Artist's concept of a disky galaxy growing rapidly via narrow streams of cold gas. The gas provided by these filaments likely fuels the prodigious star formation activity detected in many of these young, disky, massive galaxies. This process, called "cold-mode accretion," has never been directly observed, but Weinzirl and Jogee's findings of a large percentage of massive, disky star-forming galaxies 10 billion years ago suggests that it played an important role in those galaxies' formation. Credit: ESA-AOES Medialab