Netherlands Astronomy Conference 2026

5 min - SRON
5 min - KNA-RNAS
5 min - LOC

We present our ongoing development of radio astronomy instrumentation and the science drivers behind it. Two examples of our work include L‑FIRE (Low‑Frequency Interferometric Radio Explorer), a concept for a distributed radio telescope in low Earth orbit, and contributions to the DEX (Dark Ages Explorer) lunar radio telescope concept. We analyse how our targeted science cases shape the necessary instrument performance and prototype low‑frequency antenna concepts that enable those measurements. Our science cases include, for example, radio detection of exoplanets and AI‑based classification of solar radio bursts. In parallel, we established a project-based Radio Astronomy track within the TU/e Honours Academy, enabling students to engage in astronomical data analysis and instrumentation design, and to prepare them for future careers in astronomy.

The discovery of gravitational waves has transformed astrophysics, enabling the study of the Universe in a fundamentally new way. The next major breakthrough is expected with the launch of the European Space Agency’s Laser Interferometer Space Antenna (LISA) in the mid-2030s. By opening the millihertz gravitational-wave window, LISA will access a rich population of astrophysical and cosmological sources that are largely inaccessible by other means.
In this talk, I will provide a brief update on the status of the LISA mission and highlight its expected impact on Galactic stellar astrophysics. LISA will detect and characterise tens of thousands of compact binaries — white dwarfs, neutron stars, and black holes — across the Milky Way, most of which are electromagnetically faint or entirely invisible. I will show how these Galactic LISA sources enable the first gravitational-wave map of the Milky Way’s stellar remnant population and help address long-standing questions such as the nature of Type Ia supernova progenitors. Finally, I will outline my vision for strengthening and coordinating LISA science activities in the Netherlands, with the aim of building a coherent national effort that connects instrumentation, data analysis, and astrophysical modelling in preparation for LISA’s scientific return.

Unintended electromagnetic radiation (UEMR) from large Low Earth Orbit satellite constellations poses a growing threat to radio astronomy. First identified with the Low Frequency Array (LOFAR), this weak but persistent emission from onboard electronics can be broadband and difficult to mitigate, yet is strong enough to contaminate sensitive observations.

Follow-up measurements with other instruments show that UEMR is widespread across a broad frequency range, putting current and future radio telescopes at risk. This threatens key science cases, including studies of the early Universe, for both ground-based observations and planned radio astronomy on the Moon.

Regulatory frameworks within the International Telecommunication Union (ITU) Radiocommunication Sector (ITU-R) do not adequately address UEMR yet, as they focus on intentional transmissions. In parallel, standardisation efforts are emerging in ISO and CISPR.

This contribution presents recent observations, their scientific impact, and ongoing regulatory and standardisation efforts.

The modeling of stars and stellar populations is a key element in our understanding of the Universe, and plays a large role in the scientific exploitation of observations as astronomy moves into the big data era. However, despite the identification of the key processes and fundamental equations that drive stellar evolution almost a century ago, and the broad availability of numerical methods to model stellar evolution, several important questions remain. In this talk, I want to delve into the methods used in the present to model stellar evolution, how these have evolved since the first numerical simulations of the early 60s, and how further progress can be made in the field. In particular, I will highlight how new developments coming both from new observations (such as gravitational wave sources and exotic supernovae) and theoretical uncertainties are pushing the limit of what we can achieve with our current tools. Despite the progress in computational hardware given by Moore's law, the long time-scales of stellar evolution remain restricted to 1D evolutionary calculations, while complex 3D phenomena can only be traced for short dynamical evolutionary timescales. I will highlight how progress in key areas requires a careful interfacing between 1D and 3D results, and emphasize the very important role of open science and open source in the field.

We have just passed the 10th anniversary of the first-ever gravitational-wave detection. With more than 150 detections of merging binary black holes (and counting), gravitational-wave observations have entered the ‘population era’. The data already reveal a rich structure in the black hole mass function. However, for the first time, we have now obtained enough detections to begin identifying sub-populations within the larger binary black hole population.

These sub-populations might help us identify families of binary black hole mergers that share a common origin (i.e., have the same formation channel). In particular, certain binary interactions (like stable mass transfer) are expected to leave measurable imprints on the properties of merging binary black holes. I will discuss what different binary interactions predict, what we currently observe in the gravitational-wave population, and how these observations already allow us to place meaningful constraints on, and in some cases exclude, specific formation channels.

Images are among the most important tools astronomers use to understand the Universe. As machine learning techniques are increasingly used in astronomy, we explore what machines “see” in galaxy images, with a particular focus on galaxy morphology. 

Galaxy morphology provides one of the most direct observational signatures of evolutionary pathways, making its taxonomy a central pursuit in astronomy for over a century. Traditional classification schemes, most notably the Hubble sequence, rely heavily on visual inspection and human-defined categories. While foundational, these frameworks may not fully capture the diversity and complexity of structures revealed by modern imaging surveys. In this talk, I will present previous works applying machine learning techniques to the study of galaxy morphology from images, highlighting how data-driven approaches can uncover new perspectives on the structural diversity of galaxies beyond conventional classification schemes.

The Near-Ultraviolet eXplorer (NUX) is a proposed wide-field (~67 square degrees) ground-based observatory, designed to explore the shortest UV wavelengths (300 to 350 nm) observable from Earth's surface. NUX’s primary goal is to deepen our understanding of fast (hours to days) and hot transient phenomena, including shock-breakout emissions from supernovae and electromagnetic sources associated with gravitational wave events. The system features four modified 36cm Celestron RASA telescopes, each enhanced with custom near-UV optics and a Near-UV sensitive camera. To validate the scientific and technical feasibility of NUX, we have built a prototype telescope (proto-NUX). After successful initial testing in the Netherlands to evaluate its technical performance, we will perform further tests to determine the NUV characteristics of the atmosphere in March 2026 at Pic du Midi observatory. During my presentation I will present proto-NUX and the outcomes of these tests and their implications for potential necessary adjustments to the final NUX design.

Jupiter’s famous banding reflects powerful jet streams that probe deep atmospheric and interior processes. Since arriving in 2016, NASA’s Juno spacecraft, in a series of close, polar perijove passes, has returned high-precision gravity measurements from its Gravity Science experiment (tracking Doppler shifts of the spacecraft), alongside complementary data from the Microwave Radiometer and Magnetometer, enabling unprecedented constraints on mass anomalies, deep atmospheric structure, and magnetic-field–flow interactions. These gravity data indicate jets extend thousands of kilometers but leave the detailed vertical decay uncertain because it depends on the assumed interior density distribution, among other uncertainties, typically taken as adiabatic. Here we examine how subadiabatic (stable) layers beneath the weather layer modify the density structure and thus Jupiter’s gravity signal; using temperature–pressure profiles with plausible stable stratification and a modern equation of state, we show such layers can substantially alter background density and interact with wind-induced mass anomalies to widen the range of vertical wind profiles consistent with measured gravitational harmonics, implying that assuming a purely adiabatic interior can falsely tighten constraints on jet depth and that independent constraints on Jupiter’s internal stability are needed to uniquely determine how deep the jets penetrate. We also compare gravity-implied vertical structures with profiles from numerical simulations and Earth analogs to assess typicality, and conclude by emphasizing the strong degeneracy between thermodynamic stratification and wind decay, highlighting the need for complementary future observations and targeted modeling to break this degeneracy and robustly infer Jupiter’s deep jet structure.

To understand the origin of heavy elements, it is crucial to understand early star-forming activity. Observations with the James Webb Space Telescope have unveiled more early galaxies than expected, highlighting the need for complementary tracers of obscured star-formation in the early Universe.
(Sub)millimetre spectroscopy provides direct access to dust emission and far-infrared fine-structure lines such as [C II], one of the brightest coolants of the interstellar medium. Although interferometers like ALMA and NOEMA possess a very high sensitivity at these frequencies, they are inefficient for large surveys due to their limited field-of-view and instantaneous bandwidth. Direct-detection cameras provide wider fields of view, but no spectral information, rendering them unable to map the line-of-sight.
We are developing TIFUUN (Terahertz Integrated Field Units with Universal Nanotechnology). This imaging spectrometer with hundreds of spectral channels uses kinetic inductance detectors to rapidly map the early Universe in three dimensions. TIFUUN will be used efficiently for line intensity mapping through SUBLIME (Study of the Universe By Line Intensity Mapping Experiments) In line intensity mapping, the integrated emission of a spectral line over various spatial scales is studied. In this way, numerous faint galaxies that are difficult to detect in isolation can be probed. SUBLIME-TIFUUN targets the [C II]-line, providing power spectra between z=4.9 and 8.7.
TIFUUN is designed with SUBLIME in mind, to control for low-redshift interlopers and achieve maximal mapping speed with large single-dish telescopes such as ASTE, FYST, and APEX. In this talk, we discuss the development of TIFUUN, its planned data-scientific methods for analysis and the theoretical prognosis for SUBLIME.
The creation of SUBLIME-TIFUUN will offer a unique view into the early Universe, enabling new insights into galaxy formation, the production of heavy elements in the early Universe, and possibly new insights into cosmology.

Several extragalactic Fast X-ray transients (FXTs), detected as bursts of soft X-ray photons with durations of hundreds of seconds by the Einstein Probe mission, have recently been linked to the collapse of a massive star. For those FXTs, the ensuing supernovae are similar to those associated with long gamma-ray bursts (long-GRBs). Under the fireball model for long-GRBs, the collapse of a rapidly rotating, stripped envelope, massive star gives rise to a relativistic jet that powers the gamma-ray burst. It has been proposed that a population of fireball explosions exists with lower-energy, less relativistic, jets than those of typical GRBs, so-called dirty fireballs. It has been suggested that some FXTs could probe this previously elusive regime.
Here, we report on EP241026b, an FXT discovered at redshift z~2.3 with a delayed afterglow light curve peak. We model the optical and X-ray light curves using a tophat jet model and investigate the origin of the long-lasting X-ray plateau phase. We conclude that EP241026b is driven by a mildly relativistic outflow with a Lorentz factor of the jet of ~22, which is among the lowest detected for GRBs and FXTs to date. The low Lorentz factor, long X-ray plateau phase, and absence of a detection in gamma-rays provide compelling observational evidence for a dirty fireball explosion as the origin of EP241026b.

