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Sub-Neptunes are found around 50% of Sun-like stars in our galaxy. Despite their ubiquity, we lack a comprehensive understanding of their interior structure. I will present the first evolving interior structure model for sub-Neptunes that accounts for the expected miscibility between silicate magma and hydrogen. I will discuss the concept of “binodal surfaces”, which represent phase transitions within sub-Neptunes and provide a physically/chemically informed boundary between a planet’s “interior”’ and “envelope”. I will discuss the many implications of miscibility, and a potential observational route to testing its prevalence.

• Speaker: James Rogers / IoA
• Wednesday 15 October 2025, 13:15-13:40
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Xander Byrne.

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We discuss modern formulations of the strong cosmic censorship conjecture (SCCC) and possible resolutions supported by rigorous non-linear results for the spherically symmetric Einstein-Maxwell-scalar field system. We show that the presence of a positive cosmological constant suggests a violation of the SCCC at a fundamental level of regularity. Indeed, the blueshift mechanism occurring at the Cauchy horizon can be counterbalanced by the dispersive effects encoded in the exponential Price law along (cosmological) black hole event horizons. On the other hand, we show that, if non-smooth black hole solutions are allowed, then the aforementioned violations are non-generic in a positive co-dimension sense.

• Speaker: Flavio Rossetti (Gran Sasso Science Institute)
• Friday 24 October 2025, 13:00-14:00
• Venue: Potter Room / Zoom .
• Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.

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In some astrophysical flows known to be linearly stable, finite-amplitude perturbations with favourable spatial structure can nonlinearly trigger a transition from a non-magnetic, non-turbulent state to self-sustained dynamo action and turbulence. Such transitions are suspected to significantly impact spin-down in radiative stellar layers or accretion rates in stellar discs. I will first present numerical examples of nonlinearly-triggered Tayler-Spruit dynamos in a spherical shell and zero-net-flux MRI dynamos in a quasi-Keplerian plane flow. I will then discuss how optimal control can identify stable, nontrivial (M)HD equilibria without requiring prior knowledge of the transition mechanisms.

• Speaker: Florence Marcotte (Université Côte d'Azur, INRIA, CNRS)
• Monday 13 October 2025, 16:00-17:00
• Venue: MR14 DAMTP and online.
• Series: DAMTP Astrophysics Seminars; organiser: Mattias Brynjell-Rahkola.

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Fixed-term: The funds for this post are available for 24 months in the first instance.

A position exists for a Research Associate in 21-cm Cosmology within the Cavendish Astrophysics Group at the Department of Physics, University of Cambridge.

The role is funded by the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH) programme, an ambitious international effort to detect the global 21-cm signal from the early Universe, a faint imprint of the first stars and galaxies. Measuring this signal requires exquisite control over instrumental effects and advanced data analysis to separate the cosmological signal from bright astrophysical foregrounds and systematic contaminants. REACH combines precision hardware design with novel calibration strategies to push the frontier of what is achievable in low-frequency radio cosmology.

The successful candidate will play a central role in both the calibration of the REACH instrument and the analysis of its data, working at the interface of hardware and analysis. They will develop, test, and implement advanced radiometer calibration techniques and apply state-of-the-art statistical methods to extract cosmological information. The role will involve close collaboration with the wider REACH consortium of engineers, observers, and theorists, ensuring that instrument characterisation and data analysis advance hand in hand.

Applicants should hold (or be close to completing) a PhD in astrophysics, radio astronomy, physics, or a related field. The ideal candidate will have: Strong expertise in:

• Data analysis, including RFI mitigation and foreground modelling;
• Radio astronomy instrumentation and radiometry;
• Calibration pipelines and instrumental systematics;
• Programming skills in Python, C/C++ or equivalent, and the ability to handle complex datasets.
  

Experience in electromagnetic simulations, radiometer design, or low-frequency calibration techniques would be advantageous. Strong communication and collaboration skills are essential.

The post holder will be based at the Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0US, UK, working under the supervision of Professor Eloy de Lera Acedo.

