[Astro] [CAPT] CAPT Weekly Bulletin (w/c 30-09-24)

[Ella Batchelor]

Tuesdays at 11am, CAPT Foyer – Astro Coffee



Tuesday 1st October, A113 CAPT at 11am – Astronomy Journal Club



Tuesday 1st October, A113 CAPT at 1pm – Particle Cosmology Seminar
Dibya Chakraborty (Indian Institute of Technology, Madras)
Inflationary Models in String Theory

In this talk, I will discuss a phenomenon called cosmic inflation in which the Universe went through accelerated expansion to solve the horizon problem of Cosmological Microwave Background within a billionth of a trillionth of a trillionth of a second, in the very early Universe. This accelerated expansion, in its minimal form, is driven by a scalar field (inflaton) and it takes place when this scalar field slowly rolls down a potential well. However, the origin of this scalar field and the correct form of the scalar potential remains an open question in cosmology. I will present a string theory motivated model where the inflaton is connected to the geometry of the internal space -- the overall volume of it drives the inflation. In particular, I will present a construction where the overall volume modulus (scalar field) is dynamically stabilized to an exponentially large value only via perturbative corrections, also known as perturbative large volume scenario (LVS). In this framework, the robustness of the single-field inflationary model is checked against possible sub-leading corrections. In the later part of my talk, I will focus on the global embedding of the fibre inflation in perturbative LVS and show how our constructions pose less challenge in realizing a successful period of inflation.

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 2nd October, C5 Physics at 3.45pm – Astronomy Seminar
Amy Bonsor (IoA, Cambridge)
Rocky planets and the potential for life beyond the Solar System


We live in an epoch of exoplanet discovery. Within the next decade the discovery of rocky planets orbiting other stars will be commonplace. However, in order to fully understand these exoplanetary systems and their potential to host life, we have to consider the planetary system as a whole. Information from host-star compositions, system architectures and white dwarfs that have accreted planetary material add to our intuition. I will discuss how we can start to think about whether exoplanetary systems have the right material available and the right physical conditions for the origin of life. Our exploration of planetary systems beyond the Solar System goes hand in hand with the journey of discovery of how life on Earth came to be.

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Thursday 3rd October at 1pm, A113 CAPT – Astronomy Seminar
Arif Babul (Victoria)
The Formation and Evolution Massive Galaxies in the Cosmos and their Circumgalactic Environment


Contrary to many stereotypes about massive galaxies, the observed systems are  diverse in their star formation rates, kinematic properties, and morphologies.  Studying how they evolve into and express such diverse characteristics is an important piece of the galaxy formation puzzle.     Here, we focus on a subset of massive galaxies, the brightest group galaxies (BGGs).  We use a high-resolution cosmological suite of simulations based on the Romulus galaxy formation model, and compare simulated central galaxies in group-scale halos at 𝑧 = 0 to their observed counterparts.  Since most galaxy formation models are calibrated using measures that are strongly influenced by the properties and evolution of “normal”  Milky-Way like galaxies, this exercise is also an opportunity to test the limits of these models. The comparison encompasses the stellar mass-halo mass relation, various kinematic properties and scaling relations, morphologies, and the star formation rates. We find Romulus BGGs that are early-type S0 and elliptical galaxies as well as late-type disk galaxies; we find BGGs that are fast-rotators as well as slow-rotators; and we observe BGGs transforming from late-type to early-type following strong dynamical interactions with satellites.  In short, we find that Romulus reproduces the full spectrum of diversity in the properties of the BGGs very well.  Additionally, due to its superb  mass and spatial resolution, Romulus also offers a unique window onto the joint evolution of the BGGs and the surrounding intragroup medium. With respect to the latter, we are able to observe the emergence of multiphase structure - in the form of cold clouds - in the intragroup medium.  Groups also experience  repeated AGN feedback episodes that drive  large-scale collimated outflows into the IGrM.  While the present resolution does not allow direct exploration of the coupling between the clouds and the AGN jets, we argue that the clouds will cause the SMBHs (and hence, the jets) to change direction every so often.  Returning back to the BGGs, we find that early type galaxies can rejuvenate by growing disks, in agreement with recent observations.  However, we also note a tendency towards lower than the observed fraction of quenched BGGs, with increasing halo mass.  The problem appears to be due to decreasing effectiveness of AGN feedback with increasing halo mass.  Examining some of the other galaxy formation models, we find that they too run into trouble on the same scale — but in an opposite sense. I will conclude by discussing what we are to make of this and what the path forward looks like.



Thursday 3rd October, A113 CAPT at 3pm – Particle Cosmology Journal Club
Oliver Gould
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Fridays at 4pm, CAPT Foyer – CAPT Cakes
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If you have any events/visitors you would like including 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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