The WiggleZ Dark Energy Survey: High Resolution Kinematics of Luminous Star-Forming Galaxies

TL;DR

This study uses high-resolution integral field spectroscopy to analyze the kinematics of luminous star-forming galaxies at z~1.3, revealing evidence of ordered disk-like motion and gas dynamics that support cold flow accretion models.

Contribution

First detailed kinematic analysis of luminous star-forming galaxies at z~1.3 using adaptive optics-assisted IFS, showing evidence of disk-like rotation and gas inflows.

Findings

Evidence of ordered orbital motion consistent with disk models

Detection of high velocity dispersion in compact sources

Support for cold dense gas flow feeding star formation

Abstract

We report evidence of ordered orbital motion in luminous star-forming galaxies at z~1.3. We present integral field spectroscopy (IFS) observations, performed with the OH Suppressing InfraRed Imaging Spectrograph (OSIRIS) system, assisted by laser guide star adaptive optics on the Keck telescope, of 13 star-forming galaxies selected from the WiggleZ Dark Energy Survey. Selected via ultraviolet and [OII] emission, the large volume of the WiggleZ survey allows the selection of sources which have comparable intrinsic luminosity and stellar mass to IFS samples at z>2. Multiple 1-2 kpc size sub-components of emission, or 'clumps', are detected within the Halpha spatial emission which extends over 6-10 kpc in 4 galaxies, resolved compact emission (r<3 kpc) is detected in 5 galaxies, and extended regions of Halpha emission are observed in the remaining 4 galaxies. We discuss these data in the context of different snapshots in a merger sequence and/or the evolutionary stages of coalescence of star-forming regions in an unstable disk. We find evidence of ordered orbital motion in galaxies as expected from disk models and the highest values of velocity dispersion (\sigma>100 km/s) in the most compact sources. This unique data set reveals that the most luminous star-forming galaxies at z>1 are gaseous unstable disks indicating that a different mode of star formation could be feeding gas to galaxies at z>1, and lending support to theories of cold dense gas flows from the intergalactic medium.