Salary Ranges: Research Associate: £37,694 -£46,049 (Grade 7) Research Assistant (if PhD not yet awarded): £34,610 (Grade 5)

Appointment at Research Associate level is dependent on having a PhD. Those who have submitted but not yet received their PhD will initially be appointed as a Research Assistant moving to Research Associate (Grade 7) upon confirmation of your PhD award.

Click the 'Apply' button below to register an account with our recruitment system (if you have not already) and apply online.

Please ensure that you upload your Curriculum Vitae (CV) and a covering letter, in the upload section of the online application. If you upload any additional documents which have not been requested, we will not be able to consider these as part of your application. Please submit your application by midnight on the closing date.

If you have any questions about this vacancy please contact Prof. Eloy de Lera Acedo (ed330@cam.ac.uk). If you have any questions about the application process, please contact hr@phy.cam.ac.uk.

Please quote reference KA47583 on your application and in any correspondence about this vacancy.

The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.

The University has a responsibility to ensure that all employees are eligible to live and work in the UK.

Abstract not available

• Speaker: Antony Lewis (University of Sussex)
• Monday 20 October 2025, 13:00-14:00
• Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
• Series: Cosmology Lunch; organiser: Louis Legrand.

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Venerable Exoplanetary Systems, a brief history: Revelations from 100 years ago to some new discoveries via an unusual, entirely unanticipated, observational technique. The discussion will include the first ever observational evidence for the existence of an extrasolar planetary system, the first observational evidence for the existence of a differentiated extrasolar planet (i.e., one with a crust and mantle), and the remarkable discovery of objects with 100s of times larger abundances of the light elements Be and B than previously seen in any astronomical object.

• Speaker: Prof. Ben Zuckerman
• Tuesday 14 October 2025, 13:00-14:00
• Venue: HOYLE LECTURE THEATRE + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr. Mariona Badenas Agusti.

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Venerable Exoplanetary Systems, a brief history: Revelations from 100 years ago to some new discoveries via an unusual, entirely unanticipated, observational technique. The discussion will include the first ever observational evidence for the existence of an extrasolar planetary system, the first observational evidence for the existence of a differentiated extrasolar planet (i.e., one with a crust and mantle), and the remarkable discovery of objects with 100s of times larger abundances of the light elements Be and B than previously seen in any astronomical object.

• Speaker: Prof. Ben Zuckerman
• Tuesday 14 October 2025, 13:00-14:00
• Venue: HOYLE LECTURE THEATRE + ONLINE - Details to be sent by email.
• Series: Exoplanet Seminars; organiser: Dr. Mariona Badenas Agusti.

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M-theory provides a geometric framework to describe a variety of interesting quantum field theories in which the QFT ’s arise from Einstein metrics. We motivate a precise definition of this framework which (partly) takes the form of the space of complete, asymptotically conical Ricci flat manifolds in various dimensions. We show how this provides insights into various strongly coupled systems such as non-Abelian gauge theories in four and more dimensions and leads to confining string theories in four and five dimensions. The four dimensional strings can be compared to flux tubes in Yang-Mills theories.

• Speaker: Bobby Acharya (ICTP Trieste)
• Thursday 09 October 2025, 12:00-13:00
• Venue: MR9/Zoom https://cam-ac-uk.zoom.us/j/81827907718.
• Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.

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Cosmological collapse, where gravitational pull overcomes the universe’s expansion, can create primordial black holes or other bound structures. The ultimate fate of such a collapse depends on the initial distribution of matter and its equation of state, as pressure counteracts the gravitational infall. Then, in the dust case, where there is no pressure, shouldn’t a black hole always form? In this talk, I will attempt to answer this question using numerical relativity simulations, discussing the challenges of this problem and the progress we have made so far. Additionally, as this is in full GR, it presents an opportunity to characterise the cosmological spacetime; therefore, I will also describe this using gravito-electromagnetism and Weyl invariants.

• Speaker: Robyn Munoz (Sussex University)
• Friday 17 October 2025, 13:00-14:00
• Venue: Potter Room / Zoom .
• Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.

