As the long term reservoir of fuel for star formation, knowledge of the neutral hydrogen (HI) properties of galaxies is essential to fully understand the build-up of the stellar mass and evolution of galaxies. With next-generation radio telescopes opening new observational frontiers in the study of HI, we can, for the first time, follow the HI emission from galaxies across cosmic time. The unprecedented quality of the SKA Observatory precursor and pathfinder telescopes provides resolved HI detections of large samples of galaxies beyond the local Universe, giving a clearer view of the cycle of gas acquisition and loss, storage and consumption. The HI scaling relations defined at z=0 are now being extended over billions of years of lookback time, yielding new inputs, as well as benchmarks to be reproduced, for the cosmological simulations of galaxy formation and evolution. As we enter the SKA era, HI observations are joining the extragalactic census in a way that has not been possible until now. This proposed IAU symposium will bring together the observational and theoretical communities to build a more complete understanding of the life cycle of galaxies, which better incorporates the information from HI observations that has often been previously missing from our multi-wavelength view of galaxy evolution.

Key Topics

  • HI in the life-cycle of galaxies
  • Connecting simulations of HI to observations
  • An unbiased and resolved view of HI in the local Universe
  • Evolution of HI galaxy scaling relations across cosmic time
  • Constraining our cosmological model with HI observations
  • Environmental processes as traced by HI
  • The smallest galaxies as revealed by their neutral gas content