TY - JOUR
T1 - Falling Outer Rotation Curves of Star-forming Galaxies at 0.6 ≲ z ≲ 2.6 Probed with KMOS3D and SINS/zC-SINF
AU - Lang, Philipp
AU - Förster Schreiber, Natascha M.
AU - Genzel, Reinhard
AU - Wuyts, Stijn
AU - Wisnioski, Emily
AU - Beifiori, Alessandra
AU - Belli, Sirio
AU - Bender, Ralf
AU - Brammer, Gabe
AU - Burkert, Andreas
AU - Chan, Jeffrey
AU - Davies, Ric
AU - Fossati, Matteo
AU - Galametz, Audrey
AU - Kulkarni, Sandesh K.
AU - Lutz, Dieter
AU - Mendel, J. Trevor
AU - Momcheva, Ivelina G.
AU - Naab, Thorsten
AU - Nelson, Erica J.
AU - Saglia, Roberto P.
AU - Seitz, Stella
AU - Tacchella, Sandro
AU - Tacconi, Linda J.
AU - Tadaki, Ken Ichi
AU - Übler, Hannah
AU - Van Dokkum, Pieter G.
AU - Wilman, David J.
PY - 2017/5/12
Y1 - 2017/5/12
N2 - 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.
AB - 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.
KW - galaxies: high-redshift
KW - galaxies: kinematics and dynamics
KW - galaxies: structure
UR - http://www.scopus.com/inward/record.url?scp=85019956631&partnerID=8YFLogxK
UR - http://dx.doi.org/10.3847/1538-4357/aa6d82
U2 - 10.3847/1538-4357/aa6d82
DO - 10.3847/1538-4357/aa6d82
M3 - Article
AN - SCOPUS:85019956631
SN - 0004-637X
VL - 840
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 92
ER -