[Astro] [CAPT] CAPT Weekly bulletin (w/c 25-05-26)

[Ella Batchelor (staff)]

Tuesdays at 11am, CAPT Foyer – Astro Coffee

Tuesdays at 11.30am, A113 CAPT – Astronomy Journal Club



Tuesday 26th May at 1pm, C12 Physics – Particle Cosmology and Gravity Seminar

Job Feldbrugge (Edinburgh)
Real-Time Path Integrals, Caustics and Interference in Cosmology


Interference is one of the most universal phenomena in nature, as exemplified by the real-time Feynman path integral. Despite the ubiquity of interference patterns, their evaluation has often proven challenging. This is especially apparent when considering lensing in astrophysics in the wave optics regime and when studying quantum cosmology using the path integral for gravity. The oscillatory integrals involved are frequently conditionally convergent, converge slowly, and artefacts such as dependence on unphysical cut-offs can be difficult to avoid. Traditionally, these oscillatory integrals are approximated with saddle point methods. However, determining which saddle points to include can be a tricky exercise.

Using Picard-Lefschetz theory — a general, exact method for handling multidimensional oscillatory integrals — I will present an unambiguous definition of the real-time path integral and an efficient numerical method for its evaluation. I will show that we can unambiguously identify the relevant instantons using resurgence theory. By going beyond the WKB approximation, we obtain asymptotic series whose interrelations enable us to detect which instantons contribute to the path integral. The resulting propagator consists of an interference pattern governed by the caustics of the underlying classical system. These methods pave the way to the study of real-time dynamical systems in our quantum Universe.



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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Thursday 28th May at 1pm, A113 CAPT – Astronomy Lunch Talk

James Rice
The Fate of the Cold ISM in COLIBRE Cluster Satellites



The fate of hot, tenuous HI in cluster satellites is uncontroversial, being rapidly depleted by environmental effects such as ram pressure stripping. The evolution of the cold, dense phase of the ISM in which star-forming H2 is predominant is less clear, with both deficient and H2-rich satellite samples having been found in observation. We compare the cluster satellite data of the cutting-edge COLIBRE suite of simulations to a subset of recent (past decade) CO surveys up to z ~ 1.6, before delving into COLIBRE’s independent predictions for the effects of the cluster environment on satellites and nearby centrals, and how this is affected by the orbital and infall history of the galaxies in question.



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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