.43), and a radio counterpart detected with VLA/FIRST 1.4 GHz and VLASS 3 GHz bands. Subaru/MOIRCS J-band spectra also clearly detected MgII2800 emission, yielding the black hole mass of M_BH = (4.40±0.72)×10^8, and an Eddington ratio of λ_Edd = 1.44±0.24 from the UV continuum luminosity and λ_Edd = 12.8±3.9 from the X-ray luminosity, indicating super-Eddington accretion. This extreme X-ray luminosity results in a high α_OX = −1.20, larger than quasars and little red dots in super-Eddington phase with similar UV luminosities, typically showing α_OX < −1.8. We propose that ID830 may represent a transitional phase after an accretion burst, evolving from a super-Eddington to a sub-Eddington state, which could naturally describe its unusually high α_OX.
17:15	Misaki Mizumoto	Multi-Component Outflow in the Eddington-luminosity Source PG 1211+143 We present high-resolution X-ray spectroscopic observations of the UFO structure in the near-Eddington quasar PG 1211+143, utilizing the XRISM and XMM-Newton satellites. The XRISM/Resolve spectra clearly reveal a prominent P Cygni profile and resolve the Fe-K absorption into six distinct velocity components, ranging from v = -0.074c to -0.405c. Some UFO components exhibit narrow line widths of approximately sigma_v ~ 200 km/s, suggesting that the outflows have minimal velocity shear. The mass outflow rate is estimated to be ~1 solar mass per year, which is comparable to the Eddington accretion rate. In the XMM-Newton/RGS spectra, lower ionization counterparts of the Fe-K velocity zones are observed. These soft X-ray absorbers tend to be less ionized than their Fe-K counterparts, with opacity mainly arising from Fe-L shell lines and highly ionized oxygen. By comparing the Resolve and RGS absorbers, we demonstrate that the outflow can be parameterized with a density profile varying with radius as r^(-5/3), while the lower ionization zones likely originate from denser clumps of gas. Pure electron scattering appears insufficient to provide the thrust required to drive the wind, unless sufficient low-ionization gas capable of radiative line driving exists out of the line of sight. Overall, PG 1211+143 provides further evidence for the clumpy nature of accretion disk winds, consistent with recent XRISM findings for the quasar PDS 456.
17:30	Jaeden Bardati (remote)	Tracing the Spectral Properties of a Super-Eddington Quasar from Galactic to ISCO Scales Understanding quasar feedback requires models that connect galaxy-scale inflows to accretion-disk physics. I present spectral predictions from a radiation-magnetodynamics cosmological zoom-in simulation that follows a rapidly accreting, super-Eddington SMBH from galactic scales through a magnetically dominated disk down to the innermost stable circular orbit. I highlight three findings: 1) how galaxy-scale inflow and dust geometry shape the IR emission, 2) how intense host star formation contributes to the UV/optical-IR spectrum, and 3) how local gas conditions give rise to a broad-line region. Our z=4.4 system undergoes a starburst and an IR-bright early AGN phase resembling a hot dust-obscured galaxy, emphasizing how coupling super-Eddington disk physics to galaxy-scale environments is essential for interpreting the appearance and feedback of quasars.
17:45	Mateusz Rałowski	Studying the quasar - host co-evolution: the role of contaminations Quasars are the most luminous type of AGN and, as such, can be studied over long cosmic time, and treated as unique cosmic laboratories. However, the relation between the evolutionary phases of the AGN itself and its host galaxy is still far from clear. At the same time, the understanding of the co-evolution of AGN and its host galaxy will both improve modelling and classification of AGN, and help calibrate quasars for cosmological applications. In our recent spectral energy distribution analysis (Ralowski et al. 2026) focused on the optical - infrared (OPT-IR) wavelength range, based on a multi-wavelength photometric sample of almost 400 quasars, we studied the contamination from the host galaxies to the observed emission from central source of quasars from redshift z≈2.4 to z≈0.7. The OPT–IR luminosity relation originates from accretion disk and dusty torus emission. Observationally, however, it exhibits a significant scatter. Spectral energy distribution decomposition allowed us to identify major contaminants, particularly those arising from polar dust, the interstellar medium, and stellar emission, each affecting both optical and infrared. Different contaminants dominate at different redshift ranges, and differently affect Type I and Type II quasars. Although the AGN dominates the total emission from the source, host-galaxy contamination must be accounted for to achieve precise modeling of AGN central engines, and accurate calibration of quasar luminosities. Based on the above analysis in Ralowski et al. 2026, we try to use OPT-IR relation for cosmological test. Using the modified Risality & Lusso 2015 methodology we construct the Hubble diagram, and estimate cosmological parameters.
18:00	Discussion (Alessia Tortosa)
18:30	End of day

Wednesday

	Chair: Ciro Pinto	Active Galactic Nuclei and quasars
9:00	Jian-Min Wang	Review talk Review talk
9:30	Gabriele Matzeu	A newly discovered P-Cygni like profile in the quasar LBQS 1338-0038: powerful UFO or relativistically blurred reflection? We present a detailed XMM-Newton (XMM) and NuSTAR X-ray spectral analysis of the luminous Type I quasar LBQS 1338-0038 (LBQS hereafter) located at z=0.23745 with a bolometric luminosity of log(Lbol) ~ 46 ergs/s together with a black hole mass of log(MBH/M⊙)=7.77±0.03 indicates that LBQS 1338-0038 accretes almost at the Eddington limit . Such a high accretion rate is a prime ingredient for launching a ultra-fast outflow (UFO). From our optical/UV/X-ray SED modelling of the XMM and NuSTAR, we find that the rest energy of the centroid of the broad emission line is at Erest,em~6.6 kev with $\sigma\sim300\ev$ which is consistent with either Fe XXV-FeXXVI transitions or a blend of the two. The centroid energies of two absorption lines are found at Erest,abs1 ~ 8.00 kev and Erest,abs2 ~11 kev. Analyzing the XMM and NuSTAR data with physically motivated models, we detected a prominent P-Cygni like profile in the Fe K band consistent with a UFO with velocity vout ~ – 0.150c and ~2Ω covering factor. We also detected a faster UFO zone with vout ~ – 0.50c which might arise from a wind streamline located closer into the black hole. Such framework suggests the inhomogeneous a multi-phase nature of UFO already observed with XRISM/Resolve in PDS 456. We thoroughly investigated whether the P-Cygni profile of LBQS 0038-1338 arises from an different physical scenario such as the blurred relativistic reflection and whether we can differentiate between these two.
