[Astro] Lunch Talk

[Michael Anderson Jennings]

Hi Everyone,

This week's lunch talk will be given by Zoe Le Conte, an external speaker coming from Durham. The talk is on Thursday at 1pm in A113. Title and abstract are below:

A JWST investigation into the bar fraction at high redshifts 𝑧 > 1

The presence of a stellar bar in a disc galaxy indicates that the galaxy hosts, in its main part, a dynamically settled disc and that bar-driven processes are taking place in shaping its evolution. Studying the cosmic evolution of the bar fraction in disc galaxies is therefore essential to understand galaxy evolution in general. Using the Hubble Space Telescope (HST), previous studies have found that the bar fraction significantly declines from the local Universe to redshifts near one. Using the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey (CEERS) and the initial public observations for the Public Release Imaging for Extragalactic Research (PRIMER), we extend the studies of the bar fraction in disc galaxies to redshifts 1 ≤ 𝑧 ≤ 3, i.e., for the first time beyond redshift two. Our sample is present in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) on the Extended Groth Strip (EGS) and Ultra Deep Survey (UDS) HST observations. The sample was visually classified to find the fraction of bars in disc galaxies in two redshift bins, and our results showed the JWST bar fraction to be twice the bar fraction found using bluer HST filters. Specifically, we find that the bar fraction is about 18% at redshifts between one and two, and about 14% at redshifts between two and three. In an upcoming study, we are doubling the sample and extending it to redshift four. We will also evaluate the evolution of the bar length to understand if bars grow with cosmic time. Our results already show that bar-driven evolution commences at early cosmic times and that dynamically settled discs are already present at a lookback time of ∼ 11 Gyrs.


Thanks,
Mikey

Mikey Anderson Jennings
Astronomy PhD Student
University of Nottingham
Centre for Astronomy and Particle Theory

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