A dynamically cold disk galaxy in the early Universe

Abstract

The extreme astrophysical processes and conditions that characterize the early Universe are expected to result in young galaxies that are dynamically different from those observed today. This is because the strong effects associated with galaxy mergers and supernova explosions would lead to most young star-forming galaxies being dynamically hot, chaotic and strongly unstable. Here we report the presence of a dynamically cold, but highly star-forming, rotating disk in a galaxy at redshift ($z$) 4.2, when the Universe was just 1.4 billion years old. Galaxy SPT-S J041839-4751.9 is strongly gravitationally lensed by a foreground galaxy at $z=0.263$, and it is a typical dusty starburst, with global star-forming and dust properties that are in agreement with current numerical simulations and observations of its galaxy population. Interferometric imaging at a spatial resolution of about 60 pc reveals a ratio of rotational-to-random motions of $V/\sigma =9.7\pm 0.4$, which is at least four times larger than expected from any galaxy evolution model at this epoch, but similar to the ratios of spiral galaxies in the local Universe. We derive a rotation curve with the typical shape of nearby massive spiral galaxies, which demonstrates that at least some young galaxies are dynamically akin to those observed in the local Universe, and only weakly affected by extreme physical processes.

Published in Nature on 12 August 2020. The published version is available at http://www.nature.com/articles/s41586-020-2572-6

References in corpus (13)

• SPARC: Mass Models for 175 Disk Galaxies with Spitzer Photometry and Accurate Rotation Curves
• The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7<z<2.7
• Compaction and Quenching of High-z Galaxies in Cosmological Simulations: Blue and Red Nuggets
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• Bayesian Strong Gravitational-Lens Modeling on Adaptive Grids: Objective Detection of Mass Substructure in Galaxies
• The nature of the [CII] emission in dusty star-forming galaxies from the SPT survey
• The kiloparsec-scale star formation law at redshift 4: wide-spread, highly efficient star formation in the dust-obscured starburst galaxy GN20
• An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Near-infrared morphologies and stellar sizes
• LITTLE THINGS in 3D: robust determination of the circular velocity of dwarf irregular galaxies
• The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z~0.9 galaxies
• The nature of sub-millimeter and highly star-forming galaxies in the EAGLE simulation
• Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations
• A dense, solar metallicity ISM in the z=4.2 dusty star-forming galaxy SPT0418-47

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• Fast rotating and low-turbulence discs at $z\simeq 4.5$: Dynamical evidence of their evolution into local early-type galaxies
• Spiral morphology in an intensely star-forming disk galaxy more than 12 billion years ago
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XIII. Large-scale Feedback and Star Formation in a Low-Luminosity Quasar at z = 7.07 on the Local Black Hole to Host Mass Relation
• Dust temperature in ALMA $\hbox{[C $\scriptstyle\rm II $]}$-detected high-$z$ galaxies
• Cosmic-Ray Diffusion Suppression in Star-forming Regions Inhibits Clump Formation in Gas-rich Galaxies
• Unveiling the nature of 11 dusty star-forming galaxies at the peak of cosmic star formation history
• Auto-identification of unphysical source reconstructions in strong gravitational lens modelling