The evolution of the dynamics and chemistry of star forming galaxies across cosmic time

The Hubble-Sequence of galaxy morphologies remains one of the defining characteristics of galaxies, and provides one of the key constraints that galaxy formation models strive to reproduce.

Dynamical studies of local galaxies have shown that the Hubble Sequence of galaxy morphologies follows a sequence of increasing angular momentum at a fixed mass. In the cold dark matter paradigm, galaxies form at the centres of dark matter halos. As the gas collapses within the dark halo, the baryons can both lose and gain angular momentum.

If the angular momentum of the baryons is (weakly) conserved during collapse, they will form a centrifugally supported disk with an exponential light profile (e.g. a spiral galaxy).

If the angular momentum is redistributed (due to mergers and/or strong outflows), the morphology of the galaxy is more likely to represent a early-type or elliptical galaxy.

While the role of angular momentum in locating galaxies along the Hubble-Sequence is well constrained at z=0, how the baryonic angular momentum evolves with cosmic time, and results in the emergence of the Hubble-Sequence at high redshift has not been established.

Observations from the Hubble Space Telescope (HST) have shown that the transition from a galaxy population dominated by clumpy, irregular morphologies to smoother, disk-like galaxies appears to occur around z=1.5, and this has been heralded as the epoch when the Hubble Sequence "emerged", In this project, we will conduct an observational program to measure the gas properties and star formation properties in a sample of galaxies at z=1-3 (i.e. lookback times of 7-10 billion years).

We will measure the role of baryons, dark matter, disk turbulence, and gas inflows and outflows in defining the formation of the galaxies. We will address the following inter-related questions: 1. How does the angular momentum of high-redshift galaxy disks result in the emergence of the Hubble-Sequence? 2.

How do the dark matter fractions of galaxies evolve with mass and redshift? 3. What physical processes control the formation and evolution of star-forming regions and the gas disk? 4. Where do star-forming winds originate and how much mass and angular momentum do they carry? This is an observationally-driven PhD project.

The successful student will use a range of observational facilities, potentially including travel to Chile, Hawaii or Europe to obtain data for their thesis.

The PhD will provide training in the reduction and analysis of imaging, integral field spectroscopy and interferometry There will also be opportunities to relate the observational results to theoretical models being developed at Durham.