Regular rotation and low turbulence in a diverse sample of z ~ 4.5 galaxies observed with ALMA
| Autor: | Roman-Oliveira, Fernanda, Fraternali, Filippo, Rizzo, Francesca |
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| Rok vydání: | 2023 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stad530 |
| Popis: | The discovery of galaxies with regularly rotating discs at redshifts $\geq$ 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 $\sim$ 4.5 observed with ALMA in the [CII] 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 while the gas velocity dispersions, averaged across the discs, are between 49 and 75 km/s. 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. Comment: 20 pages, 9 figures, MNRAS accepted |
| Databáze: | arXiv |
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