The study of high-redshift galaxy evolution is in the midst of a revolution driven by JWST. As JWST has broken the redshift frontier it has revealed populations of galaxies with excessive UV emission, peculiar chemical abundances, and extremely compact morphologies. These all hint at a common thread behind the properties of galaxies in the early Universe: their dramatic star-formation histories (SFHs). Robust observational evidence now suggests these galaxies can transform from highly star-forming to mini-quenched and back again on timescales of only tens of millions of years. Although we have observed a limited number of galaxies in lulls of star formation, the UV-faint nature of these galaxies makes them challenging to identify, raising questions about observational completeness at high redshift. We thus still lack a cohesive, statistical view of stochastic star formation in the early Universe. This represents a crucial gap in our understanding of high-redshift galaxy evolution, given that this mode of star formation may explain the excess of UV-bright galaxies, break typical assumptions in chemical evolution models, and relate directly to compact galaxy sizes.

State-of-the-art simulations indicate that these starburst and lulling phases correspond with large-scale gas inflows, local re-accretion of the interstellar medium (ISM), and stellar and black hole-driven feedback events. These different mechanisms result in a variety of physical and temporal scales that dictate the SFHs of galaxies. The large-scale environment governs significant gas accretion events from filamentary structures and mergers, funnelling gas onto the ISM. On galaxy scales, ejection of gas into the halo and re-accretion onto the ISM is believed to be crucial, while on even smaller scales, feedback events can provoke and quench star formation within individual molecular clouds.

It is therefore crucial to draw together our rapidly changing understanding of star formation on a variety of scales to provide a unified picture of star formation and the duty cycle of galaxies in the early Universe.

Programme

This EAS session is organised into three 1.5-hour blocks. The topics covered in each block are specified below.

Star formation in large-scale environments:

• The importance of gas accretion from the cosmic web in fueling star formation
• The impact of mergers in inducing early star formation
• The overall role of overdense environments on the cosmic star formation rate density

• The current understanding of the stochasticity of star formation in the early Universe and the best way of modelling it
• The variety of probes of bursty star formation histories: from emission lines, to UV luminosity and Balmer breaks
• The impact of bursty star formation on the properties of high-redshift galaxies, including their metallicities, chemical abundances, and morphology

• New insights into star formation with IFU and Grism observations, and high-resolution simulations
• The role of stellar and AGN feedback in disrupting the ISM of galaxies

Invited speakers

TBA

Scientific organisers

• Callum Witten (University of Geneva, Switzerland) - co-chair
• William McClymont (University of Cambridge, UK) - co-chair
• Pascal Oesch (University of Geneva, Switzerland)
• Laure Ciesla (LAM, France)
• Martin Rey (University of Bath, UK)
• Lola Danhaive (University of Cambridge, UK)
• Mahsa Kohandel (SNS, Italy)
• Hannah Übler (MPE, Germany)
• Maxime Trebitsch (Observatoire de Paris, France)

Contact

callum.witten @ unige.ch; wjm50 @ cam.ac.uk