Dust is a minor constituent of our Galaxy but dominates our view of it. To understand its key role in the lifecycle and energy balance of interstellar matter, we must understand its properties and processing.
X-ray spectroscopy provides a unique tool to study the properties of interstellar dust. The X-ray band contains absorption edges of important components of interstellar dust, such as C, O, Mg, Si, S, Ca and Fe. X-ray absorption fine structures (XAFS) in the edges reveal a wealth of information about interstellar dust properties, e.g. chemical composition, crystallinity and grain size. X-ray binaries are used as background lights to analyse the intervening dust along several Galactic sightlines. XMM Newton and Chandra opened a new window to study interstellar dust using X-ray spectroscopy, allowing to study the Fe L, O K, Mg K and Si K edges. Observations of Galactic X-ray binaries and the development of an X-ray dust database [Costantini 2013] facilitated the exploration of dust in the central part of the Galaxy [e.g. Zeegers 2019, Rogantini 2020], as well as several diffuse sightlines [e.g. Psaradaki 2020, 2023].
XRISM (launched in 2023) and the upcoming NewAthena observatory (2037) allow us to observe the XAFS features at higher energies in the edges of S K, Ca K and Fe K in unprecedented detail. This talk gives an overview of current and future explorations of dust features with XRISM and NewAthena. I will present new dust models that contain different size distributions [Vaia et al. submitted 2026] and new laboratory measurements [Zeegers, Chu et al. in prep.]. Furthermore, I will summarize the impact of X-ray spectroscopy on our knowledge of interstellar dust.

In the last 15 years, the Atacama Large Millimeter/submillimeter Array
(ALMA) has revolutionized astrophysics by providing unprecedented
resolution and sensitivity for observing the cold Universe. However, in
another 15 years from now, the scientific landscape will have changed
dramatically as major new facilities come online, and ALMA itself will
approach its fourth decade of operation. To remain at the forefront of
discovery, the community must consider how transformational new
capabilities in the (sub-)millimeter regime can sustain and expand
ALMA’s scientific leadership in an increasingly competitive global
environment.

The ALMA2040 initiative has been launched to articulate a long-term
scientific and technical vision for the observatory beyond the current
upgrade path. It aims to identify the key capability gaps that will
limit ALMA’s impact in the 2030s and 2040s, and to define ambitious yet
realistic development pathways that could deliver step-change
improvements in sensitivity, bandwidth, and angular resolution. In this
talk, I will introduce the motivation behind ALMA2040, summarize its
current status within the international partnership, and outline the
next steps toward defining and prioritizing future transformational
capabilities.

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TO BE EDITED

The missing baryons, that is, the yet-unobserved ordinary matter in the large-scale structures of the Universe, have been shown by simulations to reside mostly in filaments of the cosmic web. As this phase of the cosmic gas is becoming observable, currently in the outskirts of galaxy clusters and in short filaments, so-called bridges, it is becoming crucial to understand their detailed gas dynamics and its influence on the connected intracluster medium in galaxy clusters towards which the gas is accreted.

I will present preliminary results of a study of the gas dynamics in filaments using a high-resolution zoom-in hydrodynamical simulation of a cosmic filament, showing how gas flows, and in particular turbulence, are shaped by diverse processes such as intermittent accretion shocks or hydrodynamic instabilities.

We present a morphological analysis of dwarf galaxies in the Perseus cluster using Euclid Early Release Observations (ERO), exploiting the VIS instrument's diffraction-limited resolution and exceptional surface brightness sensitivity. Working from the ~1100-dwarf ERO catalog of Marleau et al. (2025), we develop a novel cumulative light fraction approach for measuring isophotal shapes in low surface brightness systems. Rather than tracing contours at fixed surface brightness levels — which is unreliable in noisy regimes — we extract isophotes at fixed fractions of the total galaxy flux and quantify the $c_4$ Fourier coefficient, validated to $r > 0.98$ accuracy across SNR 5–100.

Applying this method to 804 early-type Perseus dwarfs, we identify 13 galaxies with significantly boxy isophotes ($c_4 < -0.0175$). These systems are red, fully quenched, and show no disk or spiral features despite Euclid's resolution. We find a strong anticorrelation between $c_4$ and effective radius ($r = -0.75$, $p = 0.003$): the physically largest dwarfs are the boxiest.

To interpret this, we generate synthetic Euclid observations of tidally transformed dwarf simulations (Smith et al. 2021) across 240 viewing angles. The size–shape correlation arises naturally from projection effects: face-on orientations simultaneously maximize apparent size and reveal the full rectangular profile of a tidally induced peanut structure, while edge-on views yield rounder, more compact morphologies. Dry mergers are disfavored by the elongated axis ratios of the sample and the high velocity dispersion of Perseus. Correcting for viewing geometry, we estimate a parent population of ~30 such tidally transformed, peanutty remnants in Perseus.

The discovery of the phase space spirals in the Solar neighborhood in Gaia Data Release 2 has prompted various attempts to understand their origin. A source of bending waves, which has been neglected as a cause of the phase spiral, is irregular gas inflow along the warp.
We aim to study whether perturbations by the gas warp could induce phase spirals. Accounting for this additional formation scenario for phase spirals could improve our current understanding of the perturbation history of the Milky Way disc.
We use two $N$-body$+$SPH (Smooth Particle Hydrodynamics) simulations of an isolated galaxy to search for, and study, warp-induced phase spirals. We study the emergence and propagation of the detected phase spirals using Fourier decomposition.
We detect strong one-armed phase spirals in the warped simulation. These phase spirals are prevalent and persist over $\sim 10$ Gyr. The morphology of these phase spirals varies with location and evolves with time. In particular, the emergence rate of the phase spiral evolves with the gas inflow at the outer disc and the bending wave amplitude, indicating that these phase spirals are a record of warp-induced bending waves. We find that these phase spirals can reach amplitudes comparable to those in the Gaia DR3. We only detect weak and stochastically-distributed phase spirals in an unwarped control simulation.
We conclude that phase spirals can be induced by the irregular gas accretion along the warp. These phase spirals occur globally and are long-lived.

The extended hot ($T=10^6$ K) gas phase of the circumgalactic medium (CGM) is an essential component for studying the baryon cycle of late-type galaxies, because it could supply the galaxy with gas to sustain star formation and possibly contains many of the 'missing' baryons.
Using a simple semi-analytic model based on hydrostatic equilibrium and the latest eROSITA observations, we evolve the hot CGM gas subject to radiative cooling, photoionization and mechanical heating from a central source. In the absence of mechanical heating, we see that gas at large radii flows inwards at a constant rate, but in the inner kpc it cools rapidly. By including mechanical heating, we estimate the power that is needed to stop this inflow. Our results show that a source that could have created the Fermi bubbles is sufficient to halt the rapid inflow and form a self-regulating cycle with the hot CGM (analogous to cooling flows and AGN feedback in clusters) that keeps it stable for a long time.
If this is indeed the case, direct accretion of gas from the hot CGM will be suppressed and therefore we need another mechanism to sustain the constant star formation in the galaxy. In future work, we therefore focus on the cool phase of the CGM, where we perform ultra high resolution magneto-hydrodynamical simulations to study the evolution of these clouds under various conditions. By comparing the results of these simulations to observations, we can learn where these clouds originate and whether they are able to accrete onto the galaxy and supply enough gas to sustain star formation.

In the interstellar medium, multiple processes in star formation and
evolution deposit, clear, and reorganize dust molecules around stellar
populations. In the Physics at High Angular Resolution in Nearby
Galaxies (PHANGS) surveys, stellar associations trace loosely bound
young stars in recent star formation sites. Leveraging the synergy
between HST and JWST, we measure dust extinction of stellar associations
in NGC 4826 (M 64) using the Hα to Paschen-α decrement. Combining this
robust extinction metric with SED modeling, we refine age measurements
of stellar populations. We further correlate stellar properties with
dust emissions from polycyclic aromatic hydrocarbons (PAH) as seen by
JWST. We tentatively note a drop in dust extinction around 7 Myr in 16
pc stellar associations, which roughly coincides with the clearing of
PAH emission. Our study explores the enrichment and dispersion of PAH,
connects stellar and dust properties, and reveals their mutual influence
on each other.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous ingredients of the interstellar medium where they contain 15 to 20% of all the carbon and play a crucial role in the ionization balance and gas heating (Tielens et al., 2008). PAHs produce bright emission spectral features called the Aromatic Infrared Bands (AIBs), which are detected in great detail thanks to the exquisite spectral resolution of the James Webb Space Telescope. This new and very informative data calls for a more sophisticated emission model for PAHs that considers important properties such as anharmonicity. ALPAHCAS (Anharmonic Level calculations of PAH Cascade emission and Absorption Spectra), an open-source package which builds upon code developed by Mackie et al. (2018), can calculate detailed absorption and emission spectra of PAHs based on Density Functional Theory (DFT). To assess the quality of our DFT calculations, we performed a benchmark of different model chemistries against the experimental absorption spectrum of the pyrene cation obtained at the HFML-FELIX (Panchagnula et al., 2020). We find that our optimal model chemistry (B3LYP/N07D) shows a very good agreement with the experiment, with an absolute average deviation of 2.6 nm (relative deviation of 0.29%) and a maximum deviation of 9.6 nm (relative deviation of 1.1%). This is then used to compute the emission spectrum, where we can reproduce spectral signatures and their features as seen in JWST observations. In future work, ALPAHCAS will be expanded to include more photophysical processes, and will be used to calculate spectra of larger cationic PAHs to construct a size tracer for relevant astronomical environments. This Project is financially supported by the Dutch Astrochemistry Network of the Dutch Research Council (NWO) under grant no. ASTRO.JWST.001.

