Falling Outer Rotation Curves of Star-forming Galaxies at 0.6???z???2.6 Probed with KMOS3D and SINS/zC-SINF

摘要: We exploit the deep, resolved, Hα kinematic data from KMOS3D and SINS/zC-SINF surveys to examine largely unexplored outer-disk kinematics of star-forming galaxies (SFGs), out peak cosmic star formation. Our sample contains 101 SFGs, representative more massive () main sequence population at 0.6 ≤ z 2.6. Through a novel stacking approach, we are able constrain rotation curve extending ∼4 effective radii. This average exhibits significant drop in velocity beyond turnover, with slope units normalized coordinates V/V max R/R turn. result confirms that fall-off seen some individual is common feature our high-z disks. The outer strikingly deviates flat or mildly rising curves local spiral have similar masses. comparison models include baryons dark matter, demonstrate falling stacked consistent high mass fraction baryons, relative total matter halo (m d 0.05), combination sizeable level pressure support disk. These findings agree recent studies demonstrating disks strongly baryon-dominated within disk scale, furthermore suggest gradients caused by large, turbulent gas motions present even their results independent model assumptions, such as presence stellar bulges, effect adiabatic contraction, variations concentration.