Speaker
Description
Star formation lies at the core of the evolutionary cycle of galaxies. To better understand the mechanisms involved in star formation, we need to study the influence of the local interstellar medium (ISM) and the lifecycle of giant molecular clouds (GMCs). In this work, we study the influence of the local environment of the giant molecular clouds on the star formation process and measure the evolutionary timeline of the GMC lifecycle, star formation, and feedback on a sample of 27 nearby LIRGs. This sample covers the entire merger sequence, from isolated galaxies to late-stage mergers.
We used ALMA to map the distribution of cold molecular gas traced by the 2-1 transition of CO, along with Paα imaging from HST/NICMOS and Paβ imaging from HST/WFC3, to trace recent star formation (SF) at resolutions below 100 pc. We also analysed how SF scaling relations change depending on the study of 1) the local ISM and 2) the GMCs, across the merger sequence. These two methods reveal variations, providing distinct perspectives for studying star formation relations.
We also find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. The results of this work reveal distinct behaviours throughout the merger sequence. In isolated galaxies or galaxy pairs, the influence of interactions is minimal or negligible. In these cases, clumps do not exhibit a clear trend between star formation efficiency, the self-gravity of the gas, and velocity dispersion, even when the clumps show high gas boundedness or high velocity dispersion. However, as galaxy interactions become more pronounced—producing tidal tails, highly distorted morphologies, and a more chaotic environment—the velocity dispersion of the gas in the clumps increases. This turbulence, combined with the large gas content in these clumps, enhances the self-gravity of the gas, making them more efficient at forming stars.