We investigate a dust-driven vertical shear instability (DVSI) in a radially local, vertically stratified isothermal shearing box. Unlike the classical vertical shear instability, which relies on baroclinicity from global thermodynamic gradients (radial temperature gradients with finite cooling), DVSI is triggered by dust backreaction that generates axisymmetric vertical shear in an otherwise barotropic setup. We construct vertically stratified two-fluid equilibria including dust diffusion and use these profiles to initialise 2D hydrodynamical simulations with FARGO3D. To cleanly separate DVSI from drag-driven instabilities, we primarily adopt a “dust-analogue” approach in which dust backreaction is imposed as a prescribed height-dependent acceleration on the gas, with no dynamical dust feedback. DVSI grows fastest in off-midplane layers where the vertical shear is strongest, exciting predominantly radially short, vertically extended modes (large kx/kz). During the linear phase, the instability produces characteristic banded perturbations in the azimuthal and vertical velocities. In the non-linear regime, DVSI saturates via a Kelvin–Helmholtz-like parasitic instability that disrupts coherent vertical-shear modes into smaller-scale eddies. The resulting balance between mode growth and parasitic breakup sustains anisotropic turbulence and persistent vertical stirring. Our results demonstrate that dust-induced vertical shear alone can drive vertical mixing in an isothermal local model, without invoking global thermal gradients.

Atmospheric boundary conditions play a critical role in interior modeling, as they define the interior adiabat and strongly influence the inferred planetary radius for a given interior structure. For hot Jupiters, their extended and highly irradiated atmospheres enable detailed observational constraints on atmospheric composition, now reaching unprecedented quality with JWST and ground-based instruments. While previous interior structure retrievals have incorporated simplified atmospheric constraints, such as metal enrichment, they rarely include the richer chemical information that is now becoming available. In this talk, we show how atmospheric composition, specifically the metal enrichment ([M/H]) and C/O ratio, affects interior properties of hot Jupiters. We also illustrate how assuming simplified atmospheric compositions, such as a solar C/O ratio, can bias inferred interior properties. We couple a grid of self-consistent 1D radiative-chemical equilibrium models to a static interior structure model. This framework allows atmospheric composition to be used both as an atmospheric boundary condition and as a chemically informed constraint on envelope metallicity. Consistent with previous works, we find that the planetary radius predicted for a given interior structure depends strongly on atmospheric metallicity because of its direct coupling to the envelope metallicity. In addition, we observe a systematic effect from varying the C/O ratio: for a fixed interior structure, higher C/O ratios generally lead to smaller planetary radii. This effect is most pronounced for hotter interiors and therefore particularly relevant for hot Jupiters. By retrieving the interior structure of WASP-19b with different atmospheric boundary conditions, we show that assumptions about atmospheric composition can alter inferred interior properties, highlighting the importance of using chemically informed atmospheric boundary conditions when available.

Warps are responsible for various global disc phenomena and observational signatures and have mostly been studied using global hydrodynamical simulations. However, their role in planet formation and affecting dust instabilities is best studied in a local frame. I will present our recent efforts in modelling dusty warps in a local shearing box and show that warps can cause dust instabilities that lead to fast dust concentrations, much faster than the streaming instability. I will also show analytical and modelling efforts to investigate the effects of dust on the parametric instability.

The Class I protostellar stage is a critical phase early in stellar evolution, where a rotating disk of gas and dust is formed, setting the chemical budget for the formation of planets. However, unlike the slightly older Class II disks, Class I protostars are deeply embedded in their natal envelopes. With the coverage, sensitivity and spectral resolution of the JWST, we are now capable of characterising their warm inner (<10au) planet-forming regions.
We present new JWST MIRI-MRS spectra of four Class I protostars in the Ophiuchus and Taurus star-forming regions. These spectra, alongside archival spectra, host a large variety of molecular emission and absorption features. Previous CRIRES observations of resolved CO emission for these targets revealed multiple components of emission
with various origins, including disks, outflows and envelopes. By comparing the features observed in MIRI-MRS spectra with these resolved CO line profiles, we aim to disentangle H$_2$O and hydrocarbon emission components from the disk and envelope analogous to those observed in CO. We then apply LTE slab-models to determine the column densities, excitation temperatures and emitting radii for H$_2$O, CO$_2$, OH, HCN and C$_2$H$_2$.
We will show how we can use the line-broadening of emission in the MIRI-MRS spectra to locate the emission, which molecules are associated with disks or outflows in our sample, and the range of excitation conditions present in each component.
Our new observations of Class I disks targeted with JWST-MIRI allow, for the first time, a systematic study of the molecular composition of the disk at the onset of planet formation.

Massive stars are fundamental drivers of cosmic evolution, shaping the interstellar medium, enriching galaxies with heavy elements, and producing compact remnants. A large fraction reside in binary or higher-order multiple systems, with most undergoing interaction during their lifetimes, profoundly altering their evolution and final outcomes. Understanding the physics of binary interaction is therefore essential to interpreting massive-star populations and their feedback properties. Classical OBe stars, rapidly rotating O- and B-type stars with emission-line spectra, have been proposed to be binary-interaction products. If so, they would serve as key probes of past mass transfer, providing crucial constraints on binary interaction physics. Yet, large-scale observational multiplicity studies of OBe stars are scarce.

The Binarity at LOw Metallicity (BLOeM) survey addresses this gap by providing homogeneous multi-epoch spectroscopy of a large sample of massive stars in the Small Magellanic Cloud, including approximately 100 OBe stars. With 25 radial-velocity epochs per star, we are able to detect companions across a broad parameter space and derive robust orbital solutions. I will present the measured orbits of the detected systems, assess the probable nature of their companions, and quantify observational biases to infer intrinsic multiplicity properties. By comparing the multiplicity statistics of OBe stars to their non-emission counterparts within BLOeM, as well as to Galactic samples, we probe whether OBe stars exhibit signatures expected for post-interaction systems.

Merging galaxy clusters host Megaparsec-scale diffuse radio emission that traces re-accelerated cosmic ray electrons in the intracluster medium. Recent observations report a growing number of enigmatic radio filaments connected to the lobes of cluster radio galaxies, which may transport and preserve relativistic electrons and thereby seed diffuse cluster-scale radio sources. Resolving these filaments and measuring their spectra requires ≲1arcsecond resolution at low radio frequencies, achievable only with very-long baseline interferometry (VLBI).

At frequencies below 100 MHz, however, severe ionospheric systematic effects have so far limited VLBI observations to a few extremely bright and compact sources. 
In this talk, I present the first-ever wide-field VLBI image obtained at these ultra-low frequencies, enabled by a novel calibration strategy. An 8h LOFAR LBA VLBI observation of the Abell 2255 cluster reaches a noise level of 650 µJy/beam at 0.9''x0.5'' resolution in the 40-60 MHz band over four square-degrees, with direction-dependent calibration using ten in-field calibrators.

These data demonstrate the feasibility of sub-arcsecond imaging at tens of MHz and open a new observational window for studying the origin and transport of cosmic ray electrons in clusters.  I will showcase their scientific potential at the example of the Abell 2255 cluster.

NICER has enabled mass–radius inferences for pulsars using pulse profile modeling (PPM), providing constraints on the equation of state (EOS) of cold, dense matter. To date, PPM and EOS inference have been carried out as two separate steps, with the former using EOS-agnostic priors. This approach has several drawbacks. Ideally, one would perform a fully hierarchical Bayesian inference where the pulse profile and EOS model parameters are jointly fit, but implementing such a framework is complex and computationally demanding.

I present an intermediate solution introducing an EOS-informed prior on mass-radius into the existing PPM pipeline using normalizing flows. This approach both tightens constraints on neutron star parameters while reducing computational costs and requiring minimal additional implementation effort. I will show results for two pulsars, PSR J0740+6620 and PSR J0437-4715, and with two EOS model families: a model based on the speed of sound inside the neutron star interior (CS) and a piecewise-polytropic (PP) model. Both EOS models implement constraints from chiral effective field theory calculations of dense matter.

Since the launch of the X-ray satellite Einstein Probe (EP) in 2024, we have finally been able to constrain the origins of several fast X-ray transients (FXTs). Astrophysical transients are known across, and beyond, the whole electromagnetic spectrum, including gamma-ray bursts (GRBs) and gravitational waves. But for long our knowledge on the progenitors of FXTs remained poor. Now that we are able to do rapid localization and follow-up, it has been revealed that many FXTs originate from the collapse of massive stars, and produce type Ic broad-lined supernovae (Ic-BL SNe), similar to those associated with long duration GRBs. Despite the emerging unifying picture, the detailed properties of the bursts differ. This indicates that there are multiple physical processes at play such as central engine activity and interactions with the surrounding medium.
Studying these FXTs not only helps us to understand their progenitors, but they are also highly important for exploring the early universe and Ic-BL SNe therein. At redshifts $z>1$, SNe are very challenging to detect from the ground in optical or near-infrared light. The high energy X-ray and gamma-ray emission is, however, far more easily observable and precedes the SN by days to weeks. FXTs therefore provide an early warning for discovering distant Ic-BL SNe with space telescopes such as Hubble and James Webb. Comparing these distant SNe to nearby ones, enables us to study the evolution in SN properties across cosmic time.
In this talk, I will present an analysis of the differences and similarities between FXTs associated with Ic-BL SNe. Additionally, I will highlight my recent research that let to the detection of the furthest spectroscopically confirmed GRB-SN to date, SN 2024aihh related to the EP-discovered FXT EP240801a.

In the past decade, black holes evolved from a theoretical prediction by General Relativity to actually observable objects. In particular, accretion and outflow of plasma leave key signatures across the electromagnetic spectrum, from the Event Horizon Telescope radio observations to X- and γ-rays, from the shadow size to the shape of the spectral energy distribution (SED). These signatures allow to test gravity because extended theories typically predict the presence of black hole mimickers, i.e., objects of similar compactness but without an event horizon.