9:45	Bartolomeo Trefoloni	Cracking the quasar accretion puzzle: a thin disc and an intrinsically narrow Eddington ratio distribution are enough Quasars (QSO) efficiently turn gravitational energy into huge luminous outputs, as matter spirals towards a supermassive black hole (SMBH) through an accretion disc. The main properties of QSO spectral energy distributions (SEDs) are mainly governed by few parameters, namely the SMBH mass ($M_{\rm BH}$), the accretion rate ($\dot{M}$) and the efficiency (i.e. the SMBH spin). Despite the general agreement on these very general grounds, there is growing evidence for puzzling observational findings. In particular, the SEDs predicted by $M_{\rm BH}$ estimated via the single-epoch (SE) method often do not agree with observations. Furthermore, extremely tight correlations between broad lines and continuum luminosities (i.e. the Baldwin effect) still lack a compelling, unified explanation. In my talk, leveraging observations of some 100,000 QSOs, on a wide redshift range, I will show how these, and other inconsistencies can be naturally solved if blue optically-selected QSOs are powered by a classic geometrically thin and optically thick accretion disc with a narrow Eddington ratio distribution. Within this simple framework: 1) the slopes of the Baldwin effect are successfully predicted, 2) the continuum luminosity itself provides more accurate estimates of $M_{\rm BH}$ than SE prescriptions, 3) super-Eddington QSOs are extremely rare, posing tight constraints on the burstiness of the super-critical accretion phases.
10:00	Pierpaolo Condò	Unveiling AGN Wind Dynamics: From Real-Time Acceleration to Advanced Relativistic Modeling Ultra-fast outflows (UFOs) are critical drivers of AGN feedback, yet the mechanisms governing their launching and acceleration remain debated. IRAS 13224-3809, a highly variable Narrow-Line Seyfert 1 galaxy, provides an ideal laboratory for studying these processes at high accretion regimes. We present a systematic, time- and flux-resolved re-analysis of the 1.5 Ms XMM-Newton and 500 ks NuSTAR campaign from 2016, employing equal-count spectral selections. Our analysis unambiguously confirms a strong, variable UFO with velocities reaching ~0.38c. By tracking the wind’s evolution across consecutive time intervals, we report direct evidence of rapid wind acceleration (a~50 m/s²) in response to an X-ray flare. This prompt coupling between the radiation field and outflow velocity might favor magnetic driving mechanisms, over pure radiative acceleration. To complement these findings and meet the requirements of current and future high-resolution X-ray spectroscopy (e.g., XRISM, NewAthena), we also present updates to the Wind in the Ionized Nuclear Environment (WINE) code. The WINE framework has been substantially optimized for speed and resolution, incorporating full special-relativistic modeling of both absorption and emission within flexible biconical geometries. This enables robust constraints on wind parameters and precise estimates of mass and energy outflow rates, breaking degeneracies that have limited previous studies and providing the necessary modeling framework to interpret the high-resolution era of black hole winds.
10:15	Shu Wang	Tracer Dependent Hβ Radius–Luminosity Relation: Comparing Sub- and Super-Eddington AGNs We revisit the Hβ broad-line region (BLR) radius–luminosity (R–L) relation using a uniformly re-analyzed compilation of reverberation-mapped AGNs. Building on this homogenized set of Hβ lag measurements, we examine how the R–L relation depends on different luminosity tracers, including the optical continuum at 5100 Å (L5100), broad Hβ luminosity (L_Hβ), narrow [O III] luminosity (L[O III]), and hard X-ray luminosity (L_2–10 keV). We find that the scatter and slope depend on the adopted tracer. In particular, super-Eddington AGNs show systematic offsets relative to sub-Eddington AGNs in the R–L5100 and R–L_Hβ relations, while the two populations are broadly consistent in the R–L[O III] and R–L_2–10 keV relations. These results provide important clues to the origin of the systematically smaller BLR sizes in super-Eddington AGNs, and motivate models that can simultaneously explain the different deviation when using different luminsoity tracers.
10:30	Coffee break
	Chair: Giada Quadri	Active Galactic Nuclei and quasars
11:00	Kristina Kallova	Multi-wavelength view of local super-Eddington AGN Super-Eddington accretion in Active Galactic Nuclei (AGN) plays a key role in understanding rapid growth of supermassive black holes (SMBHs), particularly in the early Universe. The accretion disk properties, and the interplay between the accretion disk and X-ray corona are, however, still poorly understood, especially in the extreme SMBH growth regime. Multi-wavelength analysis via spectral energy distribution (SED) of rapidly accreting AGN in the local Universe can provide important constraints on changes in the accretion mode and the coupling between the accretion disk and X-ray corona. In my talk, I will present the results of broad-band SED analysis of a well-defined sample of super-Eddington accreting AGN in the local Universe, obtained by light decomposition between the AGN and host galaxy with the GALFITS. I use various disk models to fit the simultaneous optical-to-X-ray SEDs and I derive fundamental AGN properties such as the X-ray bolometric corrections and optical-to-X-ray spectral indices to compare with a sample of local sub-Eddington AGN matched in black hole mass.
11:15	Kazuki Fujikawa	Modeling X-Ray Spectra from Clumpy Ultra-Fast Outflows with Three-Dimensional Monte Carlo Radiative Transfer Calculations PDS 456 is an extraordinary quasar hosting a super-Eddington accreting Active Galactic Nucleus (AGN). Its extreme accretion activity and powerful relativistic winds make it an ideal object for investigating AGN feedback and the physical mechanisms of mass ejection from supermassive black holes. The X-ray observation satellite XRISM, launched in 2023, has an energy resolution approximately ten times higher than that of conventional satellites. XRISM observations of PDS 456 revealed a clumpy Ultra-Fast Outflow (UFO) structure composed of five distinct velocity components (XRISM Collaboration, 2025). However, conventional one-dimensional (1D) radiative transfer calculations cannot incorporate clumpy structures, making it impossible to accurately derive detailed geometric properties from the observational data. In this study, we calculated X-ray spectra from the clumpy UFO using the three-dimensional Monte Carlo radiative transfer code MONACO (Odaka et al., 2011). Based on XRISM-derived parameters, we placed 100,000 clumps with a diameter of 10 Rg (Rg is the gravitational radius), distributed within a hemispherical region spanning 400–600 Rg from the black hole, and assigned them bulk velocities in the range 0.226– 0.333c. As a result, our simulations successfully reproduce the observed five-component absorption-line structure, as well as the shape and intensity of the broad emission-line feature. To investigate the effects of clumpy structure, we compare the simulated X-ray spectra with those assuming a uniform outflow structure, modeled as a spherical shell with a homogeneous gas density, while matching the average hydrogen column density between the clumpy and uniform models. The results show that clumpy structures exhibit lower emission-line intensities than uniform structures. This reduction is attributed to smaller effective optical depth. In this presentation, we discuss the simulation results in detail and quantitatively evaluate the impact of clumpy structures on emission-line properties, together with a comparison to previous 1D calculations.
