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Wuyts, Stijn; Schreiber, Natascha M. Foerster; Wisnioski, Emily; Genzel, Reinhard; Burkert, Andreas; Bandara, Kaushala; Beifiori, Alessandra; Belli, Sirio; Bender, Ralf; Brammer, Gabriel B.; Chan, Jeffrey; Davies, Ric; Fossati, Matteo; Galametz, Audrey; Kulkarni, Sandesh K.; Lang, Philipp; Lutz, Dieter; Mendel, J. Trevor; Momcheva, Ivelina G.; Naab, Thorsten; Nelson, Erica J.; Saglia, Roberto P.; Seitz, Stella; Tacconi, Linda J.; Tadaki, Ken-ichi; Uebler, Hannah; Dokkum, Pieter G. van; Wilman, David J. and Wuyts, Eva (2016): KMOS3D: Dynamical constraints on the mass budget in early star-forming disks. In: Astrophysical Journal, Vol. 831, No. 2, 149

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We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at 0.6 < z < 2.6 to dynamically constrain their mass budget. Our sample consists of massive (greater than or similar to 10(9.8)M(circle dot)) galaxies with sizes R-e greater than or similar to 2 kpc. By contrasting the observed velocity and dispersion profiles with dynamical models, we find that on average the stellar content contributes 32(-7)(+8)% of the total dynamical mass, with a significant spread among galaxies (68th percentile range f(star) similar to 18%-62%). Including molecular gas as inferred from CO- and dust-based scaling relations, the estimated baryonic mass adds up to 56(-12)(+17%) of the total for the typical galaxy in our sample, reaching similar to 90% at z > 2. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at z > 2 being strongly baryon-dominated within R-e. Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High-Sigma(star) galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them.

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