His research focuses on galaxy formation in its most active phase at the early universe, using analytic models and computer simulations. He studies how continuous streams of cold gas and merging galaxies from the cosmic web lead to star-forming disks and drive violent gravitational disk instability, and how this instability leads to the formation of compact spheroidal galactic components with central massive black holes. His recent work focuses on the formation of the first galaxies as observed by the James Webb Space Telescope, proposing a unique phase of feedback-free starbursts in the early Universe.