Cam Lawlor-Forsyth

University of Waterloo

Cam is a doctoral candidate at the University of Waterloo and the Waterloo Centre for Astrophysics working with Michael Balogh. His research focuses on understanding the shutdown of star formation within galaxies and the different processes that can contribute to this shutdown, which is known as quenching. Cam obtained his bachelor’s and master’s from the University of Manitoba, working with Chris O’Dea and Stefi Baum, with a master’s thesis on the environments of active galactic nuclei in the Close Active Galactic Nuclei Reference Survey.

Galaxies broadly exist as either actively star forming, or as passive quiescent galaxies with inactive star formation. In addition, galaxies in dense environments like clusters of galaxies experience different physical effects than galaxies that are in sparsely populated fields. Cam investigates how the star formation within galaxies is quenched by using spatially-resolved measurements of star formation, in both large cosmological magnetohydrodynamical simulations like IllustrisTNG, as well as real world observations, like those available with programs such as the Hubble Frontier Fields. Cam’s doctoral work has shown that a certain combination of these spatially-resolved measurements can classify simulated galaxies based on their most likely quenching mechanism, where the quenching mechanism is correlated with the large-scale environment, and that this information can also be recovered when creating deep, spatially-resolved mock observations. These mock observations are based on real observations that will be available with the Nancy Grace Roman space telescope, as well as the Canadian-led CASTOR space telescope, a collaboration that Cam is a part of. These results will be presented in a series of papers that will be submitted shortly.

The ultimate goal of Cam’s research is to better understand the complex physical processes that drive galaxy evolution in different environments using spatially-resolved observations which provide additional information compared to simple integrated quantities. A figure from Cam’s work is included below which demonstrates the power of spatially-resolved measurements applied to a simulated galaxy from IllustrisTNG. You can learn more about Cam’s research by watching his research video from the Waterloo Centre for Astrophysics: https://youtu.be/V_t0ogz0nW8

A log(M∗/M⊙) = 10.21 (at z = 0) simulated galaxy from IllustrisTNG which is in the process of quenching. Top panels: projections at three points during the primary quenching episode, where the leftmost panel is the snapshot at the onset of quenching, the middle panel is roughly midway through quenching, and the rightmost panel is in the later stages of quenching. These projections show spatial specific star formation rates as a 2D histogram, while the green contours show the stellar mass distribution. The middle panel is 610 Myr after the leftmost panel and 650 Myr before the rightmost panel, where these panels highlight the evolution of the size of the star forming disk compared to the stellar disk. The star forming disk shows strong truncation progressing outside-in with increasing time. Comparatively, the stellar disk is mostly unchanged from panel to panel. Bottom panels: specific star formation rate radial profiles for the same time points as the top panels (red points). Median and ±1σ intervals for normal star forming galaxies with a similar stellar mass which are on the star forming main sequence are shown with a dotted black line and grey band, respectively. These panels highlight the sharp truncation that this galaxy experiences late in its quenching episode, as the radial profile displays a clear discontinuity near 2.3Re.