Next Colloquia

Precision cosmology is entering a new golden era, with current and upcoming surveys mapping the distribution of galaxies to an unprecedented level of detail. However, uncertainties in the theoretical modelling of the Universe on small, non-linear scales remain a major roadblock to interpreting these cosmological measurements. While machine learning has greatly enhanced our ability to analyse large datasets, its “black box” nature often limits physical interpretability and trust in their results. I will discuss recent advances in modelling cosmological observables in the non-linear regime using artificial intelligence (AI), and on the impact of baryonic feedback on cosmological observables. I will introduce deep learning frameworks that are explicitly designed to be interpretable and explainable in terms of the underlying physics of interest, and demonstrate their application to properties of cosmic structures. I will then present applications to the cosmic microwave background, revealing to which parameters the temperature power spectrum is sensitive in the context of early dark energy models.

• Speaker: Hamburg University
• Thursday 20 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

Precision cosmology is entering a new golden era, with current and upcoming surveys mapping the distribution of galaxies to an unprecedented level of detail. However, uncertainties in the theoretical modelling of the Universe on small, non-linear scales remain a major roadblock to interpreting these cosmological measurements. While machine learning has greatly enhanced our ability to analyse large datasets, its “black box” nature often limits physical interpretability and trust in their results. I will discuss recent advances in modelling cosmological observables in the non-linear regime using artificial intelligence (AI), and on the impact of baryonic feedback on cosmological observables. I will introduce deep learning frameworks that are explicitly designed to be interpretable and explainable in terms of the underlying physics of interest, and demonstrate their application to properties of cosmic structures. I will then present applications to the cosmic microwave background, revealing to which parameters the temperature power spectrum is sensitive in the context of early dark energy models.

• Speaker: Hamburg University
• Thursday 20 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

Precision cosmology is entering a new golden era, with current and upcoming surveys mapping the distribution of galaxies to an unprecedented level of detail. However, uncertainties in the theoretical modelling of the Universe on small, non-linear scales remain a major roadblock to interpreting these cosmological measurements. While machine learning has greatly enhanced our ability to analyse large datasets, its “black box” nature often limits physical interpretability and trust in their results. I will discuss recent advances in modelling cosmological observables in the non-linear regime using artificial intelligence (AI), and on the impact of baryonic feedback on cosmological observables. I will introduce deep learning frameworks that are explicitly designed to be interpretable and explainable in terms of the underlying physics of interest, and demonstrate their application to properties of cosmic structures. I will then present applications to the cosmic microwave background, revealing to which parameters the temperature power spectrum is sensitive in the context of early dark energy models.

• Speaker: Hamburg University
• Monday 17 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

As we move towards an epoch of rocky exoplanet discovery, I will discuss how observations of planetary material in the atmospheres of white dwarfs can inform us about planetary composition and geology. Planetary material in the atmospheres of white dwarfs informs our understanding of the link between host star and planet compositions, as well as the journey of volatiles, crucial for habitability, from planet forming discs into rocky planets.

• Speaker: Amy Bonsor (University of Cambridge)
• Thursday 27 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

The first deep images with the James Webb Space Telescope (JWST) have transformed our view of the Universe. From day one, JWST produced one surprise after another: from unexpectedly luminous candidate galaxies at z>10, to an abundant, new class of obscured black holes, to massive quiescent galaxies when the Universe was only 1-2 Gyr old. With its unparalleled imaging and spectroscopic capabilities, JWST immediately extended our cosmic horizon into uncharted territory, with galaxies spectroscopically confirmed to z14 and candidates identified out to z16-25, only 200 Myr after the Big Bang. We are thus at the brink of finding the first galaxies that ended the cosmic Dark Ages and started the reionization of the Universe. Furthermore, a surprising number of galaxies show broad-line emission in the early Universe indicating a very rapid build-up of early black holes. This includes an enigmatic new population known as ‘Little Red Dots’, characterized by their compact morphology and extremely red rest-frame optical colors. In this talk, I will review how far we have come in understanding early galaxy and black hole build-up thanks to the revolutionary new data with JWST over the past 3 years and discuss the implications for models of cosmic dawn.

