PHANGS: constraining star formation time-scales using the spatial correlations of star clusters and giant molecular clouds
Kruijssen, J. M. Diederik; Leroy, Adam K.; Rosolowsky, Erik; Chevance, Mélanie; Glover, Simon C. O.; Hughes, Annie; Klessen, Ralf S.; Schruba, Andreas; Bigiel, Frank; Blanc, Guillermo A.; Emsellem, Eric; Whitmore, Bradley C.; Williams, Thomas G.; Kreckel, Kathryn; Grasha, Kathryn; Lee, Janice C.; Deger, Sinan; Dale, Daniel A.; Anand, Gagandeep S.; Faesi, Christopher M.; Pan, Hsi-An; Boquien, Mederic; Lilly, James; Turner, Jordan A.; Benincasa, Samantha M.
United States, Chile, Germany, France, Australia, Taiwan, Canada
Abstract
In the hierarchical view of star formation, giant molecular clouds (GMCs) undergo fragmentation to form small-scale structures made up of stars and star clusters. Here we study the connection between young star clusters and cold gas across a range of extragalactic environments by combining the high resolution (1″) PHANGS-ALMA catalogue of GMCs with the star cluster catalogues from PHANGS-HST. The star clusters are spatially matched with the GMCs across a sample of 11 nearby star-forming galaxies with a range of galactic environments (centres, bars, spiral arms, etc.). We find that after 4 - 6 Myr the star clusters are no longer associated with any gas clouds. Additionally, we measure the autocorrelation of the star clusters and GMCs as well as their cross-correlation to quantify the fractal nature of hierarchical star formation. Young (≤10 Myr) star clusters are more strongly autocorrelated on kpc and smaller spatial scales than the $\gt \, 10$ Myr stellar populations, indicating that the hierarchical structure dissolves over time.