Prospects for solving basic questions in galaxy evolution with a next generation radio telescope

Abstract

A Square Kilometer Array radio telescope will detect tens of thousands of galaxies per square degree in the 21cm emission line of neutral hydrogen. The telescope will be sensitive to ordinary galaxy populations at redshifts z>3 when the mass density in neutral gas greatly exceeded the mass in luminous stars. Spectroscopy in the HI line will trace the kinematics of evolving galactic potentials, as well as monitoring consumption of the fuel for star formation. The OH megamaser population may be a significant indicator of merger and interaction rates for galaxies over cosmic time. Spectroscopy of the redshifted HI and OH lines provides a major incentive for designing a large radio telescope with continuous frequency coverage below 2 GHz.