Understanding the diversity of galaxy morphology in the era of large spectroscopic surveys

ongoing

Galaxies are the building blocks of structure in the Universe; this proposal seeks to understand how their shapes, colours and dynamics are determined. For example, what happened in the history of some galaxies to transform them into passive ellipticals while others, seemingly of the same mass and in the same environment, are star-forming spirals? Even such a basic question about the link between morphology and star formation has not yet been answered, revealing our theories of galaxy formation are inadequate. This is a major concern in an era where understanding the shapes of galaxies and how they relate to the underlying dark matter is essential for progress in precision cosmology. This project will build the missing link between the history of a galaxy and its observational properties (i.e. between cause and effect) by using numerical simulations. Current research in this area rightly gives significant attention to the crucial problem of how feedback – energy input from supernovae, active galactic nuclei, and more – affect observable properties. But as well as investigating this avenue, GM Galaxies will uniquely make use of my new technique (“genetic modification”) to systematically investigate the role of the galaxy’s merging and accretion history at high resolution. To distinguish the fingerprints of history from the effects of feedback, we will compare to rich new data from integral field unit surveys; these reveal, for example, galactic metallicity and velocity maps. My pilot study for this project shows that such measures of a galaxy disambiguate between alternative formation routes to galaxies which would appear similar by photometric measures alone. Similarly, we will make predictions for the observable properties of the gas reservoir surrounding galaxies and for integral field observations at high redshift. In this way we will make a predictive account of how galactic structure is determined by the interaction of the accretion history with feedback.