[Astro] [CAPT] CAPT Weekly Bulletin (w/c: 04-11-24)

[Ella Batchelor]

Monday 4th November A113 CAPT, 3pm – Theoretical Physics Student Seminar

Altay Etkin (Southampton)

Late-Time Quantum Chaos and (Non)-Orientable Jackiw-Teitelboim Gravity

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Tuesdays at 11am, CAPT Foyer – Astro Coffee



Tuesday 5th November, A113 CAPT at 11am – Astronomy Journal Club



Tuesday 5th November, A113 CAPT at 12.30pm – Particle Cosmology and Gravity Seminar

Yuyo Mo (Higgs Centre, Edinburgh)

From On-shell amplitude in AdS to Cosmological correlators



We will begin by discussing the motivation and setup of Mellin-momentum amplitudes, along with several examples, including the Feynman rules and their associated pole structures. Following this, we will present the recursive on-shell bootstrap process, which is designed to compute higher-point Mellin-momentum amplitudes for YM and GR in AdS space. Additionally, the bootstrap can be used to derive the Class I soft theorem for Mellin-momentum amplitudes in a diagrammatic fashion. If time permits, we will also introduce a recursive method for finishing the bulk scalar integrals, which connects Mellin-momentum amplitudes to boundary CFT correlators. This process leads to the wavefunction coefficients through wick rotation, thereby providing the cosmological correlators. This talk is based on the works [2305.13894], [2402.09111], [2407.16052], and [2410.04875].


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 7th November at 1pm, A113 CAPT – Astronomy Lunch Talk

Hua Gao

IllustrisTNG in the HSC-SSP: No Shortage of Thin Disk Galaxies in TNG50



We perform a thorough analysis of the projected shapes of nearby galaxies in both observations and cosmological simulations. We implement a forward-modeling approach to overcome the limitations in previous studies, which hinder accurate comparisons between observations and simulations. We measure axis ratios of z = 0 (snapshot 99) TNG50 galaxies from their synthetic Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) images and compare them with those obtained from real HSC-SSP images of a matched galaxy sample. Remarkably, the comparison shows excellent agreement between the observations and the TNG50 simulation, challenging previous claims that ΛCDM models underproduced the abundance of thin galaxies. Specifically, for galaxies with stellar masses 10⩽log(M⋆/M⊙)⩽11.5, we find ≲0.1σ tensions between the observations and the simulation, a stark contrast to the previously reported ≳10σ tensions. We reveal that low-mass galaxies (M⋆≲10^9.5M⊙) in TNG50 are thicker than their observed counterparts in HSC-SSP and attribute this to the spurious dynamical heating effects that artificially puff up galaxies. We also find that, despite the overall broad agreement, TNG50 galaxies are more concentrated than the HSC-SSP ones at the low- and high-mass end of the stellar mass range of 9.0⩽log(M⋆/M⊙)⩽11.2 and are less concentrated at intermediate stellar masses. But we argue that the higher concentrations of the low-mass TNG50 galaxies are not likely the cause of their thicker/rounder appearances. Our study underscores the critical importance of conducting mock observations of simulations and applying consistent measurement methodologies to facilitate proper comparison with observations.



Thursday 7th November, A113 CAPT at 3pm – Particle Cosmology Journal Club
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Fridays at 2pm, A113 CAPT – CAPT Coding Club

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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