Dr David R Law (UCLA)

"Kiloparsec-Scale Kinematics in High-Redshift Star-Forming Galaxies"

I discuss the results of a multi-year Keck/LGSAO survey of the internal kinematics of rapidly star-forming galaxies at redshift z ~ 2 - 3 as traced by nebular line emission on angular scales ~ 0.1 arcsec. At most 5 of the 13 best-detected galaxies have spatially resolved velocity gradients consistent with rotation, while the remaining galaxies have relatively featureless or irregular velocity fields. All of our galaxies exhibit high local velocity dispersions ~ 60 - 100 km/s, suggesting that even for those galaxies with clear velocity gradients rotation about a preferred kinematic axis may not be the dominant means of physical support. The dynamical importance of cold gas appears to be the primary factor governing the observed kinematics, and I discuss possible mechanisms for the accretion of low angular-momentum gas and the early formation of quasi-spheroidal systems.