paper

The MOSDEF Survey: Dynamical and Baryonic Masses and Kinematic Structures of Star-Forming Galaxies at

arXiv:1511.03272 · doi:10.3847/0004-637X/819/1/80

Abstract

We present H gas kinematics for 178 star-forming galaxies at z~2 from the MOSFIRE Deep Evolution Field survey. We have developed models to interpret the kinematic measurements from fixed-angle multi-object spectroscopy, using structural parameters derived from CANDELS HST/F160W imaging. For 35 galaxies we measure resolved rotation with a median . We derive dynamical masses from the kinematics and sizes and compare them to baryonic masses, with gas masses estimated from dust-corrected H star formation rates (SFRs) and the Kennicutt-Schmidt relation. When assuming that galaxies with and without observed rotation have the same median , we find good agreement between the dynamical and baryonic masses, with a scatter of dex and a median offset of dex. This comparison implies a low dark matter fraction (8% within an effective radius) for a Chabrier initial mass function (IMF), and disfavors a Salpeter IMF. Moreover, the requirement that should be independent of inclination yields a median value of for galaxies without observed rotation. If instead we treat the galaxies without detected rotation as early-type galaxies, the masses are also in reasonable agreement (dex, dex). The inclusion of gas masses is critical in this comparison; if gas masses are excluded there is an increasing trend of with higher specific SFR (SSFR). Furthermore, we find indications that decreases with increasing H SSFR for our full sample, which may reflect disk settling. We also study the Tully-Fisher relation and find that at fixed stellar mass was higher at earlier times. At fixed baryonic mass, we observe the opposite trend. [abridged]

26 pages, 23 figures, accepted to ApJ

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