[Astro] [CAPT] CAPT Weekly Bulletin (w/c 01-12-25)

[Ella Batchelor (staff)]

Monday 1st December at 3pm, A113 CAPT – Theoretical Physics Student Seminar

Benjamin Muntz

Dimensional analysis is a gauge theory

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Tuesdays at 11am, CAPT Foyer – Astro Coffee



Tuesday 2nd December at 1pm, A113 CAPT – Particle Cosmology and Gravity Seminar

Violetta Sagun (Southampton)

How smooth is the radio sky?
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Wednesday 3rd December at 11am, A113 CAPT – CAPT Coding Club



Wednesday 3rd December at 3.45pm, C4 Physics – Astronomy Weekly Seminar

Yuchen Ding (LJMU)

Probing the Assembly of Low Star-formation Galaxies via Population-Orbit Superposition Method



Understanding the formation of low star-formation galaxies is key to unraveling the processes that drive galaxy evolution. My talk will mainly contain three parts:

In the context of the Fornax3D project, we analyzed 21 galaxies in the Fornax cluster observed with MUSE/VLT by applying a novel population-orbit superposition method. By fitting the luminosity distribution, stellar kinematics, age and metallicity maps simultaneously, we obtained the internal stellar orbit distribution and stellar population distributions.

Based on the model, we decompose the dynamically cold disk (orbital circularity λz > 0.8) for each galaxy, and obtain its luminosity fraction, age and metallicity radial profiles.  For galaxies in the Fornax cluster, we find that the luminosity fraction of cold disk in recent infallers are consistent with field galaxies from CALIFA, while the cold disk fractions in ancient infallers with tinfall > 8 Gyr are a factor of ∼ 4 lower, with control of stellar mass. Moreover, the stellar age of cold disk is highly correlated with galaxy infall time into the cluster, and we find positive age gradients in cold disks, with stars in the inner disk being younger than those in the outer disk, contrary to the expectation of inside-out growth.



We then directly compare our results with galaxies in Fornax-like clusters in TNG50 simulations, and find that they agree with each other remarkably well on cold disk fractions, stellar age, age gradients, and their dependence on galaxy’s infall time to the cluster. In the simulations, we find gas in the outer disk was partly removed and partly compacted into the inner regions when falling into the cluster, which leads to quick stop of star formation in the outer disk, but a long tail of star formation in the inner regions. The turnover of star formation radius from out to inner regions is highly correlated with the galaxy’s infall time. This process explains most of the above results. At the same time, tidal shocking partially heats the cold disk formed before infall, which further reduces the cold disk fraction in ancient infallers which bear the strongest tidal effects.



Finally, we analyzed one low star-formation S0 galaxy in the GECKOS survey - a VLT/MUSE large program targeting 36 nearby edge-on galaxies at Milky Way mass. We find an old, metal-poor nuclear stellar disk, an extended main disk in this galaxy. It shows a strong negative age gradient in unclear disk and a strong positive age gradient in main disk. The presence of an old nuclear disk suggests the existence of an ancient bar structure. Furthermore, we find that both the cold disk fraction and the age gradient align with those observed in galaxies from the Fornax cluster, implying that environment may play only a limited role in shaping the evolution of low star-formation galaxies.

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Thursday 4th December at 1pm, A113 CAPT – Astronomy Lunch Talk

Yannick Bahé



Thursday 4th December 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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