The MUSE Hubble Ultra Deep Field Survey

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 ≈ 30 h integration time per field, each covering 1 × 1 field of view, with ≈ 0 . 65 spatial resolution. We selected all galaxies brighter than 25 mag 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 M M * 10 10.5 M . 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 σ. We find that most galaxies in the sample are consistent with having rotating stellar disks with roughly constant velocity dispersions and that the second order velocity moments V rms = √ V 2 + σ 2 of the gas and stars, a scaling proxy for the galaxy gravitational potential, compare well to each other. These spatially resolved observations of the stellar kinematics 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.

First results from the TNG50 simulation: the evolution of stellar and gaseous discs across cosmic time

“…While studies of the stellar kinematics of star-forming galaxies are now common in the local Universe (e.g. with integral field spectroscopy data from SAMI, MANGA, and CALIFA), this is not yet viable at higher redshifts (although see Guérou et al 2017).…”

Single metal-poor ultra compact dwarf galaxy at one kiloparsec distance from the low-mass elliptical galaxy FCC 47

“…Being a low-mass system, fitting the UCD's velocity dispersion from the background-subtracted spectrum is challenging due to the low S/N and the limited spectral resolution of the MUSE instrument. As the instrumental resolution is highest around the Calcium II triplet (CaT) at ∼8500 Å (Guérou et al 2017), we determine the velocity dispersion in a narrow wavelength range from 8420 to 8800 Å. For this fit, we use the Calcium II Triplet library (Cenarro et al 2001), consisting of ∼ 700 stars in a wavelength range between 8350 -9020 Å at 1.5 Å spectral resolution.…”

“…For this fit, we use the Calcium II Triplet library (Cenarro et al 2001), consisting of ∼ 700 stars in a wavelength range between 8350 -9020 Å at 1.5 Å spectral resolution. The higher resolution is relevant because the MUSE resolution as measured by Guérou et al (2017) is below the resolution of the MILES templates of 2.5 Å in the CaT region. This would require us to degrade the MUSE spectrum in this wavelength range and would further complicate the velocity dispersion measurement.…”

The MUSE Hubble Ultra Deep Field Survey

“…The properties of CIII] emitters as Lyα alternative for redshift confirmation of high-z galaxies are discussed in Paper IV (Maseda et al 2017). In Paper V (Guérou et al 2017) we obtain spatially resolved stellar kinematics of galaxies at z ≈ 0.2-0.8 and compare their kinematical properties with those inferred from gas kinematics. The faint end of the Lyα luminosity function and its implication for reionization are presented in Paper VI (Drake et al 2017b).…”