11:30	Keqin Zhao	Full-Band Modeling of photoionized AGN winds in NGC 3783 Ionized outflows are multiphase plasma streams extending from hundreds to thousands of parsecs from active galactic nuclei, representing a critical mechanism of galactic evolution. These complex gas flows, characterized by velocity ranges of 100-3000 km/s and diverse ionization states, play a crucial role in shaping galactic evolution and structure by removing or heating gas, starving galaxies of star-forming fuel. To comprehensively understand these dynamic phenomena, high-resolution X-ray spectroscopic observations have become crucial. NGC 3783, a nearby Seyfert 1 galaxy with rich spectral characteristics, serves as an ideal astronomical laboratory for studying ionized outflows. This galaxy has been extensively investigated across multiple wavelengths and harbors one of the most substantial warm absorbers ever observed. My work is based on a 10-day campaign conducted in 2024 on NGC 3783, representing an unprecedented and coordinated effort involving XRISM, XMM-Newton, and five additional space missions. The revolutionary spectral resolving power of XRISM, combined with XMM-Newton's RGS, is a game-changer in the study of ionized outflows. While warm absorbers are often considered quasi-steady, our observations reveal significant variability. Specifically, the column density of the intermediate ionized component, which primarily contributes to the Fe unresolved transition array at the L-shell, has increased by a factor of three over 24 years. This indicates that the system has undergone significant structural and dynamical evolution during this period.
11:45	Francesco Tombesi	Breaking the Wind Barrier: Super-Eddington Accretion and Relativistic Black Hole Winds Super- and Near-Eddington accretion onto supermassive black holes (SMBHs) is expected to launch powerful winds, yet their structure, acceleration, and variability remain poorly constrained. Ultra-fast outflows (UFOs), observed in X-rays at relativistic velocities, provide a direct probe of this extreme regime and its role in black hole growth and AGN feedback. In this talk, I will present recent progress in understanding SMBH winds in super- and near-Eddington systems, enabled by new high-resolution X-ray observations with XRISM/Resolve. These results reveal multiple discrete velocity components and a clumpy, multi-phase wind structure, inconsistent with simple steady-state models and pointing to complex, possibly time-dependent, acceleration mechanisms. The very high power inferred for these outflows also poses significant challenges for current AGN feedback models. These results open a new window on the physics of accretion and feedback when black holes operate beyond classical limits.
12:00	Discussion (Francesco Tombesi)
12:30	Lunch break
	Chair: Roberta Amato	X-ray binaries and ULXs
14:30	Alexandra Veledina	Review talk Review talk
15:00	Aman Upadhyay	Understanding the accretion geometry of M51 ULX-8 Ultraluminous X-ray sources (ULXs) provide a valuable laboratory for studying accretion under super-Eddington conditions. We present a combined timing and spectral analysis of M51 ULX-8 aimed at constraining its accretion geometry. Using multiple independent timing analysis techniques, we detect significant quasi-periodic oscillations (QPOs) at characteristic timescales of 20,894 s, 29,713 s, and 47,893 s, indicating variability in the accretion flow over a wide range of temporal scales. These long-timescale QPOs may be associated with geometric effects such as accretion disk precession expected in super-Eddington systems. We investigate the spectral evolution of the source across different luminosity states and find that the disk emission follows a luminosity–temperature relation consistent with 𝐿∝T2, supporting a slim disk accretion geometry in the system. The combined timing and spectral properties suggest a geometrically thick, radiatively inefficient accretion flow in M51 ULX-8, where variability is closely linked to changes in the accretion structure. These results provide new constraints on the accretion geometry of M51 ULX-8 and underscore the importance of joint timing–spectral analyses in understanding the physical mechanisms driving ULXs
15:15	Srimanta Banerjee	Super-Eddington Accretion in NGC 5055: X-ray Study of NGC 5055 X-1 and the ULX Population Ultraluminous X-ray sources (ULXs) provide key insights into super-Eddington accretion and its associated variability and feedback processes. The nearby spiral galaxy NGC 5055 (D= 9.04 Mpc) hosts a population of ULXs, including the luminous source NGC 5055 X-1, which reaches X-ray luminosities above 10^40 erg s⁻¹, making it an ideal target to study accretion across the ULX regime within a common environment. We present a comprehensive study of NGC 5055 X-1 and the galaxy’s full ULX population, combining a new deep XMM-Newton observation with all available archival X-ray data. This dataset enables a systematic characterization of the spectral properties, state behavior, and long-term variability of the ULXs in NGC 5055. The depth of the new observation also allows high-resolution RGS spectroscopy of NGC 5055 X-1 for the first time, providing a sensitive search for emission and absorption features associated with disk winds and outflows expected from super-Eddington accretion. In addition, several previously unstudied X-ray sources detected within the field of view are identified and analyzed. Therefore, our study provides the most complete view to date of the ULX population in NGC 5055 and offers new constraints on accretion physics, spectral variability, and feedback processes at extreme luminosities.
15:30	Felix Mirabel (remote)	Super-Eddington Acretion in GRS 1915+105 We compare Very Large Array observations of GRS 1915+105 made in 1994 and 2023, with nearly three decades of difference. The source has experienced intriguing major changes. The position angle of the bipolar ejecta in the plane of the sky has increased counterclockwise by 24°. The inclination angle of the flow with respect to the line of sight has increased by 17°. The observations of 2023 also show the temporal quasi-sinusoidal radio oscillations reported for several previous epochs. However, the 2023 oscillations are faster than ever before, with a period of about 8 minutes as opposed to the periods in the range of 20–40 minutes observed in previous epochs. Analysis of GRS 1915+105 images over the years suggests that the observed changes took place within a year or less. Our analysis indicates that during 2023, the plane of the accretion disk with an accretion rate enhanced by a factor of ∼4.3 was aligned with the line of sight, which may explain the deep X-ray obscured state and the high mid-infrared luminosity observed with JWST in that epoch. More recent 2024 observations show that the position angle of the ejecta has returned to its historic values. Future monitoring of the time evolution of the source may clarify the cause of these remarkable changes.
