Research Interests

Above: a very brief (1-minute) video description of my research. This video was entered in
NSERC's 2016 "Science, Action!" video contest (thanks to Trent student Matthew Hayes
for creating this video).

My primary research interests lie in the study of galaxy evolution, with a particular focus on the role of galaxy-galaxy interactions and mergers. My earlier work in this area developed the use of close galaxy pairs as a probe of the galaxy merger rate, in both the nearby universe (e.g., Patton et al. 2000; Patton & Atfield 2008) and in the higher redshift (more distant) universe (e.g., Patton et al. 2002, Lin et al. 2004, 2008).   In recent years, my efforts have shifted to the properties of interacting and merging galaxies, using both observations and simulations. An overview of this research is given below.

The Properties of Interacting and Merging Galaxies in SDSS

My collaborators and I have used the Sloan Digital Sky Survey (SDSS) to show that galaxies which have close companions have enhanced star formation rates, higher asymetries, diluted metallicities, bluer colours and higher active galactic nucleus fractions than galaxies which do not have close companions (e.g., Patton et al. 2011, Ellison et al. 2011, Scudder et al. 2012, Patton et al. 2013, Satyapal et al. 2014). Patton et al. 2016). We have found similar results in galaxies which have recently merged (Ellison et al. 2013; Ellison et al. 2015). Sample images of these pairs and post-mergers are shown below.

Left: A mosaic of close galaxy pairs from SDSS (Patton et al. 2011).
Right: A mosaic of post-merger galaxies from SDSS (Ellison et al. 2013).

Merger Simulations

We have also compared our observational findings with state-of-the-art merger simulations ( Patton et al. 2013; Moreno et al. 2015), A movie showing the output from some of these simulations is shown below. We are now hard at work on creating a new and improved merger suite.

Above: High resolution simulations of three of the merger trajectories from Patton et al. (2013).
The upper panels show the gas density. The lower left panel plots 3D pair separation vs. time.
The lower right panel shows star formation rate enhancement vs. separation.
Click on the image to play the movie!

TiNy Titans (TNT): A Study of Interacting Dwarf Galaxies

I am now involved in a new effort to explore the role of interactions between the least luminous (dwarf) galaxies in the universe. This project, dubbed TiNy Titans (TNT), is being undertaken in collaboration with researchers at the University of Virginia, the University of Arizona, Columbia University and the University of Florida. The observational part of this project began with the selection of dwarf pairs from SDSS, and we continue to acquire follow-up multi-wavelength observations of these pairs using various world-class observatories. We are comparing these data with state-of-the-art simulations from the Illustris Project. We have recently published our first four TNT papers (Stierwalt et al. 2015, Pearson et al. 2016, Stierwalt et al. 2017, Privon et al. 2017).  

Left: A mosaic of dwarf galaxy pairs from TNT (Stierwalt et al. 2015).
Right: Evidence of enhanced star formation rates in TNT dwarf pairs (Stierwalt et al. 2015).

For additional information, please see my List of Publications or contact me by email at

Dave Patton