ITC Colloquium - Andreas Burkert (Munich Univ Observatory)


Thursday, January 26, 2017, 11:00am to 12:00pm



"The origin and dynamics of high-redshift disk galaxies"

The redshift two Universe is one of the most interesting epochs of galaxy evolution. It is the era with the peak of the cosmic star formation rate. Between redshift 3 and 1 the total stellar mass density in galaxies increased from 15% to 70%. It is also the time of rapid galaxy assembly and the epoch where galaxy morphology was determined.

I will summarize new observations of the SINS survey, a Spectroscopic Imaging survey of z=2 galaxies in the near infrared with SINFONI. This survey has opened a fascinating window into early galaxy evolution. The SINS data show a diversity of galactic systems at redshift 2 with physical properties that are unparalleled in the z=0 Universe. Gas-rich, extended, fast rotating and highly turbulent disks have been found with  star formation rates that are a factor of 10 to 100 larger than in present-day Milky-Way type galaxies. Kpc-sized, massive gas clumps dominate the appearance of these galaxies. These giant clumps are considered to represent the progenitors of present-day globular clusters. They could provide the seeds for supermassive black holes and they might lead to the formation of young bulges in the centers of their galaxies.

These fascinating and puzzling observations will be confronted with theoretical ideas and numerical simulations of gas-rich galactic disk evolution. I will argue that the high-redshift star-forming galaxies have similar angular momentum distribution as their low-redshift counterparts. The specific angular momentum distribution is in excellent agreement with the dark halo spin parameter distribution, predicted by cold dark matter simulations. This indicates that the morphological difference  between fast rotating disk galaxies and slowly rotating ellipticals is not driven by a difference in their specific angular momentum distribution. I then propose that the high-redshift galaxies, like present-day disks, are in a self-organized equilibrium state with their observed extreme properties emerging naturally from self-regulated galactic evolution, controlled by gas inflow from the cosmic web.

See also: Colloquium, 2016-17