15:45	LOC	Gather for social trip
16:00	Social trip and dinner
23:00	End of day

Thursday

	Chair: Alexandra Veledina	X-ray binaries and ULXs
9:00	Varpu Ahlberg	The polarized signatures of super-Eddington accretion Certain Galactic X-ray sources, such as SS 433, have long been suspected to be concealed super-Eddington accreting objects. As their inner disk emission would only be visible via reflected and reprocessed radiation from the wind, their X-ray emission should be strongly polarized. The high degree of polarization observed in Cygnus X-3 was found consistent with this manner of obscuration. Notably, the polarized signature of concealed super-Eddington sources can encode information about the geometry and structure of their outflows. To explore how different outflow parameters impact the polarization, we conducted Monte Carlo radiative transfer simulations of the reflection. We found that the reflection only beams the emission when very little absorption was present; however, the strong polarization of Cygnus X-3 is only possible with significant absorption. We therefore concluded that if Cygnus X-3 is a beamed super-Eddington source, the outflow must have a complex ionization structure or the re-emission of absorbed radiation must be a significant factor. X-ray polarimetry is thus a new tool in exploring the physics behind beaming in super-Eddington sources.
9:15	Matteo Bachetti	Precise timing of the M82 ULXs - pulsations, QPOs, and more The M82 galaxy hosts two of the most famous ULXs: M82 X-1, a candidate IMBH, and M82 X-2, the first pulsating ULX. However, their 5" angular separation complicates their study with most X-ray missions. We present extensive timing and spectral timing studies of the two sources, overcoming the limitations of simple spectral studies. These observations provide, among others, an accurate measurement of the orbital evolution for X-2, a better spin up-luminosity relation for the same source, and a clear characterization of the QPO evolution in X-1, which appears reminiscent of known HMXBs. We will also detail a number of lessons learned that can help the characterization of other ULXs and high-luminosity sources.
9:30	Shogo Kobayashi	A first insight into an ultraluminous X-ray pulsar with XRISM: a high-resolution spectral analysis of M82 X-2 We present the first phase-resolved, high-resolution X-ray spectroscopic study of an ultraluminous X-ray pulsar (ULXP) using the XRISM satellite. During the performance verification phase, XRISM observed the starburst galaxy M82 for 207.7 ks, finding a hint of coherent X-ray pulsations from the ULXP M82 X-2 with a period of 1.387270 s, consistent with previous measurements. The Fe Kα line extracted from pulse-on phases exhibits a significantly broader width (~36 eV, with large uncertainties) than that seen during pulse-off phases. The line width corresponds to a velocity dispersion of order 1000 km/s, too large to be explained by thermal or turbulent motions in the companion star’s atmosphere. Phase-resolved spectroscopy shows that the Fe Kα line intensity and width vary coherently with the pulsation, demonstrating that at least part of the iron fluorescence originates from the ULXP system itself. Timing constraints from the pulse rise time place an upper limit of ~63000 km on the distance between the neutron star and the Fe line-emitting region, which is smaller than the neutron star’s Roche-lobe radius. This suggests an origin in the accretion flow, such as the inner accretion disk, rather than in extended diffuse gas. A narrower Fe K-alpha component detected during pulse-off phases is consistent with contamination from surrounding diffuse emission in M82. This study reports the first insight into the Fe K-alpha emission associated with an extragalactic ULXP accreting at luminosities exceeding ten times the Eddington limit, demonstrating the unique capability of XRISM to probe the inner accretion environment of super-Eddington neutron stars.
9:45	Dimitrios Konstantinos Maniadakis	Broadband pulsed fraction spectroscopy of Vela X-1: cross-calibration and modelling with simultaneous XMM-Newton and NuSTAR observations Pulse profiles provide a powerful diagnostic of the emission geometry and radiative processes in accreting X-ray pulsars, but their observed shape is affected by instrumental properties. We demonstrate that the energy-dependent pulsed fraction can be used as a robust timing cross-calibration diagnostic to combine XMM-Newton/EPIC-pn and NuSTAR observations. Using a simultaneous observation of the accreting pulsar Vela X-1, we show that once instrumental effects such as deadtime, energy redistribution, and source and background region selection are accounted for, the pulsed fraction measured by the two instruments can be consistently superimposed in their common energy range. This enables a seamless combination of XMM-Newton and NuSTAR data covering the 0.5–70 keV band. Residual differences around the iron-line region are attributed to the different energy resolutions of the instruments. Modelling the pulsed fraction obtained from the combined dataset reveals localized broad dips likely associated with cyclotron scattering features and narrow dips likely associated with soft X-ray emission lines. We further conduct an orbital phase–resolved Bayesian modelling of the pulsed fraction using the EPIC-pn data to evaluate how its timing signature changes with absorption, revealing that the timing signatures of emission lines become more pronounced when the corresponding spectral features are weak. This demonstrates that timing analysis is sensitive to scattering processes not always evident in energy spectra, highlighting its role as a powerful complement to spectroscopy.
10:00	Felix Fuerst	NGC 7793 P13 goes to the Upside Down NGC 7793 P13 is an outstanding ULX pulsar, exhibiting clearly detected pulsations with a period of approximately 415 ms. We have monitored its pulse period evolution over the past ~13 years using XMM-Newton and NuSTAR. During this time, P13 entered an off-state in which the X-ray flux dropped by more than two orders of magnitude. Remarkably, however, the spin-up of the source continued unabated, and P13 was spinning significantly faster after emerging from the off-state. The pulse profiles before and after the off-state are virtually identical, including their energy dependence. The pulsed fraction increases toward higher energies. In contrast, during the decline into the off-state, the pulsed fraction at the highest energies decreased substantially, while the low-energy pulsed fraction remained largely unchanged. This resulted in an inverse correlation between pulsed fraction and energy, effectively turning the usual energy dependence upside down. These observations suggest that the off-state is driven by a change, either intrinsic or geometric, in the innermost regions of the accretion flow where the highest-energy photons are produced and not by a cessation of accretion.
