[Astro] [CAPT] CAPT Weekly Bulletin (w/c 11-05-26) UPDATED (again!)

Mon May 11 08:36:11 BST 2026

Monday 11th May at 3pm, A113 CAPT – Theoretical Physics Student Seminar

Thomas Martin

Brownian Motion and Critical Dynamics

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Tuesdays at 11am, CAPT Foyer – Astro Coffee

Tuesdays at 10am, A113 CAPT – Astronomy Journal Club

Tuesday 12th May at 1pm, C12 Physics – Particle Cosmology and Gravity Seminar

Katy Clough (Queen Mary, London)

Probing beyond GR and the Standard Model using gravitational waves
I will discuss recent numerical simulations that model deviations from the vacuum BH + GR paradigm in the strong field regime of comparable mass black hole mergers. I will review recent advances, and highlight the challenges ahead to properly model these effects and test them in real data.

Link to join: https://teams.microsoft.com/l/meetup-join/19%3ameeting_OGM3OTk5NzQtZWEwZS00ZmUyLTk3MGUtZjFhY2M5OTU2MjI1%40thread.v2/0?context=%7b%22Tid%22%3a%2267bda7ee-fd80-41ef-ac91-358418290a1e%22%2c%22Oid%22%3a%22f3250584-4b5f-48fa-a897-08e77f2246b7%22%7d
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Wednesday 13th May at 2pm, A113 Physics – Particle Cosmology and Gravity Seminar

Maria Mylova (IPMU, Japan)

Gauge fixing in open quantum systems
Understanding how to gauge-fix open quantum field theories is essential for building consistent open frameworks for cosmology and gravity, where gauge symmetry must coexist with dissipation and noise and decoherence. I will present our recent work developing explicit top-down constructions of open effective field theories (EFTs) for gauge degrees of freedom, with particular emphasis on the role of gauge fixing. We implement BRST quantisation on the Schwinger-Keldysh contour and show that the in-in boundary conditions reduce the doubled global BRST symmetry to a single diagonal copy. This diagonal BRST symmetry is nevertheless sufficient to guarantee that the influence functional remains gauge invariant under two independent gauge transformations, retarded and advanced, independently of the choice of initial state, the presence of symmetry-breaking phases, and whether the gauge theory is Abelian or non-Abelian. I will also remark that once a consistent quantisation scheme is chosen, the Schwinger-Keldysh path integral is uniquely determined, and with it the rules that constrain the construction of open EFTs.  I will conclude by outlining bottom-up implications, and how these principles provide a systematic route to causal, gauge-invariant open EFTs suitable for cosmological and gravitational applications.

Based on:
Gauging Open EFTs from the top down https://arxiv.org/abs/2512.17089
Schwinger-Keldysh path integral for gauge theories https://arxiv.org/abs/2604.26941

Link to join: https://teams.microsoft.com/l/meetup-join/19%3ameeting_OGM3OTk5NzQtZWEwZS00ZmUyLTk3MGUtZjFhY2M5OTU2MjI1%40thread.v2/0?context=%7b%22Tid%22%3a%2267bda7ee-fd80-41ef-ac91-358418290a1e%22%2c%22Oid%22%3a%22f3250584-4b5f-48fa-a897-08e77f2246b7%22%7d

Wednesday 13th May at 3.45pm, C4 Physics – Astronomy Weekly Seminar

Dr Giulia Lusetti (Open University)

From diffuse cluster emission to compact jets: a LOFAR perspective on the life cycle of radio plasma

Relativistic particles and magnetic fields trace some of the most energetic processes in the Universe. In galaxy clusters—the largest gravitationally bound systems in the universe—these components are revealed through diffuse radio emission associated with mergers and shocks, as well as through radio galaxies powered by active galactic nuclei (AGN). Traditionally, these phenomena have been studied separately; however, growing observational evidence suggests that they are physically connected through the life cycle of relativistic plasma.

In this seminar, I will present results on diffuse radio emission and radio galaxies in cluster environment and discuss how AGN activity may provide a seed population of relativistic electrons that is later re-accelerated by cluster-scale processes. All of this is viewed through the unique lens of LOFAR, whose combination of very low-frequency coverage and high sensitivity is revealing previously “hidden” radio sky phenomena. Being a European-based array, LOFAR has recently demonstrated its strength not only in probing faint, diffuse emission, but also in reaching sub-arcsecond resolution through very long baseline interferometry (VLBI). In the second part of the talk, I will showcase how these capabilities can be used to study galaxy-scale jet sources out to redshift 3 and beyond. Thanks to VLBI, it is now possible to resolve (<100 kpc) structures that were previously unresolved in standard LOFAR observations, enabling detailed studies of their interplay with their host galaxies.

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Thursday 14th May at 1pm, A113 CAPT – Astronomy Lunch Talks

Mathias Urbano
An overview of the Low Surface Brightness Science with the Euclid Space Telescope

During this talk, I will revisit the efforts carried out during my PhD to conduct some of the first studies with Euclid in the Low Surface Brightness (LSB) Universe regime. This will be illustrated through the study of structures spanning three different angular scales: mock dwarf galaxies that I used to assess Euclid’s detection performance in the LSB regime for objects up to arcminute scales; tidal features investigated within the framework of Euclid’s first test observations within a single observation (0.56 square degrees); and the intracluster light of the Fornax cluster, which extends over several degrees.

Paloma Morilla

Signatures of fuzzy dark matter inside radial critical curves

We explore how fuzzy dark matter (FDM) would modify strong gravitational lensing magnification, focusing on the region near radial critical curves. Using simulated galaxy-scale lenses, we compute magnification maps for a range of halo configurations and axion masses. We find that, compared to standard cold dark matter (CDM), FDM produces a significantly higher probability of strong central magnification, an effect that is difficult to reproduce in CDM (even when subhaloes are included). The strength and characteristic scale of this enhancement are set primarily by the de Broglie wavelength, and therefore by the axion mass and halo mass. For galaxy-mass haloes, axion masses in the range $m_\phi~10^{-22}-10^{-21}$ eV lead to distinctive magnification distributions. These results suggest that observations of highly magnified, compact sources near radial arcs could provide a sensitive and complementary test of fuzzy dark matter.

Thursdays at 3pm, A113 CAPT – Particle Cosmology Journal Club

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Fridays at 4pm, CAPT Foyer – CAPT Cakes
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If you have any events/visitors you would like included in next week’s bulletin, please let me know.

Best wishes

Ella

Ella Batchelor (she/her)
Administrator

School of Physics & Astronomy

University of Nottingham
A112a Centre for Astronomy & Particle Theory
University Park
Nottingham, NG7 2RD

+44 (0) 115 74 86778 |  nottingham.ac.uk<http://nottingham.ac.uk/>

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