Elizabeth Tasker


My research focusses on exploring this question through high resolution simulations of isolated (single) disc galaxies. Since some of our best observational data is from our own galaxy, I use the Milky Way as a template for models that extend down to resolutions of 1 pc. At this level of detail, it is possible to model the formation and evolution of the Giant Molecular Clouds; cold, dense structures in which the majority of the galaxy’s star formation occurs. Since the entire galaxy disc is included in the simulation, we can explore how these clouds interact with the galaxy’s global environment (for example, the large-scale structure, potential and disc shear) and each other as their stellar populations form.

Of particular interest is how feedback from stars affects the evolution of their gaseous nurseries. I am currently working on models to include localised feedback such as supernovae and radiation driven winds as well as diffuse feedback from photoelectric heating by dust grains. By comparing discs with different forms of feedback, I hope to isolate the key forces governing the star forming environment and discover what role the galaxy’s global structure plays in its star formation.

The numerical code I use is Enzo; a 3-dimensional adaptive mesh refinement hydrodynamics (AMR) code. The AMR technique is particularly strong at resolving shocks and multiphase fluids which are important factors in my research areas. Enzo has an active developer team and Enzo 2.0 was released last summer. More details about Enzo, including how to get a copy of the code, can be found from the webpages here. How Enzo compares with other astrophysical codes in a set of standard tests can be seen in a code comparison project I led, which has a website and associated journal paper.

Top right image shows the peculiar velocity (gas velocity minus the circular motion around the disc) in a simulation that includes stellar feedback from supernovae explosions. White regions indicate strong outflows with speeds over 100 km/s while red regions have velocities around 1 km/s. The image directly above shows a close up of a cloud forming along a filament in the disc, with the AMR grids displayed over the colours showing surface density. Above that is a lantern from a restaurant in Japan!


All galaxies (we believe) have them, but what determines how they form and how does their birth, life and death affect the galaxy?