• Speaker: Pascal Oesch
• Thursday 04 December 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

Over the last two decades, high-cadence rolling surveys (e.g., PS1 , ZTF, ATLAS ) have given us large statistical samples of supernovae (SNe) and other transients in the low-z range up to redshifts of 1. With JWST , going deeper and redder, we can now expand transient astronomy into the early, high-z universe. Such unique observation on high-z transients offers us a direct approach for probing the IMF at high-z, the epoch of reionization, as well as exploring the cosmological expansion history. Those sample can also provide insights into the rare types of transients (e.g., Pair-Instability SNe and Superluminous SNe) and could deepen our understanding in high energy physics and explosion mechanisms underneath. I will discuss our recent discovery of more than 100 SNe up to z~5 with the JADES and COSMOS project, their spectroscopic follow-up, and what we can expect in the future with both JWST and Roman.

• Speaker: Armin Rest
• Thursday 13 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

Understanding how galaxies form and evolve requires connecting two traditionally separate frontiers of astrophysics: the physics of baryons that shape stars, gas, and black holes, and the cosmological framework that governs dark matter and dark energy. Over the past decade, a new generation of observations: spanning imaging and spectroscopic surveys, cosmic microwave background maps, and X-ray data, has begun to reveal how these components fit together into a single, coherent picture of structure formation. In this talk, I will discuss recent progress toward building an integrated view of baryons across cosmic time: how the gas that fuels galaxies and black holes traces, cools, and feeds back into the cosmic web. I will show how combining cosmological and astrophysical probes, from large-scale galaxy redshift surveys like DESI and photometric experiments like Rubin Observatory, to CMB secondary anisotropies (the thermal and kinematic Sunyaev–Zel’dovich effects), allows us to directly map where the Universe’s ordinary matter resides and how energetic processes such as supermassive black hole feedback redistribute it. These advances not only illuminate key aspects of galaxy formation and evolution but also have profound implications for cosmology. The influence of baryons on the distribution of matter represents one of the dominant sources of uncertainty in weak lensing and clustering measurements, and hence in our efforts to pin down the nature of dark matter and dark energy. By linking multi-wavelength observations with next-generation simulations, we can now begin to bridge this gap, connecting the smallest scales of galaxy formation with the largest scales of the cosmic web, and turning the messy physics of baryons into a new window on fundamental physics.

• Speaker: Boryana Hadzhiyska
• Thursday 30 October 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

As the poster child of directly-imaged exoplanets, the HR 8799 system consists of four young gas giant planets that are likely to be in mean motion resonance. Their formation origin and evolutionary history remain uncertain but can be constrained by a rich set of archival and newly-obtained proprietary data. I will present the detection of key molecular species such as H2O and CO in the planetary atmosphere using the combination of high-contrast imaging and high-resolution spectroscopy. Despite solid detections, interpreting the data through spectral retrieval analysis has been controversial, largely due to systematics introduced by inhomogeneous data sets and differing underlying model assumptions. I will present a calibration procedure using benchmark brown dwarfs to understand the systematic errors. This leads to an accurate constraint of atmospheric composition, which in turn allows us to robustly trace the formation history. Moreover, using a sample of directly-imaged exoplanets including the HR 8799 planets, we convert their atmospheric metallicities to the accreted mass of solid during formation through a Bayesian framework that marginalizes the probabilities of disk conditions, formation locations, planetary interior structures, and accretion physics. We show that more than 50 M⊕ solid mass has been accreted, pointing to an extremely early formation time scale (

• Speaker: Ji Wang
• Thursday 06 November 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

One of the major surprises provided by the first three years of early Universe observations by JWST has been the detection of a stunning overabundance of luminous, and likely massive, galaxies at redshift z10. As the first spectroscopic confirmations are accumulating, it is crucial and timely to investigate these important and yet unknown aspects of early galaxy formation and evolution. At a time at which ALMA has laid the foundations of our understanding, Webb seems to hint at a possibly conflicting scenario. These (apparent?) contradictions need to be solved in the framework of studies that combine theory, cosmological simulations and the most advanced IR/sub-mm observations. I will analyze possible new scenarios and propose preliminary answers to the above questions.