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The Leverhulme Centre for Life in the Universe and the University of Cambridge are committed to widening participation in postgraduate students at the University of Cambridge. Research within the Centre aims to develop a deeper understanding of life, its emergence, and its distribution in the Universe by addressing four questions:

What are the chemical pathways which led to the origins of life that are compatible with benign conditions for life in different planetary environments?

How do we characterise the environments on Earth and other planets that could act as the cradle of prebiotic chemistry and life?

What observational facilities and methods will allow investigation of bodies beyond the Solar System, the remote sensing of their atmospheres and the search for signatures of geological and biological evolution?

How can philosophical and mathematical concepts refine our understanding of what we mean by life, leading to new interdisciplinary collaborations and modes of scientific enquiry?

We have a fully funded PhD studentship available for home (UK) students starting October 2026. This studentship will cover fees and stipend for home students at the UKRI + LCLU uplift of £1,000 per year for 4 years and research cost support will be provided.

Eligibility is reserved for applicants who meet at least one of the following criteria:

have been in receipt of free school meals at secondary school;

be in the first generation of your family to study at undergraduate level;

have been a young carer under the age of 18 or have/ had caring responsibilities during your undergraduate study (providing unpaid support for a family who has a physical or mental health condition, or misuses substances);

have entered university at undergraduate level from a care background or as a Foyer resident;

be estranged from your parents/guardians;

receive/ received the maximum Maintenance Loan for undergraduate study;

have refugee status.

To apply go to the University of Cambridge postgraduate admissions portal: https://www.postgraduate.study.cam.ac.uk/ and note in the applying for funding section that you are eligible for LCLU funding. The materials required for your application will depend on the department of the primary PhD supervisor, details available here: https://www.postgraduate.study.cam.ac.uk/applying/how-do-i-apply. The deadlines for applications vary with the department, so please check what the relevant deadline is with the relevant PhD Supervisor, since some departments have earlier deadlines, such as 2nd December 2025. All applications will have to be in by 11:59 pm GMT 7th January 2026.

The list of research proposals 2025 can be seen here: https://www.lclu.cam.ac.uk/research-proposals-2025 The list of projects is not exhaustive, and applicants are encouraged to approach any of our supervisors with their own project ideas. If you would like to propose your own research topic, you can also browse through the list of supervisors with research interests to find those that particularly interest you. (https://www.lclu.cam.ac.uk/supervisors). You should contact prospective supervisors before applying, to further explore your mutual interests, and to get additional advice and information.

Participating Departments at the University of Cambridge are: Cavendish Laboratory, Institute of Astronomy, Department of Applied Mathematics and Theoretical Physics, Yusuf Hamied Department of Chemistry, Department of Biochemistry, Department of Earth Sciences, Department of Zoology, Department of History and Philosophy of Science, Faculty of Divinity, and the MRC Laboratory of Molecular Biology.

Fixed-term: The funds for this post are available for 4 years in the first instance.

For further details please visit: https://www.lclu.cam.ac.uk/studentship-opportunities/lclu-phd-studentships

For any enquiries, please contact: admin@lclu.cam.ac.uk

Please quote reference KA47577 on your application and in any correspondence about this vacancy.

The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.

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.

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Abstract not available

• Speaker: Houda Haidar (Newcastle)
• Friday 23 January 2026, 11:30-12:30
• Venue: Ryle Seminar Room, KICC + online.
• Series: Galaxies Discussion Group; organiser: Sandro Tacchella.

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Many presentations of quantum mechanics include a postulate that the state of a system undergoes an instantaneous change following a measurement. This is clearly incompatible with special and general relativity and raises questions concerning the description of measurement in quantum field theory (QFT).

Attempts to extend measurement postulates to QFT by hand have produced pathologies, such as the “impossible measurements” described long ago by Sorkin.

I will present a recent operational approach to these questions, which models measurement of one quantum field (the system) by coupling it to another (the probe). This is all accomplished in a model-independent way within algebraic quantum field theory (AQFT). The resulting framework provides a description of measurement in QFT that is causal, covariant and consistent, and includes state update rules that are derived from the formalism, and works equally well in flat or curved spacetimes. As well as covering the basics of the formalism and how it resolves Sorkin’s impossible measurement problem, I will touch on some more recent developments, including links to quantum reference frames.

