Resolution and Kinematics of Molecular Gas Surrounding the Cloverleaf Quasar at z=2.6 Using the Gravitational Lens

Gravitational lenses have long been advertised as primitive telescopes, capable of magnifying cosmologically distant sources (Zwicky 1937). In this Letter, we present new 0''.9 resolution CO (7-6) observations of the z=2.56 Cloverleaf quasar (H 1413+117) and spatially resolved images. By modeling the gravitational lens, we infer a size scale of 0''.3 (~1 kpc) for the molecular gas structure surrounding the quasar, and the gas has a kinematic structure roughly consistent with a rotating disk. The observed properties of the CO emitting gas are similar to the nuclear starburst complexes found in the infrared luminous galaxies in the local universe, and metal enrichment by vigorous star formation within this massive nuclear gas complex can explain the abundance of carbon and oxygen in the interstellar medium of this system observed when the universe was only a few billion years old. Obtaining corresponding details in an unlensed object at similar distances would be well beyond the reach of current instruments, and this study highlights the less exploited yet powerful use of a gravitational lens as a natural telescope.