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Colloquium: The fast rotating and not-so-turbulent discs of high-redshift galaxies

Submitter: Filippo Fraternali
Description: After decades of being mostly confined to the local Universe, the study of gas dynamics in galaxies, via a variety of emission-line gas tracers, has now become a key tool of investigation across cosmic time.

The rotation of the gas allows us to trace the distribution of matter, quantify the mass and shape of the dark matter halos and to study galaxy scaling relations. In contrast, gas turbulence reveals the effects of stellar feedback and disc instabilities and provides clues on the formation of the stellar thin/thick discs.

In this talk, I will present results on high-z rotation curves and velocity dispersions obtained through 3D reconstruction techniques of the emission-line datacubes. After briefly discussing results at z~1, I will focus on ALMA observations of starburst galaxies at z~4 observed in the [CII] emission line. These reveal fast rotation and surprisingly low velocity dispersions leading to typical V/sigma values of order 10.

These results pose new challenges to our understanding of galaxy formation at early times.
Copyright: Filippo Fraternali
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