Abstract
We present spatially resolved stellar kinematic maps, for the first time, for
a sample of 17 intermediate redshift galaxies (0.2 < z < 0.8). We used deep
MUSE/VLT integral field spectroscopic observations in the Hubble Deep Field
South (HDFS) and Hubble Ultra Deep Field (HUDF), resulting from ~30h
integration time per field, each covering 1'x1' field of view, with ~0.65"
spatial resolution. We selected all galaxies brighter than 25mag in the I band
and for which the stellar continuum is detected over an area that is at least
two times larger than the spatial resolution. The resulting sample contains
mostly late-type disk, main-sequence star-forming galaxies with 10^8.5 -
10^10.5 Msun. Using a full-spectrum fitting technique, we derive
two-dimensional maps of the stellar and gas kinematics, including the radial
velocity V and velocity dispersion sigma. We find that most galaxies in the
sample are consistent with having rotating stellar disks with roughly constant
velocity dispersions and that the Vrms=sqrtV^2+sigma^2 of the gas and stars,
a scaling proxy for the galaxy gravitational potential, compare well to each
other. These spatially resolved observations of intermediate redshift galaxies
suggest that the regular stellar kinematics of disk galaxies that is observed
in the local Universe was already in place 4 - 7 Gyr ago and that their gas
kinematics traces the gravitational potential of the galaxy, thus is not
dominated by shocks and turbulent motions. Finally, we build dynamical
axisymmetric Jeans models constrained by the derived stellar kinematics for two
specific galaxies and derive their dynamical masses. These are in good
agreement (within 25%) with those derived from simple exponential disk models
based on the gas kinematics. The obtained mass-to-light ratios hint towards
dark matter dominated systems within a few effective radii.
Description
[1710.07694] The MUSE Hubble Ultra Deep Field Survey: V. Spatially resolved stellar kinematics of galaxies at redshift $0.2\lesssim z \lesssim 0.8$
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