Understanding the role of compact star formation in galaxy evolution
Massive elliptical galaxies in the local universe appear to have their high-redshift analogs in the form of extremely compact quiescent galaxies. Therefore, it seems that compact star formation appears to play a pivotal role in the evolutionary pathways of massive galaxies across cosmic history. However, it remains to be understood what this role is in the broader picture set by the main sequence and the scaling relations in galaxy evolution. From an ALMA survey at 1.1mm, we reveal that compact star formation appears to be the norm in massive star-forming galaxies, and sizes as extended as typical star-forming stellar disks are rare. A population of galaxies with modest star formation rates, but which exhibit extremely compact star formation with starburst-like depletion timescales unveils. Compact star formation appears as a physical driver of depletion timescales, gas fractions, and dust temperatures. The new findings suggest that the star formation rate is sustained in very massive SFGs, even when their gas fractions are low and they are presumably on the way to quiescence. Gas and star formation compression seems to be a mechanism that allows to hold their star formation rate.