In this talk, based on state-of-the-art GRMHD simulations, I will contrast Sgr A observations with the multiwavelength appearance of compact objects predicted by Quadratic Gravity, the unique extension of General Relativity to capture first-order manifestations of quantum gravity. Constraining the allowed parameter range of black hole mimickers implies identifying the viable parameter range of quantum-gravity theories. Indeed, our simulations of accretion and outflow attribute some of these black hole mimickers with properties incompatible with multiwavelength observations of Sgr A, e.g., the absence of a central brightness depression (“shadow”) for EHT observations and a strong X-ray flux exceeding the observed SED. This enables pioneering multiwavelength tests of gravity.

We present the development of a resistive-MHD (RMHD) module within the ideal-GRMHD code GRaM-X. GRaM-X (General Relativistic accelerated Magnetohydrodynamics on AMReX) is a new, GPU-accelerated, dynamical-spacetime ideal-GRMHD code that extends the capabilities of the Einstein Toolkit to GPU-based exascale platforms. It features three-dimensional adaptive mesh refinement (AMR) on GPUs through the CarpetX AMR driver.
In this work, we have developed a Maxwell solver that evolves the electric and magnetic fields independently. Coupling this solver with the hydrodynamic equations yields a complete resistive GRMHD code. Resistive Maxwell's equations are stiff, and we use a second-order implicit-explicit Runge–Kutta scheme for stable numerical evolution. We validate the accuracy of our implementation through a series of tests in both static and dynamical spacetimes, including 1D magnetohydrodynamic shock tubes, the 2D cylindrical explosion, and the oscillations of a 3D Tolman-Oppenheimer-Volkoff star. We then apply the GRRMHD code to simulations of neutron star mergers and core-collapse supernovae (CCSNe). In particular, we investigate the role of finite resistivity in these systems, examining its impact on magnetic-field amplification, jet formation, and jet strength in CCSN models.

Ultraluminous X-ray sources (ULXs) can be considered for the most part an extreme version of X-ray binaries accreting at super-Eddington accretion rates. The most extreme manifestation of this process, other than their abnormally bright X-ray luminosities ($L_\mathrm{X} \gtrsim 10^{39}$ erg/s) occurs in the form of hundred-parsec nebulae of ionized gas surrounding them, offering a nearby opportunity to understand the impact of super-Eddington accretion on its environment. In particular, the presence of nebulae photo-ionized by the extreme-UV (EUV)/X-ray photon field produced in the accretion disk offers clues about the bolometric flux emanating from super-Eddington disks, which are believed to emit highly anisotropically. However, direct evidence for this remains elusive.

Here I will present Integral-Field Unit optical observations with the Multi-Unit Spectroscopic Explorer (MUSE) of the famous ULX NGC 5408 X–1, which powers a $\sim$30pc nebula bright in several high-ionization lines such as HeII $\lambda$ 4686. While the nebula was known before, it is the first time we have spatially-resolved spectral information. Moreover, the low metallicity of the galaxy together with the presence of this bright ($\sim$10$^{40}$ erg/s) ULX makes it an ideal testbed for the so-called “nebular HeII $\lambda4686$ problem”: explaining the puzzling presence of high-excitation nebular lines in metal-poor, star-forming galaxies. I will discuss how from these observables and constraints on the multi-wavelength emission from the accretion disk along the line of sight we can infer the true radiative output from this canonical ULX and how, these observations disfavour ULXs as the engines behind the high-excitation lines observed in metal-poor star-forming galaxies.

Intro: Katie Mulrey (2 minutes)

Keynote speaker: Marion Mulder (30 minutes)

Title: “Beyond AI - Equity & inclusion in the current political situation”
Abstract: When looking at equity & inclusion in the current (political) situation, AI is one topic that clearly comes to mind. Marion Mulder has been speaking about inclusion through a technology lens for many years and will guide us through the intersection of Artificial Intelligence, gender, ethics, and conscious innovation for an inclusive future. What’s already possible with AI today? How are Equity & including and AI connected? (More than you might think at first glance.) And as an organisation, how can you balance the use of emerging technology with its impact on people and society?
In this keynote Marion will combine her personal experience with her expertise on both Digital Technology & AI and her background in DEI as former co-founder and board member of the Workplace Pride Foundation. She will share insights in the challenges, causes, as well as potential solutions.
The future is here, what do you want it to be?

Interactive Discussion (30 minutes): If you want to bring your whole self to work, what is hindering and helping in your daily work? (30 minutes)

Dr. Ella Bosch - Making space for different ways to be in science - Recognition & Rewards at NWO - (30 minutes)

Most of the visible matter in the universe exists as highly ionized plasmas, consisting of highly charged ions (HCIs). Due to their high effective nuclear charge, HCIs strongly emit radiation in the X-ray regime and can be observed with X-ray satellites, such as XRISM.
To study these ions in a laboratory setting and establish spectral benchmarks that meet the accuracy requirements of XRISM and other future X-ray observatories, such as NewAthena, we combined an electron-beam ion trap (EBIT) from MPIK with a state-of-the-art X-ray spectrometer based on an array of transition-edge sensors (TES) from SRON to perform high-precision spectroscopy.
The ions are produced and trapped in the EBIT while the TES-array observes the light they emit after electron-ion and ion-neutral interaction with a high resolution between 2eV and 4eV over a wide spectral bandwidth from 300eV to 13keV with minimal background signal.
To facilitate the precision of the detector, we calibrate it using well-known spectral lines from the simplest HCIs, H-like and He-like ions. To ensure stability of the detector response over time and maintain the validity of our calibration, we implemented a novel high-flux solid target X-ray source, providing fiducial lines for drift correction and as a secondary calibration standard.
Using this calibration and stability we investigated several systems of high astrophysical relevance, such as the K-shell emissions of Si,S,Cl,Ar,Fe and Ni, while operating almost continuously since June 2024.
In this contribution we describe our setup, the calibration campaign and give an overview of our measurements, exploring the different atomic processes relevant for X-ray astronomy we observe under controlled conditions.

The Cherenkov Telescope Array Observatory (CTAO) will be the next-generation ground-based facility for very-high-energy gamma-ray astronomy. In contrast to space-based instruments, ground-based gamma-ray observatories detect the brief flashes of Cherenkov light produced when high-energy gamma rays interact with the Earth’s atmosphere, generating particle cascades. This technique enables the study of the most energetic astrophysical sources at TeV and multi-TeV energies, extending toward the highest photon energies currently accessible from the ground.

Within CTAO, the Small-Sized Telescopes (SSTs) are designed to explore the highest-energy regime, where large collection areas and distributed arrays are required. The SST array will operate at the southern CTAO site in the Atacama Desert in Chile and will form a key component of the observatory’s sensitivity above 1 TeV.

This contribution presents the current status of the SST project, including recent system tests and integration activities, and outlines Dutch involvement in camera development, calibration, hardware integration, and control software. An overview of ground-based gamma-ray detection techniques will also be provided to place the SST within the broader context of high-energy astrophysics

This will be a talk in two parts.

In the first part I will given an overview of the European Southern Observatory, its capabilities (VLT, ALMA, VLTI, La Sila) and current developments, including the construction of the Extremely Large Telescope where The Netherlands plays an important role, among others through the METIS, Micado and MOSAIC instruments.

In the second part I will give an overview of the Time Domain Telescope, an initiative in the context of ESO's Broadening Horizons program to identify the next big project, in the 2040s, after the ELT. The Time Domain Telescope (TDT) is envisioned to be a fully flexible spectroscopic optical-infrared facility consisting of 100+, individually steerable, unit telescope of each ~2 meter diameter, which provide fully AO-corrected image quality at the 0.1" level in the optical, and which are coupled by fibers to a smaller set of spectrographs at low, medium and high resolution. Users will have the freedom to schedule a single unit telescope, multiple unit telescopes or the full array for their targets, which specifically include time-critical observations of transients (GW sources, GRBs, Supernovae, XC-ray transients), eclipsing systems, and/or variables, but can also be extremely faint steady sources. With its AO-assisted spatial resolution the TDT, when equipped with 100 units of 2 meters, obtains the equivalent sensitivity in the background-limited regime of a monolithic 200m telescope operating in natural seeing (1"). "The Time Domain Telescope: spectra when you need them. Anywhere, anytime."

Current high-contrast imaging instruments are limited by wavefront errors originating from non-common path aberrations due, for example, to manufacturing errors in the optics and temperature drifts in the system. These create quasi-static speckles in the final science image that are difficult to distinguish from companions. The Self-Coherent Camera (SCC) exploits the light incoherence between the star and its companion to sense the stellar speckle field on the focal plane. The starlight that hits the coronagraph focal plane mask is diffracted outside the Lyot stop and is spatially filtered by a pinhole to create a reference beam. The reference beam and the leaked starlight are recombined on the science plane, creating interference fringes that do not affect the companion. We have designed and manufactured the coronagraphic focal plane mask in-house at Leiden University with Nanoscribe, a micro-3D-printer that uses two-photon polymerization to achieve sub-micron precision in height and print smooth structures.

We present preliminary results of the first on-sky closed-loop demonstration of the Fast Atmospheric SCC Technique (FAST), a focal plane wavefront sensing and control technique using the SCC. This was performed with MagAO-X, the extreme adaptive optics instrument for the 6.5-meter Magellan Clay telescope at Las Campanas Observatory. The FAST can also be used in post-processing as a differential imaging technique to further enhance the contrast.

NOVA’s instrumentation program is driven by scientific ambition: the need for access to specific data shapes our participation in major international projects. With a strong focus on ESO facilities, NOVA aims both to contribute to future instruments and to sustain and develop key technical expertise within its instrumentation groups.

As ESO prepares for the post-2030 landscape through the VLT Beyond 2030 initiative and the Expanding Horizons program, new opportunities for future instrument development are emerging. I will report on recent discussions at the VLT Beyond 2030 conference and outline ESO’s Expanding Horizons program, highlighting the concept studies in which we are currently involved. These developments present important strategic choices for the Dutch astronomical community.

As these opportunities take shape, prioritization becomes increasingly important. We must converge on a focused set of instrument ambitions that best serve the scientific goals of our community. The Strategic Plan (update) outlines these opportunities and possible directions, which can materialize in different ways. This presentation contributes to an ongoing process of informing the community about these developments. NOVA’s priorities are ultimately shaped by the scientific needs of the community, in combination with the available resource, making continued dialogue essential to converge on the instruments that will shape the scientific capabilities and technological expertise of the Dutch astronomical community in the coming decades.