10:15	Francesco Barra	Evidence for ULX-like winds during the 2019 outburst of RX J0209.6−7427 Accretion onto compact objects naturally leads to the launch of disc winds. These outflows are observed in Galactic X-ray binaries and are often even more pronounced in extragalactic systems, especially ultraluminous X-ray sources (ULXs), which can exhibit powerful, relativistic winds. At larger distances, however, their detection remains limited, and the physical mechanisms that drive these winds are difficult to constrain in detail. In this context, RX J0209.6−7427 provides an exceptional nearby laboratory to investigate super-Eddington accretion and associated relativistic outflows. This transient ultraluminous X-ray pulsar in the Small Magellanic Cloud underwent an outburst in 2019, during which it exceeded the Eddington limit and reached a luminosity of 10^39 erg/s. Using XMM-Newton data, we characterised the plasma conditions during the outburst, detecting highly significant emission and absorption lines. We model these features by systematically exploring the velocity–temperature parameter space with state-of-the-art photoionisation and collisional-ionisation models. The results suggest a multiphase photoionised plasma composed of a rest-frame emitting gas and two blueshifted absorbing components with velocities of 0.1-0.2c. These components share properties with the outflows commonly observed in canonical extragalactic ULXs, despite differences in the characteristic timescales of the super-Eddington regime. We will compare these findings with those obtained for another extragalactic ULX, namely ESO 364-29, leveraging a deep, recent XMM-Newton observing campaign.
10:30	Coffee break
	Chair: Matteo Bachetti	X-ray binaries and ULXs
11:00	Hannah Earnshaw	The evolving broadband spectrum of NGC 4190 ULX-1 At a little under 3 Mpc distance, NGC 4190 ULX-1 is among our closest and most accessible ULXs to study. It is persistently observed at ULX luminosities, but also exhibits strong long-term variability in flux and spectral shape, particularly at high energies, as well as a particularly low-energy spectral break. We present the results of a recent sequence of XMM-Newton and NuSTAR observations, over which the source shows dramatic changes in its accretion disk component and its high-energy (>10 keV) tail, and place them in the context of Swift monitoring and archival datasets in order to determine the changing geometry of the system.
11:15	Jiahui Huang	How Do Super-Eddington Outflows Expand and Affect Their Environments? — Insights from 3D Simulations of Wind Bubbles We present the first systematic numerical investigation of the dynamics of bubbles driven by super-Eddington flows, a phenomenon that plays a universal role in astrophysical systems ranging from the growth of supermassive black holes in the early universe to luminous sources in the nearby universe. The large-scale propagation of accretion disk winds is essential for constructing a complete physical picture of phenomena such as ultraluminous X-ray sources (ULXs) and Little Red Dots (LRDs). To address this issue, we for the first time perform three-dimensional moving-mesh hydrodynamical simulations, focusing on bubble nebulae around ULXs, using the state-of-the-art code AREPO. The simulations show that the bubble morphology is set by the initial outflow momentum, whereas the mechanical power affects only its size. Comparison with the ULX bubbles NGC 55 ULX-1 and NGC 1313 X-2 indicates that the high-velocity outflows in these systems are confined within a narrow funnel.
11:30	Matteo Imbrogno	Four shalt thou (not?) count: new detections of mHz quasi-periodic oscillations in pulsating ULXs Quasi-periodic oscillations in the mHz range (mHz QPOs) have been detected in different X-ray binaries, hosting either a neutron star or a black hole. Nonetheless, the presence of mHz QPOs in a few ULXs was initially interpreted as the footprint of accreting intermediate-mass black holes. The detection of mHz QPOs first in M82 X-2, and then in M51 ULX-7 (two known pulsating ULXs), however, has demonstrated that this feature is also present in neutron stars shining at super-Eddington luminosities. Additionally, the similar properties of the QPOs in these two pulsating ULXs (a stable centroid frequency and rms) suggest that they could represent a peculiar feature of this class of extreme neutron stars. In this talk, I’ll present the results of our analysis on two other pulsating ULXs, namely NGC 7793 P13 and NGC 5907 ULX-1. We significantly detect a mHz QPO in multiple observations of NGC 7793 P13. I will show how the properties of this QPO align with those of M82 X-2 and M51 ULX-7, supporting the hypothesis that they represent a common feature among pulsating ULXs. I will also show how NGC 5907 ULX-1 could be the fourth pulsating ULX with a mHz QPO, although, in this case, the feature is only marginally detected.
11:45	Roberta Amato	Statistical Analysis of Spectral Models and Parameter Distributions in ULXs Spectra of ultraluminous X-ray sources (ULXs) span a broad range of fluxes and hardness ratios, influenced by factors such as system geometry, inclination, super-orbital variability, and state transitions. While a self-consistent physical model of super-Eddington accretion flows is still lacking, phenomenological models have been widely used to infer the physical properties of ULXs. In this contribution, I will present a statistical analysis of nearly 1,000 XMM-Newton ULX spectra fitted with four different (multi-component) spectral models. I will discuss the quality of the fits, compare model performances, analyze the distributions of best-fit parameters, and explore their physical implications.
12:00	Roberto Soria	What is powering the mysterious super-critical outflow in NGC 5408 X-2? The nearby starburst galaxy NGC5408 (d=4.9 Mpc) contains an exceptionally powerful, compact source whose nature remains a mystery. It is the brightest radio source in that galaxy, more luminous than any radio supernova remnant or shock-ionized ULX bubble known to-date in the local universe. Its luminosity density at 5 GHz is 10 times higher than that of Cas A. Radio flux variability over a few years' timescale suggests that the emission is at least partly associated to a flaring compact object accreting at super-Eddington rates. Broad Balmer and He I emission lines (sometimes with a P Cyg profile) suggest a dense outflow with speeds of at least 5000 km/s, higher than possible from any massive stars, and probably a key signature of super-critical accretion. In addition, strong photo-ionized (narrow) He II 4686, [Ar IV], [O III] components suggest an intrinsic EUV/soft X-ray luminosity L_{XUV} = several x 10^{40} erg/s, mostly blocked along our line of sight. We suggest that the source has a powerful jet with core/hot-spot structure, separated by about 0.7 arcsec (about 15-20pc), and that it is undergoing a violent, short-lived evolutionary phase.
12:15	Sandro Mereghetti	The peculiar variability of A 0538-66: a transient ULX in the Large Magellanic Cloud ? The source A0538-66, located in the Large Magellanic Cloud, contains the fastest-spinning neutron star in an accreting X-ray binary and shows a combination of extreme properties unmatched in other NS/Be systems. It is characterized by extraordinary multi-wavelength variability, including sporadic episodes of seconds-long X-ray flares with a dynamic range >1000 and peak luminosity exceeding 1E38 erg/s, which are correlated with bright, fast optical flares. The fast pulsations (69 ms), discovered in the 80's during a super-Eddington outburst and never re-observed for almost 40 yrs, were recently detected at a much lower luminosity level, challenging our understanding of accretion physics. In 2025, A0538-66 also displayed an outburst reaching super-Eddington luminosity. I will present the most recent results on this binary system from multi-wavelength data and discuss how they constrain the physical mechanisms, such as magnetic field geometry and accretion flow dynamics, responsible for its unique variability.
