Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 521, Issue 1, Pages 1045-1065Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stad530
Keywords
galaxies: evolution; galaxies: high-redshift; galaxies: kinematics and dynamics; submillimetre: galaxies
Categories
Ask authors/readers for more resources
The discovery of galaxies with regularly rotating discs at redshifts > 4 challenges existing galaxy formation models, which predict chaotic gas kinematics in the early Universe due to gas accretion, mergers, and efficient feedback. Studies of five highly resolved galaxies at z similar to 4.5 using ALMA observations of the [ C II ] 158 μm emission line reveal that four of them are rotating discs, indicating that early disc formation with dominant rotation is present across different galaxy types.
The discovery of galaxies with re gularly rotating discs at redshifts > 4 has been a puzzling challenge to galaxy formation models that tend to predict chaotic gas kinematics in the early Universe as a consequence of gas accretion, mergers, and efficient feedback. In this work, we investigated the kinematics of five highly resolved galaxies at z similar to 4.5 observed with ALMA in the [ C II ] 158 mu m emission line. The sample is diverse: AzTEC1 (starburst galaxy), BRI1335-0417 (starburst and quasar host galaxy), J081740 (normal star-forming galaxy), and SGP38326 (two starburst galaxies in a group). The five galaxies show velocity gradients, but four were found to be rotating discs, while the remaining, AzTEC1, is likely a merger. We studied the gas kinematics of the discs using 3DBAROLO and found that they rotate with maximum rotation velocities between 198 and 562 km s -1, while the gas velocity dispersions, averaged across the discs, are between 49 and 75 km s -1. The rotation curves are generally flat and the galaxies have ratios of ordered-to-random motion (V/ sigma) between 2.7 and 9.8. We present CANNUBI, an algorithm for fitting the disc geometry of rotating discs in 3D emission-line observations prior to modelling the kinematics, with which we find indications that these discs may have thicknesses of the order of 1 kpc. This study shows that early disc formation with a clear dominance of rotation with respect to turbulent motions is present across a variety of galaxy types.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available