After more than 30 years of talking, the construction of the Square Kilometre Array (SKA) is now well underway. In this talk, I will give a update on construction, science verification, and what this stage of project development means for the Dutch astronomy community. In particular, I will focus on the establishment of our own regional centre, and its expected role in the community. NAC is the ideal forum to present this information considering the community investment in the project and the current important developmental stage the SKA.

iDaVIE (immersive Data Visualisation Interactive Explorer) is a software tool developed at IDIA (Institute for Data Intensive Astronomy) in Cape Town (https://idavie.readthedocs.io/en/v1.1/). It allows viewing, manipulation and analysis of 3D data in a Virtual Reality setting where one is immersed in the 3D data environment.

There are two versions of iDaVIE. iDAVIE-v allows viewing of 3D spectral line data cubes, such as HI data cubes, ALMA data cubes for molecular lines, or optical data cubes produced by IFU systems such as WEAVE on the WHT or MUSE on the VLT. iDaVIE-p allows viewing of catalogues or tables. These could be redshift survey catalogues, cosmological simulations, or any table containing at least three columns.

I will give an overview of the capabilities of both versions of iDaVIE and demonstrate the power of VR viewing of 3D or higher dimensional data and briefly summarise the hardware required to run iDaVIE.

The outflows of massive stars significantly affect their stellar evolution and surroundings. The mass-loss rates of these stars is thus essential to constrain from their stellar spectra. However, this requires the detailed spectroscopic analysis of large samples of stars. Precisely modelling the wind and atmospheres of massive stars is computationally very expensive, which severely limits the sample of stars that can be analysed. By replacing a 1D spectral atmosphere code with a neural network as a surrogate model, generating synthetic spectra becomes several thousand times faster, allowing the use of previously computationally unfeasible but statistically more robust sampling algorithms such as using Markov Chain Monte Carlo or simulation-based inference. In this talk I'll discuss our recent development of a neural network emulator for the radiative transfer code FASTWIND, and discuss how well neural networks perform when predicting stellar spectra of LMC O-stars. I will give insights into how their performance compares to using stellar atmosphere codes when inferring the parameters of observed stellar spectra. I will also compare the already established optimization methods to previously inaccessible sampling methods.

We present a new method for fast inference of pulsar emission and interstellar medium (ISM) parameters directly from frequency-resolved pulse profiles. Accurate parameter estimation is challenging due to strong degeneracies, and classical Bayesian likelihood-based fitting becomes computationally expensive for high-dimensional parameter spaces.

We build a physically motivated simulator that generates frequency-resolved pulses. The model includes multi-component profiles, spectral evolution of amplitude and width, dispersion measure, and scattering.
Using simulation-based inference (SBI) we are able to recover posterior distributions of dispersion measures and scattering parameters, without explicit likelihood evaluation.

Once trained, SBI enables faster inference with reduced computational costs.
This technique may be particularly useful for pulsar timing arrays, gravitational-wave astronomy and fast radio burst studies. In these studies Bayesian models are common and high dimensional and vast amounts of data are present, making efficient posterior estimation important.

With the boom of applications of deep neural networks in (astronomical) research, we have grown an urgent need to crack open our own black boxes, lest our reviewers start asking us difficult questions we cannot answer. Enter the field of "explainable AI" (XAI), in which methods to solve this issue are developed and studied. I will give a short introduction into XAI in general, and present our specific method called Distance Explainer, which "explains" which parts of your data actually drive (dis)similarity in a learned embedding space. I'm curious whether you are working on something where this could be useful. If so, let's talk.

In a 2021 study on Dutch traditional media, “plasma physics” was found to be the lowest represented topic amongst news articles discussing physics, at only 0.4%[1]. In contrast, “astronomy and astrophysics” (a topic overlapping with plasma) had over 100 times more representation with 44.4%. Poor science communication representation has led the general public to be unaware of technological plasmas: in a small informal survey conducted by the authors (n=15) asking “Waaraan denkt u als u plasma hoort?”, only one respondent's answer was somewhat related to ionised matter, associating plasma with science fiction energy.

To improve society adopting plasma technology[2,3], the authors seek to learn how to improve communicating research from astronomers to then, , promote dialogue and produce interactive shows and exhibitions for the public with the astronomers input and recommendations.

[1] Kristensen, S.W. et al. J.Sci.Com. 20(07)(2021)A02.
[2] Maryikan, D. et al. J.Info.Sci. (2023) 01655515231191177
[3] Gupta, N. et al. Public Understanding Sci. 21.7(2012):782-795.

The three mobile planetariums operated by the Netherlands Research School for Astronomy (NOVA) are a highly effective and successful way of introducing astronomy to school students in a live and interactive way. Our mission is to let every school kid experience the thrill of discovery once in their school career. Since the start of the project, it has reached over 600,000 children. However, there are some ‘blank spots’ on the map of visited schools we update every year since 2010. The underserved communities are certain neighborhoods in the big cities and small schools in the countryside. With an NWA-grant from the Dutch organization for science funding NWO, we are running a project with a societal partner (an educational organization) to make our mobile planetarium project more inclusive. We present the preliminary results.

The Dutch astronomy community is internationally recognized for its scientific excellence and strong collaboration across institutes. Sustaining this strength requires continued coordination, visibility, and accessible channels for collaboration.

In this presentation, I will briefly introduce my relatively new role as NOVA’s Research and Community Coordinator and outline ongoing efforts to support alignment and exchange across the Netherlands. In the short term, these efforts focus on improving visibility and connection within the community; in the longer term, they contribute to building a resilient, well-organized, and well-funded national network.

A central step in this process is the launch of our new community website and portal. Designed as a shared digital home for Dutch astronomy, the platform enables researchers to find information more easily, connect across institutes, and identify opportunities for collaboration. By centralizing communication and lowering practical barriers, it strengthens our sense of community and supports a cohesive and engaged network. I will introduce the platform and discuss how it can further connect and support us all.

Over the past few decades, social media has fundamentally transformed the global communication landscape. Videos have become an increasingly important form of communication, from short-form to long-form content on platforms like YouTube. Especially for smaller institutions and outreach offices, this requires a systematic adaptation of their communication approach. The central resource of the current media landscape is the viewer’s attention. Producing videos that effectively educate and inform the audience about current astronomy research, whilst being competitive in the user’s feeds, is a challenging balance between scientific accuracy and platform optimisation.
In this talk, I present my science communication research and experiences gained at the NOVA Information Center on astronomy video production. I will discuss how different choices in narration style, video format, and platform affect audience engagement. This research is currently being conducted by producing videos with two deliberately distinct narration styles and applying a mixed-method analysis of video analytics, channel performance and comments online.
Furthermore, I will share practical insights and strategies, such as workflows and platform-specific tips, on how communication offices can maintain effective video production with limited resources.

To understand how galaxies form and evolve, we must first contend with dust. Though it makes up only a tiny fraction of a galaxy's mass, interstellar dust acts as a cosmic veil, absorbing starlight and re-emitting it at longer wavelengths. This process, known as attenuation, significantly alters the spectra we observe with instruments like JWST. Until now, large-volume cosmological simulations have struggled to trace dust evolution in a self-consistent manner due to high computational costs.

In this talk, I will present results from COLIBRE, a new suite of state-of-the-art cosmological simulations which for the first time incorporate a multi-grain live dust model. By pairing galaxies from COLIBRE with the radiative transfer code SKIRT, we obtain mock spectra that allow us to study the evolution of dust attenuation through cosmic time. After validating our model against current observations, we use it to disentangle the two primary drivers of the attenuation curve: dust-star geometry and grain composition. These results provide a critical framework for interpreting the next generation of high-redshift observations.

The sizes of galactic disks are known to depend on stellar mass and redshift, with galaxies of a given mass expected to be more compact at higher redshifts. However, observational studies have uncovered disk galaxies at z~3 that have sizes significantly larger than expected from the mass-size relation. Notably, these ‘giant disks’ are preferentially found in proto-clusters, suggesting that over-dense regions facilitate the early formation of such galaxies. In this poster, we present additional promising photometric candidates of giant disks in the early universe (3$<$z$<$7) using JWST NIRCam imaging (F444W) of the contiguous COSMOS field. We also measured the local environment of the galaxies using the CosmicWeb pipeline and n$^{\text{th}}$ nearest neighbour estimates. The environmental density estimates are then used to examine the role of local environments in enabling the formation and survival of such disks.

In order to understand star-forming processes in dusty star-forming galaxies, observations of dense gas tracers, such as HCN, HCO+ and HNC, are required to link existing studies of their molecular gas, typically traced via CO or [CII], and obscured star formation, traced via the dust continuum. Previous studies suggest that high-z DSFGs could be surprisingly lacking in dense gas for sources with such significantly elevated star-forming efficiencies. To investigate this with a wider robust sample, we present a comprehensive ALMA Band 1 survey of nine strongly lensed galaxies from the SPT sample that lie between z=2.5 and z=3.5. Deep observations of the J_upp=2 transitions of HCN, HCO+ and HNC lines allow us to examine HCN/FIR and HCN/CO ratios, look for further molecular lines in a stacked spectrum and attempt to link these to star-formation models. Access to dense gas tracers through ALMA band 1 allow us to make a robust determination of dense gas content and star-forming efficiency in DSFGs, bridging molecular gas measurements and obscured star formation at high redshift.

Galaxy mergers represent a critical and complex phase in galaxy evolution, often triggering nuclear activity and intense episodes of central star formation that can profoundly influence the subsequent evolution of the system. In this talk, I present new insights into the impact of active galactic nucleus (AGN) feedback on the multi-phase interstellar medium (ISM) in the central region ($\sim7-14^{\prime\prime}\sim100-200$ pc) of Centaurus A, the nearest active radio galaxy ($D_{\rm L} = 3.5$ Mpc).