12:30	Lunch break
	Chair: Luis Abalo	X-ray binaries and ULXs
14:30	Peter Kosec	Review talk Review talk
15:00	Federico Vincentelli	Radiation pressure instabilities in highly accreting neutron stars It has been known for nearly 50 years that the innermost regions of viscous accretion disks become unstable when the luminosity reaches a significant fraction of the Eddington limit. In this regime, radiation pressure becomes dominant, such that cooling overwhelms heating, leading to cyclic depletion and rebuilding of the disk on short timescales. Despite its fundamental importance, this process—known as the radiation pressure instability—remains elusive and not fully understood. Recently, radiation pressure instability has been identified in highly accreting neutron stars, opening a new observational window onto this phenomenon, particularly in relation to disk irradiation. In this talk, I will show how new fast, multi-wavelength observations of Swift J1858 and the archetypal highly accreting neutron star Sco X-1 support this scenario, shedding light on the physical origin of their complex variability. Finally, I will present the first results of modelling radiation pressure instabilities in neutron-star accretion flows, highlighting how irradiation dramatically alters their observable signatures.
15:15	Grzegorz Wiktorowicz	ULXs in Globular Clusters: Dynamics, Escapers, and IMBHs ULXs in globular clusters (GC) remain poorly understood, with only ~20–30 observed cases, all extragalactic. Using the MOCCA Monte Carlo code, we present the first systematic study of ULX populations in GCs, showing that cluster dynamics profoundly reshapes their demographics. Non-tidally filling clusters sustain significantly higher ULX rates over billions of years. The observed scarcity of ULXs in Milky Way GCs is broadly consistent with their initial tidally filling rather than a genuine suppression of progenitor formation. Additionally, we identify a population of "escaper" ULXs, i.e. dynamically formed in GC, then ejected into the field, potentially unrecognised contributors to the field ULX population. IMBH-powered ULXs rarely form in GC, but remain intermittently active across a full Hubble time. Together, these results establish GCs as a unique and underappreciated environment for extreme accretion physics.
15:30	Manish Kumar	From Spectral Properties to X-ray Reprocessing in ULXPs/ULXs: A Comparative Study with Galactic X-ray Binaries Ultra-luminous X-ray sources (ULXs) are highly luminous, off-center X-ray sources that exceed the Eddington luminosity for stellar-mass compact objects. A subset of ULXs has been identified as accreting neutron stars through the detection of coherent X-ray pulsations (∼1–30 s). These ULX pulsars (ULXPs) challenge earlier models invoking intermediate-mass black holes and require accretion models distinct from those of Galactic black hole binaries. We present a broadband spectral analysis of five ULXPs using simultaneous XMM-Newton and NuSTAR observations. Their spectra are well described by models typically used for local accreting X-ray pulsars, including a high-energy cut-off power law and a soft excess, consistent with low absorption. We have marginal detection or a low upper limit on the presence of iron Kα emission line from these sources, which is a key difference of the ULX pulsars from the local accreting X-ray pulsars. We discuss the implications of this on the nature of the binary companion and the accretion mechanism in the ULX pulsars. Furthermore, we examined X-ray reprocessing signatures in ULXs by focusing on three aspects: (i) the presence of Fe Kα emission lines in bright ULXs and ULXPs, (ii) hardness ratio variations during the eclipse transitions, and (iii) the eclipse-to-out-of-eclipse (OOE) flux ratio in eclipsing ULXs. We place stringent upper limits (11–20 eV) on Fe line equivalent widths, detect no significant hardness changes during eclipse transitions, and find that the reprocessing efficiency (eclipse-to-OOE flux ratio) is higher in ULXs than in Galactic X-ray binaries. These results suggest that ULXs are likely embedded in metal-poor or highly ionized environments, which strongly suppress reprocessed emission features.
15:45	Tanuman Ghosh (remote)	Neutron Stars as Engines of ULXs and HLXs Ultraluminous X-ray sources (ULXs) provide valuable laboratories for studying extreme accretion, as their luminosities often exceed the limits expected for standard stellar-mass black hole systems. These objects were historically interpreted as candidates for intermediate-mass black holes (IMBHs). However, growing observational evidence, including confirmed neutron stars in several ULXs and detailed broadband X-ray spectral studies, now increasingly favors super-Eddington accretion onto compact stellar remnants as a plausible explanation. Hyperluminous X-ray sources (HLXs), with luminosities above 1e41 erg/sec, have generally been considered strong IMBH candidates. Nevertheless, the possibility that neutron stars may also power some HLXs challenges this conventional view and motivates a closer examination of their physical nature. In this talk, I analyze the spectral characteristics of both ULXs and HLXs using a newly developed physically motivated model that supports neutron stars as the primary accretors. Special emphasis is placed on NGC 470 HLX-1, a highly variable HLX that displays a soft thermal spectral component and indications of high-energy synchrotron emission, consistent with a neutron-star-driven scenario. I will further discuss key aspects of particle acceleration in accreting neutron star systems, focusing on how magnetic field structure, accretion geometry, and magnetospheric or shock-related processes can facilitate efficient particle energization. These considerations strengthen the case for synchrotron emission in such environments and suggest that HLXs, like ULXs, may not necessarily require IMBHs to account for their observed properties. Future broadband X-ray observations, combined with improved theoretical modeling, will be essential for clarifying the underlying accretion physics, particle acceleration mechanisms, and the true nature of these extreme high-energy sources.
16:00	Coffee break
	Chair: Dimitrios Maniadakis	X-ray binaries and ULXs
16:30	Dominic Walton	A ~40d X-ray Period in NGC2283 ULX1 Detected by Swift/XRT Following a series of remarkable discoveries, we now know that some of the most extreme members of the ultraluminous X-ray source (ULX) population are actually powered by highly super-Eddington pulsars. These enigmatic sources can exhibit varied and complex long-term behaviour, but one facet many of the known ULX pulsars have in common is the presence of long-timescale (10s of days) X-ray periodicities seen in their long-term monitoring data. These are mostly understood to be super-orbital in nature, likely involving some kind of precession of the accretion flow, and may thus be of significant interest with regards to understanding super-Eddington. Here we report the detection of a new, high-amplitude ~40d periodicity in the (otherwise) poorly studied ULX in NGC2283, based on recent monitoring with the Swift/XRT. The properties of these variations in NGC2283 ULX1 show notable phenomenological similarities to the long-term X-ray periods seen in several of the known ULX pulsars, potentially identifying NGC2283 ULX1 as a promising ULX pulsar candidate.
