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Most of the stars in today’s Universe were formed >8 billion years ago, but we still have a poor understanding of the sites and conditions under which they formed, as well as how their formation shaped the galaxies they reside in. Conventional wisdom – from decades of optical/NIR studies of stars and ionised gas – says that the star-forming gas in these early galaxies was more “clumpy” and turbulent than in local star-forming galaxies, supporting the most widely accepted theories of disk galaxy evolution and star-formation regulation. Yet, what leads up to star formation is the availability of its fuel, molecular gas, which has been revealed for 100s of z>1 galaxies over the last decade thanks to new sub-/mm facilities, especially the Atacama Large Millimetre/Submillimetre Array (ALMA). In this talk, I will discuss what we have learnt over the last decade by observing and modelling molecular gas at Cosmic Noon (z=1–3). I will highlight how some of these results appear to be in tension with current models of star-formation regulation and disk settling and will show how we can (literally) resolve this apparent tension with new observations and simulations of both molecular and ionised gas at Cosmic Noon. Looking to the future, I will discuss how we can better understand the processes leading up to and following star formation all the way up to Cosmic Dawn with next-generation facilities, especially the Square Kilometre Array and Extremely Large Telescope. |
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