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

Philipp Lang, Natascha M. Förster Schreiber, Reinhard Genzel, Stijn Wuyts, Emily Wisnioski, Alessandra Beifiori, Sirio Belli, Ralf Bender, Gabe Brammer, Andreas Burkert, Jeffrey Chan, Ric Davies, Matteo Fossati, Audrey Galametz, Sandesh K. Kulkarni, Dieter Lutz, J. Trevor Mendel, Ivelina G. Momcheva, Thorsten Naab, Erica J. NelsonRoberto P. Saglia, Stella Seitz, Sandro Tacchella, Linda J. Tacconi, Ken Ichi Tadaki, Hannah Übler, Pieter G. Van Dokkum, David J. Wilman

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Abstract

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

Original languageEnglish
Article number92
JournalAstrophysical Journal
Volume840
Issue number2
DOIs
Publication statusPublished - 12 May 2017

Keywords

  • galaxies: high-redshift
  • galaxies: kinematics and dynamics
  • galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Lang, P., Förster Schreiber, N. M., Genzel, R., Wuyts, S., Wisnioski, E., Beifiori, A., Belli, S., Bender, R., Brammer, G., Burkert, A., Chan, J., Davies, R., Fossati, M., Galametz, A., Kulkarni, S. K., Lutz, D., Mendel, J. T., Momcheva, I. G., Naab, T., ... Wilman, D. J. (2017). Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF. Astrophysical Journal, 840(2), [92]. https://doi.org/10.3847/1538-4357/aa6d82