Star formation on kpc-scales from redshift 0.1 to 1.5
Morphologies of star-forming galaxies at z>1 are typically irregular containing a handful of dominant bright regions. Recent observational evidence suggest that many of these galaxies are governed by disc-like rotation. Using Halpha galaxy kinematics from OSIRIS+LGSAO we find that within z~1 turbulent discs star-forming regions have average sizes of 1.5 kpc and average Jeans masses of 4.2x10^9 \Msun, in total accounting for 20-30% of the stellar mass of the discs. These findings lend observational support to models that predict larger star-forming regions will form as a result of higher disc velocity dispersions driven-up by cosmological gas accretion. As a consequence of the changes in global environment, it may be predicted that star-forming regions at high redshift should not resemble star-forming regions locally. Yet despite the increased sizes and dispersions, high-z star-forming regions and HII regions are found to follow tight scaling relations over the range z=0-2 for Halpha size, velocity dispersion, luminosity and mass when comparing >2000 HII regions locally and 30 regions at z>1. While the turbulence of discs may have important implications for the size and luminosity of regions which form within them, the same processes likely govern their formation from high redshift to the current epoch. We are now able to test this conclusion with first results from a new sample of z=0.1-0.2 highly star-forming turbulent galaxies from the Sloan Digital Sky Survey.
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Max Planck Institute for Extraterrestrial Physics
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