PHANGS: constraining star formation time-scales using the spatial correlations of star clusters and giant molecular clouds

Turner, Jordan A.; Dale, Daniel A.; Lilly, James; Boquien, Mederic; Deger, Sinan; Lee, Janice C.; Whitmore, Bradley C.; Anand, Gagandeep S.; Benincasa, Samantha M.; Bigiel, Frank; Blanc, Guillermo A.; Chevance, Melanie; Emsellem, Eric; Faesi, Christopher M.; Glover, Simon C. O.; Grasha, Kathryn; Hughes, Annie; Klessen, Ralf S.; Kreckel, Kathryn; Kruijssen, J. M. Diederik; Leroy, Adam K.; Pan, Hsi-An; Rosolowsky, Erik; Schruba, Andreas; Williams, Thomas G.
2022
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
DOI
10.1093/mnras/stac2559
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 > 10 Myr stellar populations, indicating that the hierarchical structure dissolves over time.