This study is part of the Guaranteed Time Observations (GTO) program Mid-Infrared Characterization of Nearby Iconic Galaxy Centers (MICONIC) of the MIRI European Consortium. Leveraging the high spectral resolving power of JWST/MIRI-MRS across the $4.9-27.9\,\mu$m wavelength range, we obtained unprecedentedly rich mid-infrared spectra of the nuclear environment at sub-arcsecond angular resolution ($1^{\prime\prime}\sim17$ pc).
These observations reveal clear signatures of shock-excited gas and strong energetic processing driven by the AGN.

We identify and model emission from ionized gas (Alonso-Herrero et al. 2025), rotational transitions of molecular hydrogen (Evangelista et al. 2026), and polycyclic aromatic hydrocarbon (PAH) features (Pantoni et al. 2026). By combining diagnostic line ratios, gas kinematics, and detailed spectral line-profile fitting, we characterise the physical conditions of the ISM and assess the relative contributions of shocks and AGN radiation in shaping the circum-nuclear medium.

Active galactic nuclei (AGNs) influence their host galaxies through powerful winds that drive large-scale outflows, regulating star formation by heating, removing, or compressing the interstellar medium (ISM). Despite their importance for galaxy–supermassive black hole co-evolution, the impact of AGN-driven feedback on the surrounding molecular gas reservoir remains poorly understood. In this talk, we present a first kinematics study of outflowing molecular gas in a typical circumnuclear disk (CND) using a 3D radiative transfer code coupled with kinematic models. We explore both a fully outflowing disk and a partially outflowing disk in which the outflow velocity depends inversely on gas density. For the fully outflowing CND, we find that increasing outflow velocity, increasing outflow inclination, and decreasing disk compactness all lead to more complex synthetic line profiles, with additional strong effects on the line-of-sight velocity centroids and component widths. In the partially outflowing case, the line profile structure similarly depends on the density–velocity relation. This work represents a first step toward a kinematics-based radiative transfer framework for extra-galactic circumnuclear environments, with future works including inner AGN structures such as the torus and combining radiative transfer with chemical modeling.

We present the discovery of an extraordinary overdensity around a source of the ALMA Large Program REBELS at z=7.35, among the most extreme proto-clusters known beyond z>7. Within just 21″×21″ (Δz<0.01), we identify 5 sources in [OIII]5007 with NIRCam/Grism observations, also showing in ALMA data as 4 of the brightest [CII] 158μm emission known at z>7. The properties of these galaxies show accelerated evolution in this overdense environment: one NIRCam dark source, a galaxy undergoing a major merger and high metallicities. These galaxies sit above the star-forming main sequence, with stellar masses and SFRs both ~1 dex higher than members of other known proto-clusters at comparable redshifts. These suggest elevated star formation linked to dynamical interactions within this dense environment. We compare this structure to simulations to identify analogous systems and use TNG300 results to trace their probable evolution to z=0, testing whether these most massive early structures effectively seed today's most massive clusters. This system offers a rare laboratory to study how overdense environments drive accelerated, bursty star formation and rapid dust enrichment at z>7, and allow us to understand more how the first large-scale structures in our Universe formed.

We investigate the impact of stellar cluster initial conditions on the dynamical evolution of planetary systems. Two configurations are considered; a sub-virial fractal distribution and a virialised Plummer distribution. Both models are initialised with a virial radius of $0.5$pc, $150$ stars and $~145$ planetary systems. Five realisations of each configuration are performed with identical stellar and planetary populations, including a debris disk but omitting gas. Clusters are integrated until $30$ Myr using a novel hybrid multi-scale N-body code that resolves planetary systems in cluster environments self-consistently.

The sub-virial fractal cluster exhibits richer dynamics, with asteroids and planets more frequently acquiring high eccentricities and inclinations, along with a larger fraction of captured and rogue objects. Additionally, this cluster configuration has its extreme trans-Neptunian object and Sednoid analogues occupy regions of phase-space in semi-major axis, eccentricity and inclination that are commonly frequented by captured asteroids. Although the virialised Plummer model can produce such objects, by being less dynamically active, the vast majority of asteroids occupying these regions are native rather than captured. Lastly, neither model efficiently forms an Oort Cloud, indicating that Oort Cloud assembly is strongly suppressed in both dynamically active and quiescent cluster.

These results demonstrate that the bodies on relatively wide orbits (a\sim10^{2} au) retain measurable imprints of their birth cluster morphology. These results imply that observed minor-body populations and interstellar object rates may provide constraints on the Sun’s natal cluster morphology. Given that the Sun is thought to have formed in a more massive cluster ($\gtrsim10^{3}$ stars), ongoing work explores how denser and more massive environments further sculpt debris disk evolution.

YSES 1 b is a directly imaged young substellar companion on a wide orbit of 160 AU, making it an interesting challenge for formation theories. Initial photometric observations with SPHERE and NACO from Y to M band suggested physical parameters of Teff=1700 K, R=3 R_J and M=14 M_J. Here, we present new observations in the r’, i’ and z’ band using the MagAO-X instrument and revisit the modelling of YSES 1 b based on the combined MagAO-X, SPHERE and NACO data. In addition, we update the forward model by including the effect of possible dust extinction from the circumplanetary disk (CPD) which was recently confirmed with JWST. The newly derived parameters result in a higher Teff of 2800 K and a more physically expected radius of 1.6 R_J. The mass increases to 26 or 42 M_J, depending on the age used for the system. This result suggests that YSES 1 b resides more in the brown dwarf realm rather than the planetary regime.

The interpretation of exoplanet spectra obtained with JWST typically assumes that observed atmospheres are in steady state. In this work, we challenge that assumption by demonstrating that stellar flares can induce rapid and long-lasting changes in atmospheric composition that directly impact observables. We model the effects of recurrent stellar flaring on metal-rich exoplanet atmospheres using time-dependent photochemistry and radiative transfer. We find that flare activity drives strong variability in key molecules such as SO₂, CO₂, CH₄, and H₂O, producing spectral changes at the tens to hundreds of parts-per-million level, well within JWST sensitivity. Extreme flares can temporarily suppress molecular features, while cumulative flaring leads to persistent compositional shifts on decadal timescales. These results imply that JWST spectra do not necessarily probe a planet’s equilibrium state, but rather a snapshot conditioned on recent stellar activity. Atmospheric retrievals must therefore account for temporal variability to avoid biased inferences of composition and climate, especially for planets orbiting active stars.

Energetic particle events occur when charged particles are accelerated to near-relativistic energies during stellar flares or coronal mass ejections, and they help shape planetary atmospheres through erosion and chemistry. Traditional stellar activity probes, such as optical and soft X-ray flares, trace thermal plasma and are effectively blind to escaping relativistic particle beams. Based on solar studies, we know that a characteristic radio burst (called a Type III burst) provides an unambiguous signature of energetic electrons propagating along open magnetic field lines. However, there has not been a detection of an extrasolar Type III burst. In this talk, I will present the first extrasolar analogue of a solar Type III burst, which signals the presence of escaping energetic particles. I will present estimates of the incidence of energetic particle events on M dwarfs compared to solar values, together with the approximate particle energy flux in the habitable zones of M dwarfs. This detection demonstrates that stellar energetic particle events can now be identified through radio observations, opening a direct observational pathway to their impact on exoplanetary environments.

H$\alpha$ emission is abundant in ultracool dwarfs (UCD), but its origin is unclear. While it may stem from residual star-like, chromospheric emission, it may also be attributed to planet-like magnetospheric emission akin to Jupiter's aurora. A way to resolve this issue is to measure the spatial distribution of H$\alpha$ emission on the UCD. Chromospheric emission would appear distributed in spots, and/or spread out across the entire surface. In contrast, auroral emission would manifest as a ring structure centered on the magnetic axis, produced by particles precipitating along a largely dipolar magnetosphere.

In this talk, I will present the first application of this method using time series of high-resolution spectra of LSR J1835, a young nearby brown dwarf. I will show evidence that the H$\alpha$ emission from LSR J1835 emanates from a combination of an oblique ring with two high-latitude spots, suggesting that the UCD produces a chimera: a residual stellar chromosphere, embedded in a largely dipolar magnetosphere powering the auroral ring. This is consistent with the broader observational record of LSR J1835, which shows both planet-like features like radiation belts and coherent emission at radio frequencies, and star-like flares in its optical photometry.

Finally, I will demonstrate that discriminating different emission structures through forward modeling and Bayesian analysis is possible, but requires high signal-to-noise, high-resolution spectra that place LSR J1835 as the only viable target. However, looking ahead, E-ELT/ANDES will extend our reach to spectral types as late as L3, opening a new window into the magnetic and atmospheric physics of UCDs, and the space weather of planets around them.

We present the first large-scale statistical analysis of an extensive catalogue of interplanetary Type III solar radio bursts compiled through human participation. The catalogue is based on Radio and Plasma Waves (RPW) observations from Solar Orbiter, collected through the citizen-science campaign Solar Radio Burst Tracker hosted on Zooniverse, with contributions from 867 volunteers between February 2020 and March 2025.
The final catalogue contains 15,934 Type III bursts, which were systematically compared with solar activity phenomena. We find clear correlations with solar flares, while short-scale deviations indicate that Type III bursts are not solely determined by flare energetics but are also strongly influenced by coronal and interplanetary plasma conditions governing electron-beam propagation and wave–particle interactions. Furthermore, burst characteristics show a measurable dependence on flare energy class.
Analysis of peak flux across 23 frequencies reveals power-law behavior with an average slope of −1.57 ± 0.01, steepening toward higher frequencies. At still higher frequencies, the slopes plateau around −1.7 to −1.8, resembling scaling behavior consistent with self-organized criticality. Burst occurrence peaks at 1–2 MHz, suggesting particularly efficient electron-beam transport and beam–plasma interaction in this frequency range.
Frequency drift rates derived for 13,074 bursts follow the empirical relation
df/dt = −0.002 f¹·³⁷, differing from previously reported relations over other frequency ranges. Notably, the drift-rate trend shows an enhancement near 1–2 MHz, coincident with the occurrence maximum, likely reflecting the influence of plasma density structure in the inner heliosphere.
This human-validated, large-scale catalogue provides a robust statistical resource for Type III burst studies, capturing solar-cycle and observational effects, extending analyses to faint and complex events, and placing new constraints on frequency-dependent flux and drift behavior. The catalogue further establishes a benchmark dataset for future automated and machine-learning detection methodologies.