16:45	Simona Caserta	A shocked, biconical outflow in an ultraluminous X-ray source revealed by high-resolution X-ray spectroscopy Ultraluminous X-ray sources (ULXs) are among the most extreme X-ray binaries with luminosities exceeding the Eddington limit for a stellar-mass black hole. The majority of ULXs are powered by compact objects accreting at super-Eddington rates and are characterised by relativistic outflows, observed through absorption and emission lines in high-resolution X-ray spectra. Until now, exciting discoveries have been made in this field, although there are several unsolved questions, such as the dependence of the wind on the accretion rate and its role in determining ULX spectral transitions. In an attempt to tackle these issues, we have triggered deep campaigns with XMM-Newton to study the disc-wind connection in variable ULXs. Here, I will present our results obtained for the cornerstone ULX NGC 5204 X-1. Using physically-motivated plasma models, we identified two collisionally ionised plasma components moving in opposite direction along the line-of-sight, both with velocities of about 0.3c. These findings have high statistical significance and suggest a biconical outflow geometry. This represents the first evidence for a biconical outflow in a ULX, analogous to that observed in the X-ray source SS 433, the only known super-Eddington accretor in our Galaxy. Additionally, I will present new results for the persistent ULX NGC 4190 X-1, using recent XMM-Newton observations from our recent campaign, combined with NuSTAR data. High-resolution X-ray spectroscopy of these sources improves our understanding of super-Eddington accretion and offers insights into the geometry of binary systems accreting in this extreme regime.
17:00	Anastasia Kilina	NGC 253 ULX-1: Bubble of ionized gas and optical/NIR counterpart Ultraluminous X-ray sources (ULXs) are accreting stellar compact objects whose X-ray luminosities exceed the Eddington limit. Most of them are thought to harbour a neutron star or a stellar mass black hole accreting at Super-Eddington rates. In order to understand these accretion processes, it is useful to look at the interaction of ULXs with their environment. Some ULXs have been found to have bubbles of ionized gas around them. We use the data from the VLT/MUSE 3D spectrograph to study such a bubble around NGC 253 ULX-1. Our aim is to understand whether it is X-ray photons and/or shocks from the accretion disk winds that are the main sources of ionization of the interstellar medium surrounding NGC 253 ULX-1. We also study its optical & near-infrared counterpart, which provides information about this ULX's companion star.
17:15	Chiara Salvaggio	A MeerKAT detected ULX radio bubble in NGC 1313 Ultraluminous X-ray sources (ULXs) are a class of extreme X-ray binaries, most of them powered by super-Eddington accretion onto stellar mass black holes and neutron stars. Extended optical or radio emission (and a single case in X-rays) has been observed around some ULXs, with a bubble-like shape. These huge bubbles have diameters > 100 pc and contain an energy 10-100 times larger than the energy content of supernova remnants. ULX bubbles are thought to be shock-ionized, formed by the interaction of ULX outflows (winds or jets) with the surrounding interstellar medium. The study of ULX bubbles is crucial to understand the feedback of these extreme accretors on the surrounding environment. In this talk, I will focus on the results obtained from the analysis of a MeerKAT dataset of the ULX bubble around NGC 1313 X2, which is the first radio detection of this bubble, previously observed only in the optical. At least two different emitting regions can be identified in the radio map, one brighter and one weaker, with a compact and a steep spectral shape, respectively. The bubble dimension as seen in the radio is consistent with the Halpha emission from MUSE data: I will show a comparison of the morphology at radio and optical wavelengths. Finally, I will discuss the results from the study of this bubble in a larger context, including a comparison with Galactic X-ray binaries, first of all the extreme SS433 and its W50 nebula.
17:30	Davey Dickson (remote)	Donor Dynamics: How to Power a ULX Ultraluminous X-ray sources (ULXs) are able to exceed the Eddington limit to achieve remarkable luminosities due to high-energy accretion onto a compact object. This requires a powerful source of fuel, such as the donor star companions found in X-ray binaries. Yet the mass transfer required to supply that fuel to the accretor has long been mired by the computational complexity of interdependent feedback processes. In this talk, I will detail my novel approach to track mass transfer flows from deep within a donor star to the final approach onto the accreting compact object. This high-resolution 3D model pushes forward the state-of-the-art to capture the donor envelope, wind, tidal stream, accretion disk, and x-ray feedback interacting in tandem. This model reveals that material comes both from slow, dense flows deep within the donor as well as rapid, thin surface flows to collide with each other near the L1 Lagrange point, and that this interaction seeds anisotropies in the wind as it launches from the donor's surface. I will share the new constraints and trends this approach has revealed regarding mass and angular momentum transfer and their associated efficiencies in the presence of luminous accretors. These efficiencies depend critically on whether mass accretion occurs primarily through wind, a tidal stream, or a disk fed by either of the two. I will discuss the implications of these results for the formation of ULXs in X-ray binaries as well as the timescale for which they could be sustained at those luminosities. The lifespan of these sources is limited by the extent of overflow required, as my results reveal that a difference in overflow of 1% can alter the timescale of mass transfer by more than two orders of magnitude.
17:45	Nabil Brice	Testing Lense-Thirring Precession by Phase-Coherence in NGC5907 ULX-1 The mechanism driving super-orbital modulation in ultraluminous X-ray sources (ULXs) remains an open question. Determining whether such modulation in ULX pulsars originates from Lense-Thirring precession of the inner disc or precession intrinsic to the neutron star has implications for the magnetic field strength required to sustain super-Eddington luminosities. Since the Lense-Thirring period depends strongly on the mass accretion rate whereas neutron star precession does not, monitoring the super-orbital period over changing accretion rates could discriminate between the two scenarios. NGC5907 ULX-1, the most luminous ULX pulsar (peak luminosity 10^41 erg/s; ~500 times the neutron star Eddington limit), provides an ideal test case. The source exhibits a super-orbital modulation with a stable 78d period yet underwent an extended quiescent state (mid-2017--mid-2020) associated with sub-Eddington luminosities (likely propeller regime), before returning to high-flux activity. We present results from >10 years of Swift XRT monitoring (2014--2025). Using Bayesian mixture models to marginalise over intermediate-flux states that obscure the periodic signal in the recent epoch, we recover a tightly constrained period with a fast-rise-exponential-decay profile. We tested phase-coherence across the ~14-cycle quiescent gap, finding evidence for a stable underlying clock. This result challenges the Lense-Thirring scenario, where maintaining phase-coherence despite disruption to the inner disc would be highly coincidental. Instead, our results suggest a mechanism independent of the accretion state, possibly intrinsic to the neutron star itself. Thus, super-orbital timing serves as an independent probe of the magnetic field influence on the accretion flow in the super-Eddington regime, complementing spectral and pulsation diagnostics.
