Stars in some galaxies form furiously while others barely flicker, and astronomers cannot fully explain why. The WISDOM project uses the Atacama Large Millimeter/submillimeter Array (ALMA) to peer inside the cold gas clouds that birth stars, measuring whether those clouds are tightly bound and collapsing or loose and transient. By studying three types of galaxies—early-type "red and dead" galaxies, barred galaxies with star-bursting rings, and distant intermediate-redshift galaxies—the team will test how shear forces, gas inflows, and collisions control star formation. They will also weigh the supermassive black hole at each galaxy's centre using a precise method, extending these measurements to galaxies far away by exploiting gravitational lensing and machine learning. This is fundamental science. It addresses a core gap in astrophysics: why some gas turns into stars and other gas does not, and why some galaxies shine with new stars while others fade. If successful, the project will revolutionise understanding of galaxy evolution. No immediate practical application exists, but similar fundamental work on star formation and black holes has historically underpinned advances in computing, imaging, and data analysis that now quietly support satellite navigation and communications.
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Galaxies are the building blocks of our universe, but the details of how their stars form from cold gas remain unclear. In particular, given a gas reservoir, some galaxies make more stars than others. This project aims to elucidate why that is through three projects in two interrelated strands, all enabled by the revolutionary spatial resolution afforded by the Atacama Large Millimeter/sub-millimeter Array (ALMA). Building on the studies and innovative formalisms developed by the consolidated grant-supported WISDOM project, we will probe the internal structures of the stellar nurseries known as giant molecular clouds, in particular whether the clouds are bound and thus likely to form stars, or unbound and likely transient. Firstly, in so-called "read and dead" early-type galaxies, we will quantify how shear and tidal forces destruct (or not) the clouds and prevent star formation (a.k.a. morphological quenching). Secondly, in barred galaxies that often host star-bursting rings and nuclear spirals in their centres, we will explore how gas inflows and collisions lead to different internal cloud structures (a.k.a. Larson relations) and collapsing clouds. Building on the tools and extensive expertise we have developed, we will also weigh the supermassive black hole thought to lurk at the centre of every galaxy we study, thus probing black hole -- galaxy correlations with a unique, robust, and precise method across the Hubble Sequence. Most importantly, thirdly, we will extend our world-leading measurements to intermediate-redshift galaxies, thus directly (rather than indirectly via proxies) probing black hole growth. This will be achieved by exploiting strongly-lensed objects with high central magnifications and assembling purpose-built machine-learning tools. These three projects will succeed because while they aim to push existing tools and results to the next level, much can be carried out with the tools already in place. Crucially, we are not at the mercy of unpredictable time allocation committees, as enough data are already in WISDOM hands and/or the ALMA archive to carry out all three projects. The outcomes are thus all but guaranteed, and they will revolutionise our understanding of galaxy evolution by finally explaining why some gas turns into stars and other not, and why some galaxy shine brightly with new stars while others quench and fade.
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