The KMOS3D Survey: Rotating Compact Star-forming Galaxies and the Decomposition of Integrated Line Widths

Wisnioski, E.; Mendel, J.T.; Förster Schreiber, N.M.; Genzel, R.; Wilman, D.; Wuyts, S.; Belli, S.; Beifiori, A.; Bender, R.; Brammer, G.; Chan, J.; Davies, R.I.; Davies, R.L.; Fabricius, M.; Fossati, M.; Galametz, A.; Lang, P.; Lutz, D.; Nelson, E.J.; Momcheva, I.; Rosario, D.; Saglia, R.; Tacconi, L.J.; Tadaki, K.; Übler, H.; van Dokkum, P.G.

Abstract

Using integral field spectroscopy, we investigate the kinematic properties of 35 massive centrally dense and compact star-forming galaxies (SFGs; $\mathrm{log}{\overline{M}}_{* }[{M}_{\odot }]=11.1$, $\mathrm{log}({{\rm{\Sigma }}}_{1\mathrm{kpc}}[{M}_{\odot }\,{\mathrm{kpc}}^{-2}])\gt 9.5$, $\mathrm{log}({M}_{* }/{r}_{e}^{1.5}[{M}_{\odot }\,{\mathrm{kpc}}^{-1.5}])\gt 10.3$) at z ~ 0.7–3.7 within the KMOS3D survey. We spatially resolve 23 compact SFGs and find that the majority are dominated by rotational motions with velocities ranging from 95 to 500 km s−1. The range of rotation velocities is reflected in a similar range of integrated Hα line widths, 75–400 km s−1, consistent with the kinematic properties of mass-matched extended galaxies from the full KMOS3D sample. The fraction of compact SFGs that are classified as "rotation-dominated" or "disklike" also mirrors the fractions of the full KMOS3D sample. We show that integrated line-of-sight gas velocity dispersions from KMOS3D are best approximated by a linear combination of their rotation and turbulent velocities with a lesser but still significant contribution from galactic-scale winds. The Hα exponential disk sizes of compact SFGs are, on average, 2.5 ± 0.2 kpc, 1–2× the continuum sizes, in agreement with previous work. The compact SFGs have a 1.4× higher active galactic nucleus (AGN) incidence than the full KMOS3D sample at fixed stellar mass with an average AGN fraction of 76%. Given their high and centrally concentrated stellar masses, as well as stellar-to-dynamical mass ratios close to unity, the compact SFGs are likely to have low molecular gas fractions and to quench on a short timescale unless replenished with inflowing gas. The rotation in these compact systems suggests that their direct descendants are rotating passive galaxies.

Citation

Wisnioski, E., Mendel, J., Förster Schreiber, N., Genzel, R., Wilman, D., Wuyts, S., …van Dokkum, P. (2018). The KMOS3D Survey: Rotating Compact Star-forming Galaxies and the Decomposition of Integrated Line Widths. Astrophysical Journal, 855(2), Article 97. https://doi.org/10.3847/1538-4357/aab097

• Journal Article Type: Article
• Acceptance Date: Feb 16, 2018
• Online Publication Date: Mar 12, 2018
• Publication Date: Mar 12, 2018
• Deposit Date: Apr 9, 2018
• Publicly Available Date: Apr 9, 2018
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 855
• Issue: 2
• Article Number: 97
• DOI: https://doi.org/10.3847/1538-4357/aab097
• Public URL: https://durham-repository.worktribe.com/output/1335273