• Speaker: Andrea Ferrara
• Thursday 23 October 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

One of the major surprises provided by the first three years of early Universe observations by JWST has been the detection of a stunning overabundance of luminous, and likely massive, galaxies at redshift z10. As the first spectroscopic confirmations are accumulating, it is crucial and timely to investigate these important and yet unknown aspects of early galaxy formation and evolution. At a time at which ALMA has laid the foundations of our understanding, Webb seems to hint at a possibly conflicting scenario. These (apparent?) contradictions need to be solved in the framework of studies that combine theory, cosmological simulations and the most advanced IR/sub-mm observations. I will analyze possible new scenarios and propose preliminary answers to the above questions.

• Speaker: Andrea Ferrara
• Thursday 23 October 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

In this talk I would like to present the LEWIS project. Looking into the faintEst WIth MUSE (LEWIS) is an ESO large program, granted with 133.5hrs with MUSE @ESO-VLT., is the first homogeneous integral-field spectroscopic survey of 30 extremely low-surface-brightness (LSB) galaxies in the Hydra I cluster of galaxies, where the majority of LSB galaxies in the sample (22 in total) are ultra-diffuse galaxies (UDGs). Because of their LSB nature, getting spectroscopic data for UDGs is a challenging task. To date, as opposed to the availability of deep images, we still lack a statistically significant sample of UDGs with spectroscopy, which strongly limits our constraints and conclusions on their stellar populations and DM content. Doubling the number of spectroscopically studied UDGs, with the LEWIS project we will make a decisive impact in this field. With LEWIS we will map, for the first time, i) the 2D stellar kinematics, ii) the stellar population and iii) established the GC population and their specific frequency of a complete sample of UDGs in a galaxy cluster with IF spectroscopic data. The structural properties together with the baryonic versus DM fraction are used in comparison with hydrodynamical models of UDGs to establish their formation channels as a function of their location in the cluster. With LEWIS we are probing the MUSE capabilities to map the galaxy structure down to the faintest surface brightness levels.

• Speaker: Enrica Iodice
• Thursday 09 October 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

How did galaxies start forming stars? What are the conditions in typical low-mass, star-forming galaxies at z8 and above? Recent observations with JWST indicate several critical puzzles in studies that address these questions. Chief among these, galaxies started forming stars early and possibly at an extraordinary rate and in more compact clumps than previously thought. I will present the latest results from the JWST Bullet Cluster observations, which we will use to measure the properties of dark matter. I will also show the discovery of a highly magnified z=11 lensed arc. The intrinsic luminosity of the galaxy is 0.05L*, making it the lowest luminosity spectroscopically confirmed galaxy at z>10 discovered to date. The galaxy contains three star-forming components with sizes of 10 remarkably compact globular-cluster-like clumps and spectroscopically confirmed Little Red Dots with strong AGN signatures. All these results allow the detailed studies of star formation at sub-10pc scales at the epoch of reionisation.

• Speaker: Prof. Maruša Bradač
• Thursday 16 October 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

The wide-field spectroscopic telescope (WST) will be an innovative 12-m class telescope with simultaneous operation of a large field-of-view (3 sq. degree) and high multiplex (30,000) multi-object spectrograph facility with both medium and high resolution modes (MOS), and a giant panoramic (3×3 sq. arcmin) integral field spectrograph (IFS). WST will achieve transformative results in most areas of astrophysics: e.g. the nature and expansion of the dark Universe, the formation of first stars and galaxies and their role in the cosmic reionisation, the study of the dark and baryonic material in the cosmic web, the baryon cycle in galaxies, the formation history of the Milky Way and dwarf galaxies in the Local Group, characterization of exoplanet hosts, and the characterization of transient phenomena, including electromagnetic counterparts of gravitational wave events.