18:00	Discussion (Dominic Walton)
18:30	End of day

Friday

	Chair: TBD	Final session
9:00	Natalie Webb (remote)	Review talk Review talk
9:30	Chichuan Jin	Super-Eddington Accretion in Tidal Disruption Events and New Insights from Einstein Probe Tidal Disruption Events (TDEs) reveal the complete dynamic evolution of Supermassive Black Holes (SMBHs) from super-Eddington to sub-Eddington accretion processes. With the recent advancements in time-domain astronomy, significant progress has been made in the field of TDEs, offering new and valuable observational insights into the super-Eddington accretion of SMBHs in general. In this talk, I will briefly review some of the key observational advances in recent TDE studies and make preliminary comparisons with super-Eddington AGN. Additionally, I will introduce some early but exciting discoveries of X-ray TDEs from the Einstein Probe (EP), an X-ray time-domain survey telescope launched in 2024, and discuss the prospects for EP's future contributions to the field.
10:00	Andrea Contu and Claudia Lazzaro	Discover the nature of Black Holes in the Einstein Telescope era The Einstein Telescope (ET) is the next generation of ground-based gravitational-wave observatories, with a sensitivity improvement of approximately one order of magnitude over current detectors. The detection of binary black hole (BBH) mergers by the LIGO-Virgo-KAGRA (LVK) interferometers opened a new era in gravitational-wave astronomy, providing unique opportunities to investigate the nature of black holes. Starting from the last discoveries of LVK, we will examine how the enhanced sensitivity of ET is expected to revolutionize the field, enabling high-precision tests of black hole physics, and the fundamental predictions of general relativity.
10:30	Coffee break
11:00	Ruchi Mishra	Equilibrium tori orbiting Reissner-Nordström black holes and naked singularities We explore the equilibrium shapes of barotropic fluid tori with uniform angular momentum in the gravitational field of a Reissner-Nordström (RN) naked singularity. The RN metric represents a charged, static, spherically symmetric source of gravity. When the charge exceeds the mass, the central object becomes a naked singularity, with unique features such as a "zero-gravity" sphere where test particles can theoretically remain at rest. For fluids with angular momentum, the equilibrium structures are toroidal, either fully or partially outside the zero-gravity sphere, with maximum pressure occurring beyond this sphere. Interestingly, unlike black holes, a fluid cannot accrete onto the singularity; bound fluid remains in orbit within the torus, while unbound fluid escapes to infinity in jet-like outflows. These findings may provide insights into toroidal structures observed in images of Sgr A* and M87 by the Event Horizon Telescope.
11:15	Akash Garg	Capturing the Nature of X-ray Transients through Neuro-Parametric Machine learning Methods Low-mass X-ray binary transients undergo recurrent outbursts, briefly dominating the X-ray sky. Determining the nature of the compact object in such systems, whether a black hole or a neutron star, remains challenging, particularly during the early phases of an outburst. Traditional classification relies on detailed analyses of complete light curves, power spectra, and broadband energy spectra, which can be challenging for the rapid identification of a large number of sources. With the advent of multiple X-ray missions over the past three decades and the recent launch of wide-field monitors such as SVOM and Einstein Probe, there is an increasing need for fast, scalable, and mission-independent classification techniques. In this work, we employ neuro-parametric machine-learning methods to infer the nature of X-ray binary transients using limited spectral information. Using archival RXTE data, we develop three neural-network models trained on: (i) spectral flux values, (ii) spectral fluxes with their associated uncertainties, and (iii) physically motivated accretion parameters obtained from spectral fitting. We achieve classification accuracies of 90–94% in distinguishing black hole and neutron star transients. Importantly, the model based on accretion parameters is largely mission-agnostic, allowing for a straightforward extension to current and future X-ray surveys. This approach provides a pathway toward rapid and automated characterization of X-ray transients.
11:30	Sina Chen	Radio probes of AGN winds in high Eddington ratio AGN High Eddington ratio (L/L_Edd > 0.3) AGN are likely to launch a radiation-driven wind. Does this wind interact with the ambient medium and produce radio emission? I will present a study of the correlations between a parsec-scale radio wind and a broad-line region (BLR) wind in a sample of 20 radio-quiet quasars. The radio wind is defined based on the spectral slope and the flux compactness of the 1-5 GHz parsec-scale emission, and the BLR wind is defined by the excess blue wing in the C IV emission line profile. The high Eddington ratio objects are found to have both radio and BLR wind indicators. This suggests that the BLR wind extends to parsec scales and produces radio emission. Radio is a key to probe the interaction between the AGN winds and the ambient medium.
11:45	Final round table
12:30	End of conference

Code of conduct for Breaking the Limits 2026

We value the participation of everyone at this conference and want all attendees to have an enjoyable and fulfilling experience. Accordingly, all attendees are expected to show respect and courtesy to other attendees and staff.

As such, Breaking the Limits 2026 will be a harassment-free event for everyone, regardless of gender, sexual orientation, disability, physical appearance, body size, race, nationality, religion. We do not tolerate harassment of attendees in any form.

• Harassment includes offensive verbal comments related to gender, sexual orientation, disability, physical appearance, body size, race, religion, sexual images in public spaces, deliberate intimidation, stalking, following, harassing photography or recording, sustained disruption of talks or other events, inappropriate physical contact, and unwelcome sexual attention.


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In addition to this, please keep in mind that presenters give their time freely, many have travelled a considerable distance, some are very distinguished, some are early career scientists perhaps presenting their work at this level for the first time, and all deserve a fair and encouraging hearing. Please try to be on time for the start of a session, refrain from loud conversations outside the doors, mute mobile phones, and if you must use a lap-top computer do so inconspicuously.

Thank you for helping make this a welcoming, respectful space for all.

(This document was adapted from the Code of Conduct for RAS Meetings)