IMAGES. I. Strong evolution of galaxy kinematics since z = 1

Abstract

Nearly half the stellar mass of present-day spiral galaxies has formed since z = 1, and galaxy kinematics is an ideal tool to identify the underlying mechanisms responsible for the galaxy mass assembly since that epoch. Here, we present the first results of the ESO large program, "IMAGES", which aims at obtaining robust measurements of the kinematics of distant galaxies using the multi-IFU mode of GIRAFFE on the VLT. 3D spectroscopy is essential to robustly measure the often distorted kinematics of distant galaxies (e.g., Flores et al. 2006, A&A, 455, 107). We derive the velocity fields and σ-maps of 36 galaxies at 0.4 < z < 0. 10 M emission line galaxies in this redshift range, and are largely unaffected by cosmic variance. Taking into account all galaxies -with or without emission lines -in that redshift range, we find that at least 41 ± 7% of them have anomalous kinematics, i.e., they are not dynamically relaxed. This includes 26 ± 7% of distant galaxies with complex kinematics, i.e., they are not simply pressure or rotationally supported. Our result implies that galaxy kinematics are among the most rapidly evolving properties, because locally, only a few percent of the galaxies in this mass range have complex kinematics. It is well-established that galaxies undergoing a merger have complex large-scale motions and thus are likely responsible for the strong evolution of the galaxy kinematics that we observe.

The Dawes Review 1: Kinematic Studies of Star-Forming Galaxies Across Cosmic Time

“…Comparing the tabulated properties of the objects in common, I note that Miller et al report masses 0.8-0.9 dex less for these same three objects, with velocity agreement for two. These particular CK objects lie fairly close to the IMAGES Tully-Fisher relationship compared to other CK objects, and all show distinct velocity shears in the maps of Yang et al (2008) and so may be misclassified. They may not be comparable with the other CK objects; a proper comparison would require more overlap.…”

A giant bar induced by a merger event at z = 0.4?

“…J033239.72-275154.7 was first presented by Yang et al (2008). Table 1 summarizes its overall properties, including photometry, morphological parameters, and kinematical measurements (provided by the IMAGES data base that can be retrieved from Yang et al 2008;Neichel et al 2008;Puech et al 2008).…”

“…Table 1 summarizes its overall properties, including photometry, morphological parameters, and kinematical measurements (provided by the IMAGES data base that can be retrieved from Yang et al 2008;Neichel et al 2008;Puech et al 2008). This object has a stellar mass of 2.0 × 10 10 M , a K-band magnitude of M K = −20.94, and displays a peculiar morphology and kinematics.…”

“…The pixel scale is 0.52 arcsec and the full width half maximum spectral resolution is 23 km s −1 . Details of the GIRAFFE instruments can be found in Flores et al (2006) and Yang et al (2008). The small VF amplitude is dominated by the two star-bursting clumps and by the blue arm/giant tidal tail.…”

“…initial orbital configuration and mass ratio of the system) and possible fate. This work is a subsidiary project of a VLT large program entitled IMAGES ("Intermediate-MAss Galaxy Evolution Sequence", Yang et al 2008), which is gathering high quality kinematics for a representative sample of ∼100 massive galaxies at z = 0.4-0.75 and with M J (AB) ≤ −20.3. Using the GIRAFFE spectrograph at the VLT, the kinematic properties of 65 of these galaxies, for instance J033239.72-275154.7, have been derived.…”