This presentation will discuss current science, status and plans.

• Speaker: Prof Roland Bacon (CRAL, Lyon, FR and WST Collaboration Coordinator)
• Tuesday 01 July 2025, 11:30-12:30
• Venue: Martin Ryle Seminar Room, Kavli Building.
• Series: Institute of Astronomy Colloquia; organiser: eb694.

Add to your calendar or Include in your list

Neutron stars are the largest and the strongest magnets in the Universe. Their typical radius is around 10 km and their magnetic fields could reach values of 1e15 G. Structurally, the outer 1 km shell of a neutron star is its solid crust, while the inner part is its core. Magnetic fields shape observational properties of isolated and accreting neutron stars. Strong magnetic fields play the crucial role in explaining transient and persistent X-ray emission from Anomalous X-ray Pulsars and Soft Gamma Repeaters jointly known as magnetars. Magnetic fields are not constant and expected to evolve over time. In the last years, a significant progress was made in modelling magneto-thermal evolution of neutron star crust. Ohmic decay and Hall evolution explains multiple magnetar properties.  In this colloquium, I summarise the main observational constrains currently available on magnetic fields of neutron stars and confront them with state-of-art numerical simulations. I will explain how current and future observations help us to learn more about magnetic field evolution and its structure. I also explain how the neutron star core can be modelled and show preliminary results for field evolution in the core.

• Speaker: Andrei Igoshev, Newcastle University
• Thursday 12 June 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Mor Rozner.

Add to your calendar or Include in your list

Gravitational-wave (GW) multi-messenger astronomy holds immense promise for our understanding of the Universe, impacting studies of cosmology, the production of elements, and the final fates of stars. To date, however, only a single credible source, GW170817 , caused by the merger of two neutron stars, has been detected both in GWs and electromagnetically. I will discuss the scientific potential and challenges of observing more multi-messenger events, as motivation for the GOTO project: a UK-led transient sky survey composed of a fleet of rapidly-responding telescope arrays. The primary science driver of GOTO is scanning the sky in response to GW alerts, to search for their electromagnetic counterparts. Alongside overviewing GOTO ’s capabilities and recent multi-messenger efforts, I will present highlights from various ancillary science enabled by the array. This includes rapid localisation and characterisation of gamma-ray bursts, and discoveries of infant and extreme supernovae beyond the traditional core-collapse and thermonuclear regimes. I will also present our efforts to automate and expedite the characterisation of transients via algorithmically scheduled follow-up and citizen scientists.

• Speaker: Joseph Lyman, University of Warwick
• Thursday 12 June 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

Cosmological hydrodynamical simulations are becoming increasingly realistic by incorporating a wider range of physical processes, higher spatial resolution, and larger statistical samples. Despite ongoing trade-offs between resolution and volume, recent advances now allow for simulations that resolve the multiphase interstellar medium and capture the clumpy nature of star formation in galaxies. In this context, I will present how such simulations shed light on the coupled evolution of galaxies and their central supermassive black holes. At high redshift, galaxies tend to be gas-rich, turbulent, and star-bursting, often exhibiting irregular, compact, and disturbed morphologies. As internal turbulence subsides, many systems transition into stable, rotating disc galaxies, typically once they reach stellar masses around 1e10 Msun. Simultaneously, black hole growth is tightly linked to the dynamical state of the host galaxy. In low-mass, turbulent systems, stellar feedback can suppress nuclear gas inflows, delaying black hole growth. Only when galaxies become sufficiently massive and dynamically settled can gas efficiently reach galactic centers to fuel sustained accretion. These processes also have important implications for the spin evolution of black holes or how fast they coalesce, which can reflect the varying modes of accretion and feedback across cosmic time.

• Speaker: Yohan Dubois (Institut d’Astrophysique de Paris)
• Thursday 05 June 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Matthew Grayling.