Cassiopeia A (Cas A), the youngest known core-collapse supernova remnant (SNR) in the Milky Way, offers an unparalleled view of the explosions of massive stars. A >350 ks observation with XRISM has delivered an unprecedented high–spectral-resolution X-ray view of this archetypal remnant and produced the mission’s most productive dataset to date, with 5+ published papers. In this talk, I will present these latest XRISM results.

Key breakthroughs include the first X-ray detections of the odd-Z elements P, Cl, and K in any SNR. We uncover an incomplete ejecta shell in which Si- and S-rich components exhibit distinct ionization states and velocity structures. Near the projected center, we detect narrow, low-velocity emission lines likely associated with circumstellar material.

Using the new Bayesian spectral tool UltraSPEX, we present the first comprehensive microcalorimeter-based plasma mapping of an SNR. We identify clear kinematic differences between intermediate-mass (IMEs) and iron-group elements (IGEs), and a strong anti-correlation between ionization timescale and electron temperature, consistent with significant ejecta clumping (overdensities of ~10 for IGEs and up to ~100 for IMEs) and reduced historical reverse-shock velocities. Finally, we disentangle thermal and non-thermal components, showing that synchrotron emission contributes at least 47% of the 4–6 keV flux at XRISM resolution.

These results provide the most detailed spectroscopic portrait of Cas A to date.

The Square Kilometre Array (SKA) is a next-generation radio telescope currently under construction in South Africa and Australia.
Its low-frequency part (50-350 MHz), located in Australia, features nearly 60,000 antennas in a core region of about 1 km diameter.
The unprecedented antenna density allows to observe individual cosmic-ray air showers to a level of detail no other observatory can match.
Hence, we adopt the same approach as done successfully at LOFAR, which is to put about 100 small (1 m$^2$) particle detectors alongside the radio array, which are used to trigger a readout of ring buffers storing the raw digitized voltages at the antennas.

We present the expected capabilities of this instrument, especially where it surpasses predecessors such as LOFAR. This includes the important science questions in the field, related to the mass composition of cosmic rays as well as the high-energy particle interactions at energies beyond e.g. LHC energies; measuring air showers at very high precision offers an opportunity to measure these, however indirectly, by their imprint on the radio signals as they arrive at the antennas.
We also present our current status on the way to realizing this observing mode at SKA-Low, which includes significant progress in developing and building the RFI-quiet particle detector array.

Fast radio bursts (FRBs) are millisecond-duration, extragalactic radio transients of unknown origin. The FRB backend on the CHIME telescope (CHIME/FRB) is the most prolific FRB discovery machine, having detected more than 4000 unique sources of FRBs. The recent addition of three CHIME Outrigger stations across Northern America enables the precise sub-arcsecond localization of multiple FRBs per week. This in turn enables robust host galaxy identification which unlocks exciting prospects for FRB science, two of which I will discuss. Firstly, by precisely pinpointing bursts to their galactic environments, source models can be constrained since different sources tend to be linked to specific galactic environments. Secondly, it allows for FRBs to be used as probes of the material between the source and observer, since spectroscopic redshifts (distances) become accessible once a host is robustly identified. Currently, the Outriggers are capable of achieving localisation precision of approximately 50 milliarcseconds, and ongoing work aims to push this further. I will review some of the major findings of the Outriggers thus far and describe some of the work being done to further improve localization precision. This includes validating astrometric positions of VLBI calibrators (radio bright active galactic nuclei) at the low operating frequencies of CHIME/FRB (400-800 MHz), where source structure and core-shift of these AGN can introduce localisation offsets. I will also present some of our efforts to use the Outriggers to localise bursts from known repeating FRBs that have previously been localised by the European VLBI Network to (tens-of-)milliarcsecond precision, in order to validate our astrometric pipeline and search for systematic offsets.

The future of very low frequency radio astronomy lies on the Moon, where the absence of an ionosphere and terrestrial radio interference enables observations below ~30 MHz. The upcoming LuSEE-Night mission will deploy four monopole antennas on the lunar farside to measure the global signal from the Epoch of Reionization and coherent emission from exoplanets. Before scientific measurements are possible, the instrument must be calibrated in a complex and poorly understood environment. Without a metallic ground plane, the antenna response will be shaped by reflections within the lunar regolith and underlying bedrock, producing frequency-dependent ripples in the signal. Luckily, LuSEE-Night includes a dedicated calibration beacon that emits a well-characterized signal. In this talk, I show how this calibrator can be used not only for instrumental calibration but also to constrain key properties of the regolith, such as density and thickness, using Fresnel reflection coefficients and basic antenna theory. Quantifying these environmental effects is a necessary step before the science can begin.

4U 1556-60 is an X-ray binary that was discovered more than 50 years ago as a persistent X-ray source. However, very little was known about it, including fundamental properties such as its distance, whether the accreting compact object was a black hole or neutron star, and its orbital period. Recently, Gaia Data Release 3 has provided a parallax for the optical counterpart of 4U 1556-60, placing it only 700 pc away and making it one of the closest X-ray binaries known to date. Motivated by this new distance, we have re-investigated 4U 1556-60 using both old and new data, and found that this X-ray binary might be quite unusual and intriguing. Our conclusion is that 4U 1556-60 is most likely to be a very faint ultracompact neutron star X-ray binary at 700 pc. Interestingly, there appears to be residual hydrogen in the accretion disk, it has never been observed to undergo a thermonuclear burst, and furthermore it has a radio upper limit that makes it one of the weakest X-ray binary jets known to date. These results and others have provided a fresh perspective on 4U 1556-60, and motivate future follow up work to better understand its properties as a very nearby and possibly rare class of X-ray binary.

GRS 1915+105, the low mass X-ray binary with the largest accretion disk and the first microquasar observed with superluminal jets, has stayed in a high-luminosity outburst for decades since its discovery in 1992. However, in mid 2018, the source entered a new phase in which the X-rays suddenly dropped to an unprecedentedly low flux that was quickly followed by a rebrightening in the radio, breaking the phenomenological X-ray – radio correlation that links the accretion flow and jets. Multi-wavelength observations suggest that this low X-ray state is the result of a complex layer of absorbing material, whose exact nature remains unknown. Milliarcsecond-resolution radio imaging allows us to probe the jet direction and its behaviour at the base during this unprecedented phase in the lifetime of GRS 1915+105.

I will present four radio Very Long Baseline Interferometry (VLBI) epochs during this X-ray obscured phase that reveal highly variable radio behaviour, including flaring within our observations and the launch of discrete ejecta. By applying a time-dependent model fitting approach directly to the visibility data we put tight constraints on the ejecta’s speeds and ejection times, which we compare to corresponding features in the accretion flow.

Remarkably, we detect a large swing in the jet direction (up to 59° ± 2° with respect to the last VLBI observation from 2006), something that hasn't been observed in GRS 1915+105 prior to the obscured state. This makes GRS 1915+105 the only microquasar found to exhibit both precessing and fixed-direction extended jets. The presence of both jet types has implications for a recently proposed jet paradigm, distinguishing precessing, slow jets and fixed, fast jets locked onto the black hole spin-axis. I will discuss potential mechanisms that link this abrupt, milliarcsecond jet precession to the X-ray obscuration phase, including a ULX analogy and radiative warping.

On August 31st, 2024, the LOFAR radio telescope paused after 15 years of operations to undergo a major upgrade. In this upgrade, our lessons learned from that period are incorporated into new hardware, firmware, and software. Except for the antennas, almost everything is being replaced as we build LOFAR2.0: receiver units, digital beam formers, clock distribution, network infrastructure, the correlator, pre-processing cluster, monitor- and control software, proposal submission- and data management tools, and major data processing pipelines.

By May 2026, all Dutch stations have been fully converted, as have the first international station(s?). Commissioning of LOFAR2.0 began in 2024 as soon as the first station was converted, and is foreseen to continue until all stations are upgraded somewhere in 2027. In this contribution we first introduce LOFAR2.0's architecture and our approach to commissioning this continent-scale scientific facility. Then we will discuss the current status of commissioning, including several concrete results like station calibration, effective sensitivity, performance of the clock distribution sub-system, and initial pulsar capabilities and imaging plans.

The mechanics of binary evolution remain largely invisible other than the luminosities that reach us. However, these luminosities are the end result of a chain of interdependent feedback processes spanning the entire binary system to accrete material from a still-evolving donor star. With recent developments a clear picture of this mass transfer is now possible. Only by tackling system dynamics across evolutionary timescales can we truly understand the the evolution of close binary stars.

In this talk, I will describe in detail my novel approach to track mass transfer hydrodynamics in high-resolution 3D across system evolution. This model captures the donor envelope, wind, tidal stream, accretion disk, and X-ray feedback interacting in tandem. These regimes are collectively evolved through the new method of Time-Incremented Multiscale Evolution (TIME). This enables variable time resolution by cyclical feedback between 3D hydrodynamics and 1D binary evolution codes.

This model is capable of translating a 1D profile accounting for tidal deformations into a 3D stellar envelope while retaining hydrostatic equilibrium everywhere well away from the inner Lagrange point. This enables smooth feedback between dynamical and evolutionary codes without introducing artifacts due to model relaxation.

It is now possible to model long evolutionary timescales while fitting 3D sub-orbital timescale dynamics, in a new milestone for stellar evolution.

I will discuss my results in the context of several previously under-constrained quantities in binary interactions. I conclude that the wind Roche lobe overflow mode can persist at higher filling factors than previously thought ($f>1$). On the opposite end, I identify binary mass transfer more than 10% overflowing ($f>1.1$) to be necessarily brief ($<100$ years).

Finally, I will plot the course for future developments in binary models towards high-resolution 3D models of nuclear-timescale mass transfer in the next few years.

