KINEMATIC DOWNSIZING AT z ∼ 2

• Published in: The Astrophysical journal Vol. 830; no. 1; pp. 14 - 33
• Main Authors: Simons, Raymond C., Kassin, Susan A., Trump, Jonathan R., Weiner, Benjamin J., Heckman, Timothy M., Barro, Guillermo, Koo, David C., Guo, Yicheng, Pacifici, Camilla, Koekemoer, Anton, Stephens, Andrew W.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 10.10.2016; IOP Publishing
• Subjects: Assembly; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Disks; Dispersion; DISPERSIONS; Disruption; Downsizing; EMISSION; Emission lines; Emission measurements; GALACTIC EVOLUTION; Galactic rotation; GALAXIES; galaxies: evolution; galaxies: formation; galaxies: fundamental parameters; galaxies: kinematics and dynamics; Kinematics; MASS; Massive stars; Polls & surveys; ROTATION; Space telescopes; Star formation; STARS; Stellar mass; VELOCITY
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/830/1/14

ABSTRACT We present results from a survey of the internal kinematics of 49 star-forming galaxies at in the CANDELS fields with the Keck/MOSFIRE spectrograph, Survey in the near-Infrared of Galaxies with Multiple position Angles (SIGMA). Kinematics (rotation velocity Vrot and gas velocity dispersion ) are measured from nebular emission lines which trace the hot ionized gas surrounding star-forming regions. We find that by , massive star-forming galaxies ( ) have assembled primitive disks: their kinematics are dominated by rotation, they are consistent with a marginally stable disk model, and they form a Tully-Fisher relation. These massive galaxies have values of that are factors of 2-5 lower than local well-ordered galaxies at similar masses. Such results are consistent with findings by other studies. We find that low-mass galaxies ( ) at this epoch are still in the early stages of disk assembly: their kinematics are often dominated by gas velocity dispersion and they fall from the Tully-Fisher relation to significantly low values of Vrot. This "kinematic downsizing" implies that the process(es) responsible for disrupting disks at have a stronger effect and/or are more active in low-mass systems. In conclusion, we find that the period of rapid stellar mass growth at is coincident with the nascent assembly of low-mass disks and the assembly and settling of high-mass disks.