I will not assume any prior knowledge of AQFT .

The talk is mostly based on joint work with Rainer Verch (Comm. Math. Phys. 378 (2020) 851-889 arXiv:1810.06512) and further work with Henning Bostelmann, Maximilian Ruep and Ian Jubb (see https://arxiv.org/abs/2304.13356 for a survey). I will also mention recent joint work with Daan Janssen, Leon Loveridge, Kasia Rejzner, James Waldron (Comm. Math. Phys. 406:19 (2025) https://arxiv.org/abs/2403.11973)

• Speaker: Professor Chris Fewster - York
• Wednesday 22 October 2025, 16:00-17:00
• Venue: MR3.
• Series: Theoretical Physics Colloquium; organiser: Amanda Stagg.

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Scalar fields are ubiquitous in string theory compactifications, arising both from geometric moduli and as descendants of higher-dimensional p-forms. In cosmology, they provide natural candidates to drive accelerated expansion, both during early (inflationary) and late (dark energy) time evolution of the Universe. In single-field models, scalar potentials are typically too steep to sustain slow-roll evolution. However, in multifield scenarios, accelerated expansion can occur even for steep potentials, when the scalar fields move along strongly non-geodesic trajectories in field space. Such dynamics not only enable inflation or dark energy but can also evade recent quantum gravity swampland constraints. In this talk, I will show how to extend the dynamical systems (DS) toolkit to include both kinetic and potential couplings between fields – features that naturally arise in string-theoretic constructions. Within this framework, I will present a compact and general expression for the non-geodesicity parameter, which offers a simple and transparent diagnostic of truly multifield evolution. I will also discuss connections with previous work on inflationary dynamics, where related mechanisms play a central role.

• Speaker: Ivonne Zavala (Swansea U.)
• Monday 13 October 2025, 13:00-14:00
• Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
• Series: Cosmology Lunch; organiser: Gonzalo Villa.

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Planet formation unfolds in environments where stars are rarely alone: the majority of stellar systems are binaries, triples, or higher-order multiples. Hence, stellar multiplicity profoundly shapes the structure, evolution, and dynamics of protoplanetary discs. In this talk, we will explore how discs evolve under the gravitational influence of multiple stars and how this impacts planet formation. I will first summarise recent theoretical and numerical studies on disc dynamics in binary and triple systems, complemented by illustrative examples from observations (e.g. ALMA and VLT ) of young multiple stellar systems with discs and planets. Next, I will discuss our modelling efforts within the Stellar-MADE ERC project to investigate accretion, disc morphology, and orbital architecture in these complex systems. Finally, we will highlight the implications for dust evolution, planet formation, and long-term planetary stability.

• Speaker: Nicolás Cuello (IPAG Grenoble)
• Monday 27 October 2025, 16:00-17:00
• Venue: MR14 DAMTP and online.
• Series: DAMTP Astrophysics Seminars; organiser: Thomas Jannaud.

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Dust grains are key players of the evolution of the dense interstellar medium. The grain size distribution varies locally, modifying the thermodynamics and the chemistry of molecular clouds, the opacity of collapsing protostellar cores and the coupling between the gas and the magnetic field, and the solid content to form planetesimals in protoplanetary disks. Magnetohydrodynamical models are commonly used to study the formation of stars and disks, but they generally do not capture the complexity of the interactions with the dusty component.

This complexity requires analytical and numerical methods that offer complementary levels of detail. In the first part of the talk, I present a multifluid approach that models the dynamics of a dust size distribution in interaction with the gas and the magnetic field. We explore its fundamental physics in the linear regime. We discuss the consequences of the coupling of the dust with the magnetic field on dust enrichment within the protostellar envelope and on magnetic braking (Verrier et al, in prep). In a second part of the talk, I present our new multifluid numerical method that allows us to simulate 3D dusty protostellar collapses (Verrier et al, 2025). This method is designed to capture all the coupling regimes between the gas and the neutral dust grains, including the terminal velocity regime (Lebreuilly et al, 2019). We find that millimeter dust grains enrich the first hydrostatic core and some locations of the envelope, promoted by the initial turbulence of the dense core, setting favourable conditions to early planet formation scenarios. Finally, we present perspectives that connect dust dynamics in turbulence and dust growth.

