Kate Rowlands

Research

My main research interests are galaxy evolution, with a focus on the multiwavelength properties of both local and distant galaxies. I use UV-radio data from large photometric and spectroscopic galaxy surveys such as UKIDSS UDS, GAMA and MaNGA to determine the star-formation histories and dust properties of large samples of galaxies.

My research interests include:

• Galaxy bimodality - starbursts, galaxy mergers, post-starburst galaxies, quenching.
• Properties, origins and evolution of dust and gas in galaxies, particularly in post-starburst galaxies, and (traditionally gas/dust-poor) early-type galaxies.
• Multiwavelength spectral energy distribution (SED) model fitting.
• Statistical interpretation of galaxy properties derived from large spectroscopic and multiwavelength photometric surveys.
• Connection between galaxy morphology and physical properties.
• Chemical evolution modelling.

Why do galaxies stop forming stars?

One key problem in astrophysics is understanding galaxy evolution and transformation, in particular how and why galaxies switch off their star formation. Whilst stellar-driven outflows are ubiquitous in star-forming galaxies at high redshift and may remove some gas, simulations suggest that additional mechanisms are required to induce a galaxy-wide shutdown in star formation. Feedback from active black holes are usually invoked to complete the transition of galaxies from star forming to quiescent, through gas heating or expulsion. However, the exact mechanisms that lead to the disruption of the gas supply and hence the shut-down of star formation, the relative importance of different quenching mechanisms, and the timescales involved are still poorly understood. My research centers on galaxy formation and evolution, in particular in galaxy transformation and quenching over cosmic time.

Post-starburst galaxies are an ideal laboratory to study quenching as they have undergone a dramatic starburst event which can rapidly exhaust and/or expel gas on a <1 billion year timescale. These galaxies are thought to be caught in the act of transformation between star-forming and quiescent. Post-starbursts are commonly assumed to be devoid of gas and dust, although recent studies Rowlands et al. (2015), have shown that low-redshift post-starbursts still harbour a significant cold interstellar medium similar to spiral galaxies. Low-redshift post-starbursts are not completely devoid of gas as was previously thought, which challenges the rapid quenching mode of forming the quiescent population (see Figure). I use my experience with multiwavelength data and statistical analysis of large datasets spanning 10 billion years of cosmic time to understand why galaxies stop forming stars.