The large-scale structure of the Universe encodes a wealth of information about cosmology and galaxy formation. For decades, two-point correlation functions have served as a cornerstone of this effort, distilling the complex distribution of matter into powerful statistical measures. These summary statistics underpin precision constraints on the standard cosmological model and provide key insights into dark matter and dark energy.

In this talk, I will show how two-point statistics can be used as a single, powerful tool to study the Universe across a wide range of scales—from individual galaxies to massive galaxy clusters. Using data from the Hyper Suprime-Cam (HSC) survey, we map the matter distribution within these systems by constraining scaling relations that connect visible galaxies to the dark matter halos that host them, and use these results to better understand and test galaxy formation models. I will also present observational studies of the physical processes at the outer boundaries of massive X-ray galaxy clusters, where ongoing accretion and feedback influence how structures grow and evolve.

On cosmological scales, I will present results from HSC Year 3 weak-lensing analyses, focusing on key systematic effects and how they affect constraints on cosmological parameters. I will then show how cross-correlating galaxy catalogs with gravitational-wave events provides a new and independent way to measure the expansion rate of the Universe. Finally, looking ahead to the Euclid era, I will discuss how improved measurements of baryons on small scales will open a new level of precision in cosmology. Together, these studies highlight how a simple statistical measure continues to deepen our understanding of the Universe’s structure and evolution.

Water (H$_2$O) is key for habitability, but the delivery mechanism to (forming) planets is not yet well understood. The James Webb Space Telescope, especially through the MIRI instrument, can now study the planet-forming regions (inner few au) of disks around young stars. Hundreds of ro-vibrational (<10 $\mathrm{\mu}$m) and pure rotational (>10 $\mathrm{\mu}$m) transitions can probe the available H$_2$O reservoirs (cold, warm, and hot) in great detail.

It is proposed that the reservoirs can be altered by efficient radial drift or frequent accretion (out)bursts. While the latter requires detailed knowledge of the (often unknown) accretion timescales, the importance of radial drift is easier to examine, as observations with the Atacama Large Millimeter/submillimeter Array have revealed substructures (or pressure traps) in many disks that may impede the drift.

In this talk, I will present the analysis of the H$_2$O reservoirs in a sample of 24 T-Tauri disks that are part of the MIRI Mid-Infrared Disks Survey (MINDS), a JWST Cycle 1 GTO program. The sample comprises disks with various characteristics: from very small disks to large ones and disks with no apparent structures to those that are highly structured or have large cavities as seen with ALMA. This analysis provides, therefore, unique insights into the different H$_2$O reservoirs and the role of radial drift.

Fast radio bursts (FRBs) are among the most mysterious and exciting phenomena in modern astrophysics. These are extremely energetic bursts originating from extragalactic distances, providing unique probes of the intergalactic medium and offering new ways to study the universe at cosmological scales. Despite major progress in recent years, many questions remain open about their origins, emission processes, and local environments.
To address these questions, we established the HyperFlash program, a coordinated, high-cadence FRB monitoring effort using 25-32 m class radio telescopes across Europe at Westerbork (NL), Torun (PL), Onsala (SE), Stockert (DE) and Dwingeloo (NL). Our goal is to observe the brightest and rarest FRBs.
Since 2021, we have accumulated close to 42,000 hours of observations, resulting so far in hundreds of burst detections, enabling constraints on burst energetics and local source environments.
In this talk, I will give an overview of HyperFlash’s main results, demonstrating how "small" radio telescopes can make meaningful contributions through persistent, high-cadence observing. Finally, I will present our latest technical development: the design and ongoing commissioning of a new ambient-cooled L-band receiver (ALF) for the Westerbork Synthesis Radio Telescope.

Fast Radio Bursts (FRBs) are rapidly becoming unparalleled cosmological tools: the dispersion of these millisecond-duration bursts traces the ionised material along the line of sight, while scattering and Faraday rotation encode the turbulence and magnetic field of intervening media. Nowadays, with more than a hundred FRBs localised to their host galaxies at increasing redshifts, they offer a direct way to test the cosmic baryon census, probe the growth of large-scale structure, and quantify galactic feedback at high redshifts.
The MeerTRAP project was conceived to leverage MeerKAT's high sensitivity and angular resolution to identify radio transients, finding more than ninety FRBs since 2019. When a new bright FRB is detected, 300 ms of raw voltage data are stored, which we use to localise these bursts with arcsecond precision, enabling their study at the highest time and frequency resolution.
In this talk, I will present the most distant FRB sample localised with MeerTRAP, including the first FRB beyond redshift 2. These events push the boundaries of the known FRB population into the cosmic noon, where the IGM contribution to dispersion dominates, and comparisons with cosmological predictions become particularly constraining. By combining redshift information and propagation effects with deep optical and near-infrared surveys, we can disentangle the contributions from the local environment, the IGM, and foreground galaxy halos.
Furthermore, the substantial observing time that MeerKAT dedicates to selected “deep fields” has produced multiple FRB detections along similar sightlines. This allows us to probe the large-scale structure by mapping the baryon distribution of the cosmic web in these directions.
Overall, this high-redshift FRB sample demonstrates that precise localisation and propagation properties of distant bursts can turn FRBs into unprecedented probes of galaxy evolution and cosmology.

Current and planned X-ray telescopes have imaging resolutions on the order of arcseconds or worse, which exceeds the theoretical diffraction limit by four orders of magnitude. By leveraging a compact, single-spacecraft design, X-ray Interferometry (XRI) can achieve an EHT-like spatial resolution of tens of microarcseconds.
This enormous leap in resolution allows for direct imaging of stellar coronae from tens of parsecs, resolving X-ray binaries throughout our galaxy, and tracing AGN accretion disks and supermassive black hole binaries across the visible universe. We are developing a mission concept to unlock this remarkable potential: XRIstel, the X-ray Interferometric Space Telescope. Beyond the development of advanced technologies, which I will briefly describe, realizing an X-ray interferometer necessitates a new type of science simulator that is crucial to develop a detailed science case, set mission requirements, and empower the future XRI community. This new software, which will be publicly released shortly, enables users to generate and analyze X-ray interferometric data for simulated sources conforming to the SIMPUT file format. Here, I will introduce the simulator and present initial case studies for XRIstel.

Long-period transients (LPTs) were discovered a few years ago as mysterious radio sources that produce bright pulses that repeat on periods of minutes to hours. While they have been suggested to be extremely slow magnetars or white dwarf binaries, conclusively determining their origins has been complicated by their large distances and high extinction, which make follow-up at other wavelengths nigh impossible. Furthermore, these objects have only been discovered recently, preventing multi-wavelength monitoring on the long timescales required to understand these objects simply because the time has not passed yet. However, we have recently discovered a system that bypasses all of these limitations. In this talk, I will present a new LOFAR-discovered LPT that has a well-studied optical counterpart, providing us with data going back over a decade. Combining this wealth of auxiliary data with the information gained from the radio detections, I will discuss the origins of this particular LPT and bring the field one step closer to solving the mystery of the origin of LPTs as a whole.

Understanding the Epoch of Reionisation remains one of the pivotal tasks for modern cosmology, and next-generation telescopes such as EUCLID and JWST are opening up the path to the first precision constraints on reionisation derived from the Lyman-alpha damping wing signature imprinted by the foreground neutral intergalactic medium (IGM) on the spectra of high-redshift quasars.

We developed a new simulation-based inference framework – coded fully differentiably in the machine learning framework JAX – to disentangle the IGM damping wing from a quasar's unknown intrinsic spectrum and infer its lifetime as well as two physical measures of the local ionisation topology in front of the quasar: the HI column density and its distance to the first neutral patch. Our pipeline accounts for all relevant modelling uncertainties, caused by IGM transmission fluctuations, quasar continuum reconstruction, and spectral noise. Enabled by a normalising flow model as neural likelihood estimator, our framework is the first that harnesses the full-resolution spectral information, including the highly non-Gaussian pixels blueward of the Lyman-alpha line. Utilising the fully generative nature of normalising flows and analysing higher-order statistics of synthetic flow-generated spectra, we demonstrate that our model has truly learned non-Gaussian information, significantly tightening the resulting parameter constraints.

Based on realistic mock spectra resembling the distribution of our ongoing 94-hour Cycle 4 JWST program and upcoming quasars found by Euclid, we show that we will soon be able to robustly constrain the evolution of the IGM neutral fraction at the <5% level between 6 ≲ z ≲ 10. We present the first such constraints for 41 ground- and/or JWST-based quasar spectra at 5.75 < z < 7.6, constraining both global timing and the local ionisation topology near these objects, and simultaneously conducting an unprecedented census of the lifetimes of these quasars, holding crucial information about supermassive black hole growth.

Detection of auroral radio emission from exoplanets presents a unique opportunity to directly probe their magnetic fields. By studying the magnetic characteristics of exoplanets, we can better-understand their atmospheric retention, long-term evolution, and ultimately their habitability. However, an unambiguous detection remains elusive, largely due to limited sensitivity at low radio frequencies. Ultracool dwarfs (UCDs), with masses between those of low-mass stars and giant planets, provide an important bridge between stellar and planetary magnetism. As fully convective, rapidly rotating objects, they sustain strong, large-scale magnetic fields that power auroral radio emission. Such emission has been detected from UCDs for over two decades, establishing them as key analogues of Jupiter-like planets and offering a valuable comparison to exoplanets, where detections have yet to be confirmed.
To date, auroral radio emission from UCDs has been observed at both high and low radio frequencies, corresponding to strong and weak magnetic field strengths, respectively. However, UCD aurorae have yet to be detected in the 400-800 MHz range, leaving open the question of whether objects at the star–planet boundary possess intermediate-strength magnetic fields. In this talk, I will present the first survey of 115 UCDs in this frequency range using the CHIME radio telescope. I will demonstrate how monitoring the rotational variability of auroral emission from each of our targets will enable us to characterise their magnetic fields. Finally, I will show how this developed framework will facilitate long term monitoring of magnetic activity of objects at the star-planet boundary, providing new constraints on how magnetism manifests from stars to planets.