Measuring the Influence of Supernovae at High Redshift

Supernovae play a large but poorly understood role in our attempts to explain the evolution of the baryonic universe. Numerous observations throughout astronomy cannot be explained if we neglect their influence, yet our quantitative understanding of the ways in which supernovae affect the universe remains remarkably poor. This is one of the most embarrassing gaps in our knowledge of the cosmos, and planned telescopes and surveys will probably not do much to fill it. The problem is that these surveys will be optimized to observe galaxies and intergalactic material independently of each other, while (in the author's view) by far the best information will come from simultaneous surveys of galaxies and the intergalactic material (IGM) in their vicinity. Only this will show directly how galaxies affect their surroundings and provide a rough energy scale for supernova-driven winds. Redshifts 1<z<3 are ideal for the joint galaxy/IGM surveys we advocate, because the comoving density of star formation is near its peak, because the Lyman-alpha forest is thin enough for QSO spectra to reveal the locations of the dominant metallic species, and because bright background QSOs are common. But a new UV-capable spectrograph in space will be required.