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KINEMATIC DOWNSIZING AT z similar to 2

We present results from a survey of the internal kinematics of 49 star-forming galaxies at z similar to 2 in the CANDELS fields with the Keck/MOSFIRE spectrograph, Survey in the near-Infrared of Galaxies with Multiple position Angles (SIGMA). Kinematics (rotation velocity V-rot and gas velocity dispersion sg) are measured from nebular emission lines which trace the hot ionized gas surrounding star-forming regions. We find that by z similar to 2, massive star-forming galaxies (log M-*/M-circle dot less than or similar to 10.2) 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 V-rot sg 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 (log M-*/M-circle dot less than or similar to 10.2) 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 V-rot. This "kinematic downsizing" implies that the process(es) responsible for disrupting disks at z similar to 2 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 z similar to 2 is coincident with the nascent assembly of low-mass disks and the assembly and settling of high-mass disks.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624072
Date03 October 2016
CreatorsSimons, 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.
ContributorsUniv Arizona, Steward Observ
PublisherIOP PUBLISHING LTD
Source SetsUniversity of Arizona
LanguageEnglish
Detected LanguageEnglish
TypeArticle
Rights© 2016. The American Astronomical Society. All rights reserved.
Relationhttp://stacks.iop.org/0004-637X/830/i=1/a=14?key=crossref.fff89233ad01a38d0de63e5e715b4ecc

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