• Speaker: Gabriel Verrier (CEA Saclay, France)
• Wednesday 15 October 2025, 14:00-15:00
• Venue: MR14 DAMTP and online.
• Series: DAMTP Astrophysics Seminars; organiser: Thomas Jannaud.

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Understanding the generation of large-scale magnetic fields and flows in MHD turbulence remains one of the most challenging problems in astrophysical fluid dynamics. The well-studied kinematic theory ignores the possibility of small-scale dynamo action, which is prevalent at high magnetic Reynolds number. Here, we thus examine the possibility of large-scale field (and flow) arising from a fully MHD basic state — as may arise from the saturation of a small-scale dynamo. Under this new theory, four mean field tensors now come into play. In certain cases, such as “short-sudden” turbulence, these tensors may be calculated explicitly. More generally, the (nonlinear) mean field theory works well for mildly turbulent flows, but can fail in strongly disordered systems. This leads us to address the more general dynamical systems question of whether a linear response can be detected following a  small (linear) perturbation to a chaotic system.

• Speaker: David Hughes (Leeds)
• Monday 17 November 2025, 16:00-17:00
• Venue: MR14 DAMTP and online.
• Series: DAMTP Astrophysics Seminars; organiser: Loren E. Held.

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Our recent work (2509.13307) demonstrated the performance of GPU -accelerated nested sampling for efficient high-dimensional Bayesian inference in cosmology. Using JAX -based emulators and likelihoods we can leverage the parallel computing of GPUs to achieve orders of magnitude speed-ups against CPU -based analyses, and bring robust evidence calculations up to GPU -speed. This puts nested sampling back on equal footing with Markov Chain Monte Carlo (MCMC) methods, which use auto-diff gradients to achieve their speed-ups. In particular a Euclid-like mock Cosmic Shear likelihood has been considered, an analysis which previously took 8 months on a CPU instance, and we bring the time to constrain both ΛCDM and w0wa down to only 2 days on a single GPU . This talk explores a few options for pushing our methodology even further, in preparation for joint analyses of next generation of cosmlogical surveys.

• Speaker: Toby Lovick / IoA
• Wednesday 08 October 2025, 13:15-13:40
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Xander Byrne.

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I will introduce a Python package called ECHO21 for modelling the global 21-cm signal from the dark ages through cosmic dawn to the end of reionization. Leveraging its analytical framework, ECHO21 generates a single model in O(1) s, allowing a large number of signals to be generated efficiently by distributing models across multiple cores. Thus, it is ideal for performing astrophysical or cosmological inference from a given 21-cm dataset. We offer six astrophysical parameters that control the Lyman-α emissivity, X-ray emissivity, emissivity of ionizing photons, and star formation rate. Beyond its efficiency, some of the attractive and novel features in ECHO21 relative to previously published codes are the inclusion of Lyα heating, the ability to vary the standard cosmological parameters as easily as the astrophysical parameters, different models of star formation rate density (physically-motivated, a semi-empirical, and an empirically-motivated), and modelling the global signal for a Coulomb-like interacting DM (IDM) framework. This IDM model incorporates cooling of baryons as well as a delay in star formation. With several 21-cm experiments soon to provide cosmic dawn 21-cm data, ECHO21 is a flexible and extensible new open-source package for making quick and sufficiently realistic astrophysical inferences.

• Speaker: Shikhar Mittal / Battcock Centre
• Wednesday 08 October 2025, 13:40-14:05
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Xander Byrne.

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Abstract not available

• Speaker: Toby Lovick / IoA
• Wednesday 08 October 2025, 13:15-13:40
• Venue: Hoyle Lecture theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: Xander Byrne.

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