Add to your calendar or Include in your list

I will present results on the properties of faint galaxies and AGN in the early Universe, building upon samples identified using Wide Field Slitless Spectroscopy with NIR Cam on the James Webb Space Telescope (JWST). This mode effectively turns JWST into an efficient redshift machine ideal to map out galaxy over-density. In my talk, I will focus on two topics: 1) The impact of galaxies and AGN on the reionization of the Universe, directly measured by mapping out the correlation between galaxies and ionized regions with quasar and galaxy transmission spectroscopy, and 2) The nature of broad Hα line-selected AGN (the so-called Little Red Dots) that JWST has uncovered in the first few Gyr, including new results based on the deep NIR Cam grism spectroscopy of their large-scale environments, deep high resolution spectroscopy unveiling the prevalence of dense absorbing gas and resolved Lyman-alpha mapping of the circumgalactic medium with VLT /MUSE. Finally, I will synthesize what these observations are learning us in the context of galaxy – SMBH co-evolution, SMBH formation and their role in cosmic reionization.

• Speaker: Dr Jorryt Matthee
• Thursday 29 May 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: Jan Scholtz.

Add to your calendar or Include in your list

Cosmological and astrophysical observations provide clear evidence for the existence of dark matter and have begun to map its distribution across vast cosmic volumes, yet key questions about its mass and interaction properties remain unanswered. Clues may lie in measurements that probe structure formation on the smallest scales—including dwarf galaxies, strong gravitational lenses, and stellar streams. These observations are already constraining aspects of the microphysical nature of dark matter, including its free-streaming behavior, decay lifetime, self-interactions, and possible interactions with the Standard Model. The upcoming generation of wide-field imaging surveys—including Euclid, the Vera C. Rubin Observatory, and the Roman Space Telescope—combined with spectroscopic surveys such as DESI and the new Via Project, will accelerate our ability to probe this physics. These efforts may detect, for the first time, dark matter halos below the threshold for star formation, directly testing a fundamental prediction of the standard cosmological model and offering the possibility of uncovering definitive astrophysical signatures of dark matter’s particle properties.

• Speaker: Risa Wechsler (Stanford/KIPAC)
• Thursday 19 June 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy (and online - details to be sent by e-mail).
• Series: The Kavli Lectures; organiser: Steven Brereton.

Add to your calendar or Include in your list

The Milky Way experienced a major satellite merger 10 Gyr ago which altered, but did not destroy, the early high-alpha disk and created both an accreted and an in situ inner halo. The low-alpha disk that formed subsequently became bar-unstable 8 Gyr ago, creating the b/p bulge that also contains the inner high-alpha disk stars. M31 experienced a similar major satellite merger 3 Gyr ago which greatly heated and mixed the pre-existing high-metallicity disk, and also caused a massive inflow of gas and the formation of a dynamically hot secondary inner disk. Such a merger is consistent with the wide-spread star formation event 2-4 Gyr ago seen in disk colour-magnitude diagrams, and with the major substructures and metal-rich stars in the inner halo of M31 , when comparing photometric and recent spectroscopic data with available models. The merged satellite must have had a broad metallicity distribution and would have been the third most massive galaxy in the Local Group before the merger.

• Speaker: Ortwin Gerhard, MPE (Garching)
• Thursday 15 May 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: .

Add to your calendar or Include in your list

Gravitational-wave observations have revealed the population of stellar remnants from a new angle. Yet their stellar progenitors remain uncertain, in particular in the case of black holes. At least a fraction of these stars is believed to form in isolated binary systems. In this talk, I will discuss how binary mass transfer affects the late evolution and final fate of massive stars. The focus will be on stars that transfer their outer layers to a companion star and become binary-stripped. Binary-stripped stars develop systematically different core structures compared to single stars. I will discuss consequences for supernovae, black hole formation, and gravitational-wave observations.

• Speaker: Eva laplace, University of Leuven, Belgium
• Thursday 22 May 2025, 16:00-17:00
• Venue: Hoyle Lecture Theatre, Institute of Astronomy.
• Series: Institute of Astronomy Colloquia; organiser: ag2017.

Add to your calendar or Include in your list